Podcasts about auditory cortex

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.08.03.551829v1?rss=1 Authors: Berto, M., Reisinger, P., Ricciardi, E., Weisz, N., Bottari, D. Abstract: The processing of stationary sounds relies on both local features and compact representations. As local information is compressed into summary statistics, abstract representations emerge. Whether the brain is endowed with distinct neural architectures overseeing such computations is unknown. In this magnetoencephalography (MEG) study, we employed a validated protocol to localize cortical correlates of local and summary representations, exposing participants to triplets of synthetic sound textures systematically varying for either local details or summary statistics. Sounds also varied for their sound duration, specifically short (40ms) or long (478ms). Results revealed clear distinct activation patterns for local features and summary statistics changes. Such activations diverged in magnitude, spatiotemporal distribution, and hemispheric lateralization. For short sounds, a change in local features, compared to summary statistics, predominantly activated the right hemisphere. Conversely, for long sounds, a change in summary statistics elicited higher activation than a change in local features in both hemispheres. Specifically, while the right auditory cortex was responding more to changes in local features or summary statistics depending on sound duration (short or long, respectively), the left frontal lobe was selectively engaged in processing a change in summary statistics at a long sound duration. These findings provide insights into the neural mechanisms underlying the computation of local and summary acoustic information and highlight the involvement of distinct cortical pathways and hemispheric lateralization in auditory processing at different temporal resolutions. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.03.547519v1?rss=1 Authors: Garcia-Rosales, F., Schaworonkow, N., Hechavarria, J. C. Abstract: Neural oscillations are associated with diverse computations in the mammalian brain. The waveform shape of oscillatory activity measured in cortex relates to local physiology, and can be informative about aberrant or dynamically changing states. However, how waveform shape differs across distant yet functionally and anatomically related cortical regions is largely unknown. In this study, we capitalize on simultaneous recordings of local field potentials (LFPs) in the auditory and frontal cortices of awake Carollia perspicillata bats to examine, on a cycle-by-cycle basis, waveform shape differences across cortical regions. We find that waveform shape differs markedly in the fronto-auditory circuit even for rhythmic activity in comparable frequency ranges (i.e. in the delta and gamma bands) during spontaneous activity. In addition, we report consistent differences between areas in the variability of waveform shape across individual cycles. A conceptual model predicts higher spike-spike and spike-LFP correlations in regions with more asymmetric shape, a phenomenon that was observed in the data: spike-spike and spike-LFP correlations were higher in frontal cortex. The model suggests a relationship between waveform shape differences and differences in spike correlations across cortical areas. Altogether, these results indicate that oscillatory activity in frontal and auditory possess distinct dynamics related to the anatomical and functional diversity of the fronto-auditory circuit. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.03.547560v1?rss=1 Authors: Morandell, K., Yin, A., Del Rio, R. T., Schneider, D. M. Abstract: Neurons in the mouse auditory cortex are strongly influenced by behavior, including both suppression and enhancement of sound-evoked responses during movement. The mouse auditory cortex comprises multiple fields with different roles in sound processing and distinct connectivity to movement-related centers of the brain. Here, we asked whether movement-related modulation might differ across auditory cortical fields, thereby contributing to the heterogeneity of movement-related modulation at the single-cell level. We used wide-field calcium imaging to identify distinct cortical fields followed by cellular-resolution two-photon calcium imaging to visualize the activity of layer 2/3 excitatory neurons within each field. We measured each neuron's responses to three sound categories (pure tones, chirps, and amplitude modulated white noise) as mice rested and ran on a non-motorized treadmill. We found that individual neurons in each cortical field typically respond to just one sound category. Some neurons are only active during rest and others during locomotion, and those that are responsive across conditions retain their sound-category tuning. The effects of locomotion on sound-evoked responses vary at the single-cell level, with both suppression and enhancement of neural responses, and the net modulatory effect of locomotion is largely conserved across cortical fields. Movement-related modulation in auditory cortex also reflects more complex behavioral patterns, including instantaneous running speed and non-locomotor movements such as grooming and postural adjustments, with similar patterns seen across all auditory cortical fields. Our findings underscore the complexity of movement-related modulation throughout the mouse auditory cortex and indicate that movement-related modulation is a widespread phenomenon. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.06.29.547009v1?rss=1 Authors: Heller, C. R., Hamersky, G. R., David, S. V. Abstract: Categorical sensory representations are critical for many behaviors, including speech perception. In the auditory system, categorical information is thought to arise hierarchically, becoming increasingly prominent in higher order cortical regions. The neural mechanisms that support this robust and flexible computation remain poorly understood. Here, we studied sound representations in primary and non-primary auditory cortex while animals engaged in a challenging sound discrimination task. Population-level decoding of simultaneously recorded single neurons revealed that task engagement caused categorical sound representations to emerge in non-primary auditory cortex. In primary auditory cortex, task engagement caused a general enhancement of sound decoding that was not specific to task-relevant categories. These findings are consistent with mixed selectivity models of neural disentanglement, in which early sensory regions build an overcomplete representation of the world and allow neurons in downstream brain regions to flexibly and selectively read out behaviorally relevant, categorical information. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.05.03.539222v1?rss=1 Authors: Bialas, O., Maess, B., Schoenwiesner, M. Abstract: Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.26.538446v1?rss=1 Authors: Gill, N. K., Francis, N. A. Abstract: Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.22.537782v1?rss=1 Authors: Akritas, M., Armstrong, A. G., Lebert, J. M., Meyer, A. F., Sahani, M., Linden, J. F. Abstract: The perceptual salience of a sound depends on the acoustic context in which it appears. Single-neuron correlates of this contextual sensitivity can be estimated from neuronal responses to complex sounds using the nonlinear-linear "context model". Context models provide estimates of both the principal (spectrotemporal) receptive field of a neuron and a "contextual gain field" describing its nonlinear sensitivity to combinations of sound input. Previous studies of contextual gain fields in auditory cortex of anesthetized mice have revealed strong neuron-specific patterns of nonlinear sensitivity to sound context. However, the stability of these patterns over time, especially in awake animals, is unknown. We recorded electrophysiological activity of neurons in the auditory cortex of awake mice over many days using chronically implanted tetrode arrays, while also obtaining continuous measures of the animal's behavioral state (locomotor activity and pupil diameter), during repeated presentations of prolonged complex sounds. Waveform matching identified neurons that were recorded over multiple days. We estimated principal receptive fields and contextual gain fields for each neuron in each recording session, and quantified the stability of these fields within and across days. We also examined the dependence of context model fits on measures of behavioral state. Contextual gain fields of auditory cortical neurons in awake mice were remarkably stable across many days of recording, and comparable in stability to principal receptive fields. Interestingly, while patterns of contextual sensitivity to sound combinations were qualitatively similar to those previously observed in anesthetized mice, there were small but significant effects of changes in locomotion or pupil size on the ability of the context model to fit temporal fluctuations in the neuronal response. We conclude that contextual sensitivity is an integral and stable feature of the neural code in the awake auditory cortex, which might be modulated by behavioral state. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.17.537188v1?rss=1 Authors: Tal, Z., Sayal, J., Fang, F., Bi, Y., Almeida, J., Fracasso, A. Abstract: Neuroplasticity is the ability of the human brain to reorganize and modify its activity throughout life. In congenital deafness, sensory-deprived cortex can be recruited to represent sensory information belonging to other modalities, a process known as cross-modal plasticity. Previous studies have indicated that the auditory cortex of congenitally deaf, but not of hearing individuals, is recruited during visual tasks. However, it is not clear to what extent, and how, these cross-modal responses in the deprived auditory cortex represent low-level visual spatial information or map the visual field. Here, we addressed this question directly in an fMRI case-study, aiming to map retinotopic features in the auditory cortex. Two congenitally deaf and one hearing participant went through a conventional retinotopy fMRI experiment with visual stimuli designed to map the visual system. Using population receptive field (pRF) modelling, we revealed retinotopic-related responses in the auditory cortex of the deaf, but not in the hearing. These responses, that were mostly lateralized to the right hemisphere, represented the contralateral visual field, and were characterized by large receptive fields, centred to near foveal areas. Interestingly, we found that these responses to visual stimuli predominantly reflected negative BOLD signals in the auditory cortex of the deaf, suggesting that visual information might be represented through cross-modal deactivation signals. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.15.536914v1?rss=1 Authors: Graham, G.-E., Chimenti, M. S., Knudtson, K., Grenard, D. N., Co, L., Sumner, M., Tchou, T., Bieszczad, K. M. Abstract: Learning can induce neurophysiological plasticity in the auditory cortex at multiple timescales. Lasting changes to auditory cortical function that persist over days, weeks, or even a lifetime, require learning-induced gene expression. Indeed, de novo transcription is the molecular determinant for whether transient experiences transform into long-term memories with a lasting impact on behavior. However, auditory cortical genes that support auditory learning, memory, and acquired sound-specific behavior are largely unknown. This report is the first to identify genome-wide changes in learning-induced gene expression within the auditory cortex thought to underlie the formation of auditory memory. Bioinformatic analyses on gene enrichment profiles from RNA sequencing identified biological pathways that include cholinergic synapses and neuroactive receptor interactions. The findings characterize key candidate effectors underlying changes in cortical function that support the formation of long-term auditory memory in the adult brain. The molecules and mechanisms identified are potential therapeutic targets to facilitate long-term and sound-specific changes to auditory function in adulthood and are now prime for future gene-targeted investigations. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.03.20.533547v1?rss=1 Authors: Dykstra, A. R., Gutschalk, A. Abstract: The conditions under which sensory stimuli require selective attention to reach awareness is a fundamental question of cognitive neuroscience. We examined this question in the context of audition utilizing M/EEG and a dual-task informational-masking paradigm. Listeners performed a demanding primary task in one ear (detecting isochronous target-tone streams embedded in random multi-tone backgrounds and counting within-stream deviants) and retrospectively reported their awareness of secondary, masker-embedded target streams in the other ear. Irrespective of attention or ear, left-AC activity strongly covaried with target-stream detection starting as early as 50 ms post-stimulus. In contrast, right-AC activity was unmodulated by detection until later, and then only weakly. Thus, under certain conditions, human ACs can functionally decouple, such that one (here, right) is automatic and stimulus-driven while the other (here, left) supports perceptual and/or task demands, including basic perceptual awareness of nonverbal sound sequences. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.21.529453v1?rss=1 Authors: Mukherjee, D., Xue, B., Chen, C.-T., Chang, M., Kao, J. P.-Y., Kanold, P. O. Abstract: Sensory perturbation in one modality results in adaptive reorganization of neural pathways within the spared modalities, a phenomenon known as crossmodal plasticity, which has been examined during or after the classic critical period. Because peripheral perturbations can alter auditory cortex (ACX) activity and functional connectivity of the ACX subplate neurons (SPNs) even before the classic critical period, called the precritical period, we investigated if retinal deprivation at birth crossmodally alters ACX activity and SPN circuits during the precritical period. We deprived newborn mice of visual inputs after birth by performing bilateral enucleation. We performed in vivo imaging in the ACX of awake pups during the first two postnatal weeks to investigate cortical activity. We found that enucleation alters spontaneous and sound-evoked activity in the ACX in an age-dependent manner. Next, we performed whole-cell patch clamp recording combined with laser scanning photostimulation in ACX slices to investigate circuit changes in SPNs. We found that enucleation alters the intracortical inhibitory circuits impinging on SPNs shifting the excitation-inhibition balance towards excitation and this shift persists after ear opening. Together, our results indicate that crossmodal functional changes exist in the developing sensory cortices at early ages before the onset of the classic critical period. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.07.527481v1?rss=1 Authors: Lu, Y., Sciaccotta, F., Kiely, L., Bellanger, B., Erisir, A., Meliza, C. D. Abstract: The acoustic environment an animal experiences early in life shapes the structure and function of its auditory system. This process of experience-dependent development is thought to be primarily orchestrated by potentiation and depression of synapses, but plasticity of intrinsic voltage dynamics may also contribute. Here we show that at the peak of the critical period for song memorization, neurons in the zebra finch caudal mesopallium, a cortical-level auditory area, can rapidly change their firing dynamics. This plasticity was only observed in birds that were reared in a complex acoustic and social environment, which also caused increased expression of the low-threshold potassium channel Kv1.1 in the plasma membrane and endoplasmic reticulum. Intrinsic plasticity depended on activity, was reversed by blocking low-threshold potassium currents, and was prevented by blocking intracellular calcium signaling. Taken together, these results suggest that Kv1.1 is rapidly mobilized to the plasma membrane by activity-dependent elevation of intracellular calcium. This produces a shift in the excitability and temporal integration of CM neurons that may be permissive for auditory learning in complex acoustic environments during a crucial period for the development of vocal perception and production. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.02.526903v1?rss=1 Authors: Kang, H., Kanold, P. O. Abstract: Listening in complex sound environments requires rapid segregation of different sound sources e.g., speakers from each other, speakers from other sounds, or different instruments in an orchestra, and also adjust auditory processing on the prevailing sound conditions. Thus, fast encoding of inputs and identifying and adapting to reoccurring sounds are necessary for efficient and agile sound perception. This adaptation process represents an early phase of developing implicit learning of sound statistics and thus represents a form of auditory memory. The auditory cortex (ACtx) is known to play a key role in this encoding process but the underlying circuits and if hierarchical processing exists are not known. To identify ACtx regions and cells involved in this process, we simultaneously imaged population of neurons in different ACtx subfields using in vivo 2-photon imaging in awake mice. We used an experimental stimulus paradigm adapted from human studies that triggers rapid and robust implicit learning to passively present complex sounds and imaged A1 Layer 4 (L4), A1 L2/3, and A2 L2/3. In this paradigm, a frozen spectro-temporally complex 'Target' sound would be randomly re-occurring within a stream of random other complex sounds. We find distinct groups of cells that are specifically responsive to complex acoustic sequences across all subregions indicating that even the initial thalamocortical input layers (A1 L4) respond to complex sounds. Cells in all imaged regions showed decreased response amplitude for reoccurring Target sounds indicating that a memory signature is present even in the thalamocortical input layers. On the population level we find increased synchronized activity across cells to the Target sound and that this synchronized activity was more consistent across cells regardless of the duration of frozen token within Target sounds in A2, compared to A1. These findings suggest that ACtx and its input layers play a role in auditory memory for complex sounds and suggest a hierarchical structure of processes for auditory memory. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.31.526457v1?rss=1 Authors: Funamizu, A., Marbach, F., Zador, A. M. Abstract: The activity of neurons in the auditory cortex is driven by both sounds and non-sensory context. To investigate the neuronal correlates of non-sensory context, we trained head-fixed mice to perform a two-alternative choice auditory task in which either reward or stimulus expectation (prior) was manipulated in blocks. Using two-photon calcium imaging to record populations of single neurons in auditory cortex, we found that both sensory and reward expectation modulated the activity of these neurons. Interestingly, the optimal decoder was stable even in the face of variable sensory representations. Neither the context nor the mouse's choice could be reliably decoded from the recorded auditory activity. Our findings suggest that in spite of modulation of auditory cortical activity by task priors, auditory cortex does not represent sufficient information about these priors to exploit them optimally and that decisions in this task require that rapidly changing sensory information be combined with more slowly varying task information extracted and represented in brain regions other than auditory cortex. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.01.526470v1?rss=1 Authors: Tobin, M., Sheth, J. N., Wood, K. C., Geffen, M. N. Abstract: Cortical neuronal populations can use a multitude of codes to represent information, each with different advantages and trade-offs. The auditory cortex represents sounds via a sparse code, which lies on the continuum between a localist representation with different cells responding to different stimuli, and a distributed representation, in which each stimulus is encoded in the relative response of each cell in the population. Being able to dynamically shift the neuronal code along this axis may help with certain tasks that require categorical or invariant representations. Cortical circuits contain multiple types of inhibitory neurons which shape how information is processed within neuronal networks. Here, we asked whether somatostatin-expressing (SST) and vasoactive intestinal peptide-expressing (VIP) inhibitory neurons may have distinct effects on population neuronal codes, differentially shifting the encoding of sounds between distributed and localist representations. We stimulated optogenetically SST or VIP neurons while simultaneously measuring the response of populations of hundreds of neurons to sounds presented at different sound pressure levels. SST activation shifted the neuronal population responses toward a more localist code, whereas VIP activation shifted them towards a more distributed code. Upon SST activation, sound representations became more discrete, relying on cell identity rather than strength. In contrast, upon VIP activation, distinct sounds activated overlapping populations at different rates. These shifts were implemented at the single-cell level by modulating the response-level curve of monotonic and nonmonotonic neurons. These results suggest a novel function for distinct inhibitory neurons in the auditory cortex in dynamically controlling cortical population codes. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.30.526321v1?rss=1 Authors: Rupert, D. D., Pagliaro, A. H., Choe, J., Shea, S. D. Abstract: Mutations in MECP2 cause the neurodevelopmental disorder Rett syndrome. MECP2 codes for methyl CpG binding protein 2 (MECP2), a transcriptional regulator that activates genetic programs for experience-dependent plasticity. Many neural and behavioral symptoms of Rett syndrome may result from dysregulated timing and threshold for plasticity. As a model of adult plasticity, we examine changes to auditory cortex inhibitory circuits in female mice when they are first exposed to pups; this plasticity facilitates behavioral responses to pups emitting distress calls. Brain-wide deletion of Mecp2 alters expression of markers associated with GABAergic parvalbumin interneurons (PVin) and impairs the emergence of pup retrieval. We hypothesized that loss of Mecp2 in PVin disproportionately contributes to the phenotype. Here we find that deletion of Mecp2 from PVin delayed the onset of maternal retrieval behavior and recapitulated the major molecular and neurophysiological features of brain-wide deletion of Mecp2. We observed that when PVin-selective mutants were exposed to pups, auditory cortical expression of PVin markers increased relative to that in wild type littermates. PVin-specific mutants also failed to show the inhibitory auditory cortex plasticity seen in wild type mice upon exposure to pups and their vocalizations. Finally, using an intersectional viral genetic strategy, we demonstrate that postdevelopmental loss of Mecp2 in PVin of the auditory cortex is sufficient to delay onset of maternal retrieval. Our results support a model in which PVin play a central role in adult cortical plasticity and may be particularly impaired by loss of Mecp2. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.06.523032v1?rss=1 Authors: Audette, N. J., Schneider, D. M. Abstract: The detection and signaling of prediction errors is central to the theory of predictive processing. Experiments that alter the sensory outcome of an animal's behavior reveal enhanced neural responses to unexpected self-generated stimuli, including many neurons that do not respond to the same stimulus heard passively. These neurons may reflect the violation of a learned sensory-motor prediction, but could also emerge due to a combination of sound and movement in a way that is independent from expectation. Here, we train mice to expect the outcome of a simple sound-generating lever behavior and record neural responses to the expected sound and sounds that deviate from expectation in multiple distinct dimensions. Our data reveal suppression of expected sound responses that is specific across multiple stimulus dimensions simultaneously and stimulus-specific prediction error neurons that depend on sensory-motor expectations. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

There is a critical need for early diagnosis of neurodevelopmental disorders. Elizabeth Torres, Ph.D., Rutgers University, shares new developments in that could aid in early detection of autism. Series: "Autism Tree Project Annual Neuroscience Conference" [Health and Medicine] [Show ID: 38391]

There is a critical need for early diagnosis of neurodevelopmental disorders. Elizabeth Torres, Ph.D., Rutgers University, shares new developments in that could aid in early detection of autism. Series: "Autism Tree Project Annual Neuroscience Conference" [Health and Medicine] [Show ID: 38391]

There is a critical need for early diagnosis of neurodevelopmental disorders. Elizabeth Torres, Ph.D., Rutgers University, shares new developments in that could aid in early detection of autism. Series: "Autism Tree Project Annual Neuroscience Conference" [Health and Medicine] [Show ID: 38391]

There is a critical need for early diagnosis of neurodevelopmental disorders. Elizabeth Torres, Ph.D., Rutgers University, shares new developments in that could aid in early detection of autism. Series: "Autism Tree Project Annual Neuroscience Conference" [Health and Medicine] [Show ID: 38391]

There is a critical need for early diagnosis of neurodevelopmental disorders. Elizabeth Torres, Ph.D., Rutgers University, shares new developments in that could aid in early detection of autism. Series: "Autism Tree Project Annual Neuroscience Conference" [Health and Medicine] [Show ID: 38391]

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.21.521407v1?rss=1 Authors: Chien, S.-C., Wang, P., Maess, B., Fishman, Y., Knoesche, T. Abstract: Evoked neural responses to sensory stimuli have been extensively investigated in humans and animal models both to enhance our understanding of brain function and to aid in clinical diagnosis of neurological and neuropsychiatric conditions. Recording and imaging techniques such as electroencephalography (EEG), magnetoencephalography (MEG), local field potentials (LFPs), and calcium imaging provide complementary information about different aspects of brain activity at different spatial and temporal scales. Modeling and simulations provide a way to integrate these different types of information to clarify underlying neural mechanisms. In this study, we aimed to shed light on the neural dynamics underlying auditory evoked responses by fitting a rate-based model to LFPs recorded via multi-contact electrodes which simultaneously sampled neural activity across cortical laminae. Recordings included neural population responses to best-frequency (BF) and non-BF tones at four representative sites in primary auditory cortex (A1) of awake monkeys. The model considered major neural populations of excitatory, parvalbumin-expressing (PV), and somatostatin-expressing (SOM) neurons across layers 2/3, 4, and 5/6. Unknown parameters, including the connection strength between the populations, were fitted to the data. Our results revealed similar population dynamics, fitted model parameters, predicted equivalent current dipoles (ECD), tuning curves, and lateral inhibition profiles across recording sites and animals, in spite of quite different extracellular current distributions. We found that PV firing rates were higher in BF than in non-BF responses, mainly due to different strengths of tonotopic thalamic input, whereas SOM firing rates were higher in non-BF than in BF responses due to lateral inhibition. In conclusion, we demonstrate the feasibility of the model-fitting approach in identifying the contributions of cell-type specific population activity to stimulus-evoked LFPs across cortical laminae, providing a foundation for further investigations into the dynamics of neural circuits underlying cortical sensory processing. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.19.521141v1?rss=1 Authors: Kumar, R., Ostojic, S., Shamma, S., Boubenec, Y. Abstract: Grouping sets of sounds into relevant categories is an important cognitive ability that facilitates the association of stimuli with appropriate goal-directed behavioral responses. In perceptual tasks, a prominent role of primary auditory cortex (A1) is to multiplex the encoding of sound sensory features and task variables. Here we investigated the involvement of A1 in initiating sound categorization. We trained ferrets to discriminate click trains of different rates in a Go/No-Go delayed categorization task and recorded neural activity during both active behavior and passive exposure to the same sounds. Purely categorical response components were extracted and analyzed separately from sensory responses to reveal their contributions to the overall population response throughout the trials. We found that population-level representation of Go/No-Go behavioral categories emerged during sound presentation and was present in both active behavioral and passive states. However, upon task engagement, categorical responses to the No-Go category became suppressed, leading to an asymmetrical representation of the Go stimuli relative to the No-Go sounds and prestimulus baseline. At stimulus offset, the population code changed abruptly but categorical representation was maintained during the delay period. Categorical responses extracted from the stimulus period correlated with the ones found in the delay epoch, suggesting an early contribution of A1 to stimulus categorization. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.14.520391v1?rss=1 Authors: Bagur, S., Bourg, J., Kempf, A., Tarpin, T., Bergaoui, K., Guo, Y., Ceballo, S., Schwenkgrub, J., Puel, J.-L., Bourien, J., Bathellier, B. Abstract: Perception generates time-invariant objects and categories from time-varying streams of information. However, individual neuron responses, even in cortex, are not time-invariant as they usually track the temporal variations of the input. Here we show that representations of time-varying sounds remain decodable even after time-averaging at the level of neuronal populations in the mouse auditory cortex. This population-scale, time-invariant property is absent in subcortical auditory regions. By implanting light-sculpted artificial representations in the cortex with optogenetics, we show that robustness to time-averaging is a necessary property for rapid association of neural representations with behavioral output. Moreover, deep neural networks which perform sound recognition and categorization tasks generate population representations that become robust to time-averaging in their deeper layers. Hence, the auditory cortex implements a generic transformation that replicates temporal information into time-independent neural population dimensions and makes it available for learning and classification. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.12.520155v1?rss=1 Authors: Liu, J., Kanold, P. O. Abstract: Predictive coding theory postulates that the brain achieves perception by actively making predictions about the incoming sensory information and correcting them if errors signals arise. These signals are likely the most relevant when the individual is actively interacting with the environment and where the sensory outcome determines the ongoing action. In addition, the cerebral cortex is thought to play a key role in generating these signals. Thus, to study the representation of error signals in the primary sensory cortex, we trained mice to perform an interactive auditory task that coupled their actions to the generated sound and perturbed this coupling to evoke putative error responses. We imaged Layer 2/3 (L2/3) and Layer 4 (L4) neurons in the mouse primary auditory cortex, and we identified not only neurons that mainly encoded action related information but also neurons encoding the mismatch between the action and the sound. These results show that a subset of A1 neurons encode the nonlinear interactions between the sound and the action. Furthermore, more L2/3 neurons encoded action related information than L4, indicating that action-sound integration emerges hierarchically in A1 circuits. Together, our results show that complex interactions between action and sound happen in A1 and that some A1 neurons responses reflect the violation of the learnt relationship between the action and sound feedback. Thus, primary sensory cortices not only encode sensory driven activity but also represent the complex interplay between sensory inputs, expectations, and errors. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.08.519561v1?rss=1 Authors: Orekhova, E. V., Fadeev, K. A., Goiaeva, D., Obukhova, T. S., Ovsiannikova, T. M., Prokofyev, A. O., Stroganova, T. A. Abstract: The spectral formant structure and periodicity pitch are the major features that determine the identity of vowels and the characteristics of the speaker. However, very little is known about how the processing of these features in the auditory cortex changes during development. To address this question, we independently manipulated the periodicity and formant structure of vowels while measuring auditory cortex responses using MEG in children aged 7-12 years and adults. We analyzed the sustained negative shift of source current associated with these vowel properties, which was present in the auditory cortex in both age groups despite differences in the transient components of the auditory response. In adults, the sustained activation associated with formant structure was lateralized to the left hemisphere early in the auditory processing stream requiring neither attention nor semantic mapping. This lateralization was not yet established in children, in whom the right hemisphere contribution to formant processing was strong and decreased during or after puberty. In contrast to the formant structure, periodicity was associated with a greater response in the right hemisphere in both children and adults. These findings suggest that left-lateralization for the automatic processing of vowel formant structure emerges relatively late in ontogenesis and pose a serious challenge to current theories of hemispheric specialization for speech processing. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.11.22.517379v1?rss=1 Authors: Ghimire, M., Cai, R., Ling, L., Brownell, K. A., Hackett, T. A., Llano, D. A., Caspary, D. M. Abstract: Tinnitus affects roughly 15-20% of the population while severely impacting 10% of those afflicted. Tinnitus pathology is multifactorial, generally initiated by damage to the auditory periphery, resulting in a cascade of maladaptive plastic changes at multiple levels of the central auditory neuraxis as well as limbic and non-auditory cortical centers. Using a well-established condition-suppression model of tinnitus, we measured tinnitus-related changes in the microcircuits of excitatory/inhibitory neurons onto layer 5 pyramidal neurons (PNs), as well as changes in the excitability of vasoactive intestinal peptide (VIP) neurons in primary auditory cortex (A1). Patch-clamp recordings from PNs in A1 slices showed tinnitus-related increases in spontaneous excitatory postsynaptic currents (sEPSCs) and decreases in spontaneous inhibitory postsynaptic currents (sIPSCs). Both measures were directly correlated to the rat's behavioral evidence of tinnitus. Tinnitus-related changes in PN excitability were independent of changes in A1 excitatory or inhibitory cell numbers. VIP neurons, part of an A1 local circuit that can disinhibit layer 5 PNs, showed significant tinnitus-related increases in excitability that directly correlated with the rat's behavioral tinnitus score. That PN and VIP changes directly correlated to tinnitus behavior, suggests an essential role in A1 tinnitus pathology. Tinnitus-related A1 changes were similar to findings in studies of neuropathic pain in somatosensory cortex suggesting a common pathology of these troublesome perceptual impairments. Improved understanding between excitatory, inhibitory and disinhibitory sensory cortical circuits can serve as a model for testing therapeutic approaches to the treatment of tinnitus and chronic pain. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.28.514155v1?rss=1 Authors: Deane, K. E., Garcia-Rosales, F., Klymentiev, R., Hechavarria, J. C., Happel, M. F. K. Abstract: The brains of black 6 mice (Mus musculus) and Seba's short-tailed bats (Carollia perspicillata) weigh roughly the same and share the mammalian neocortical laminar architecture. Bats have highly developed sonar calls and social communication and are an excellent neuroethological animal model for auditory research. Mice are olfactory and somatosensory specialists and are used frequently in auditory neuroscience, particularly for their advantage of standardization and genetic tools. Investigating their potentially different general auditory processing principles would advance our understanding of how the ecological needs of a species shape the development and function of the mammalian nervous system. We compared two existing datasets, recorded with linear multichannel electrodes down the depth of the primary auditory cortex (A1) while awake, across both species while presenting repetitive stimulus trains with different frequencies (~5 and ~40 Hz). We found that while there are similarities between cortical response profiles in bats and mice, there was a better signal to noise ratio in bats under these conditions, which allowed for a clearer following response to stimuli trains. This was most evident at higher frequency trains, where bats had stronger response amplitude suppression to consecutive stimuli. Phase coherence was far stronger in bats during stimulus response, indicating less phase variability in bats across individual trials. These results show that although both species share cortical laminar organization, there are structural differences in relative depth of layers. Better signal to noise ratio in bats could represent specialization for faster temporal processing shaped by their individual ecological niches. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.24.513560v1?rss=1 Authors: Nocon, J. C., Witter, J., Houghton, C. J., Gritton, H. J., Han, X., Sen, K. Abstract: Cortical circuits encoding sensory information consist of populations of neurons, yet how information aggregates via pooling individual cells remains poorly understood. Such pooling may be particularly important in noisy settings where single neuron encoding is degraded. One example is the cocktail party problem, with competing sounds from multiple spatial locations. How populations of neurons in auditory cortex (ACx) code competing sounds have not been previously investigated. Here, we apply a novel information theoretic approach to estimate information in populations of neurons in ACx about competing sounds from multiple spatial locations, including both summed population (SP) and labeled line (LL) codes. We find that a small subset of neurons is sufficient to nearly maximize mutual information over different spatial configurations, with the LL code outperforming the SP code, and approaching information levels attained without noise. Moreover, with a LL code, units with diverse spatial responses, including both regular and narrow-spiking units, constitute the best pool. Finally, information in the population increases with spatial separation between target and masker, in correspondence with behavioral results on spatial release from masking in human and animals. Taken together, our results reveal that a compact and diverse population of neurons in ACx provide a robust code for competing sounds from different spatial locations. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

A well-studied brain response to sound appears earlier than usual in young children with autism. The post Auditory cortex may develop early in autism appeared first on Spectrum | Autism Research News.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.09.15.508128v1?rss=1 Authors: Kumar, M., Handy, G., Kouvaros, S., Ljungqvist Brinson, L., Bizup, B., Doiron, B., Tzounopoulos, T. Abstract: Peripheral sensory organ damage leads to compensatory cortical plasticity that supports a remarkable recovery of perceptual capabilities. A major knowledge gap is the lack of precise mechanisms that explain how this plasticity is implemented and distributed over a diverse collection of excitatory and inhibitory cortical neurons. Here, we explored these mechanisms in mouse A1. After peripheral damage, we found recovered sound-evoked activity of excitatory principal neurons (PNs) and parvalbumin (PVs) interneurons (INs), reduced activity in somatostatin-INs (SOMs), and recovered activity in vasoactive intestinal peptide-INs (VIPs). Given the sequentially organized cortical network where VIPs inhibit INs, SOMs inhibit PVs and PNs, and PVs inhibit PNs, our results suggest that PVs contribute to PN stability, SOMs allow for increased PN and PV activity, and VIPs enable the PN and PV recovery by inhibiting SOMs. These results highlight a strategic, cooperative, and cell-type-specific plasticity program that restores cortical sound processing after peripheral damage. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

A well-studied brain response to sound appears earlier than usual in young children with autism.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.09.12.507667v1?rss=1 Authors: Schultheiss, H., Zulfiqar, I., Moerel, M. Abstract: Tinnitus is a clinical condition where a sound is perceived without external sound source. Homeostatic plasticity (HSP), serving to increase neural activity as compensation for the reduced input to the auditory pathway after hearing loss, has been proposed as causal mechanism underlying tinnitus. In support, animal models of tinnitus show evidence of increased neural activity after hearing loss, including increased spontaneous and sound-driven firing rate, as well as increased neural noise throughout the auditory processing pathway. Bridging these findings to human tinnitus, however, has proven to be challenging. Here we implement hearing loss-induced HSP in a Wilson-Cowan Cortical Model of the auditory cortex to predict how homeostatic principles operating at the microscale translate to the meso- to macroscale accessible through human neuroimaging. We observed HSP-induced response changes in the model that were previously proposed as neural signatures of tinnitus. As expected, HSP increased spontaneous and sound-driven responsiveness in hearing-loss affected frequency channels of the model. We furthermore observed evidence of increased neural noise and the appearance of spatiotemporal modulations in neural activity, which we discuss in light of recent human neuroimaging findings. Our computational model makes quantitative predictions that require experimental validation, and may thereby serve as the basis of future human tinnitus studies. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.09.12.507664v1?rss=1 Authors: Castellanos, A. L., De Martino, F., Ghose, G. M., Gulban, O. F., Moerel, M. Abstract: Selective attention enables the preferential processing of relevant stimulus aspects. Invasive animal studies have shown that attending a sound feature rapidly modifies neuronal tuning throughout the auditory cortex. Human neuroimaging studies have reported enhanced auditory cortical responses with selective attention. To date, it remains unclear how the results obtained with functional magnetic resonance imaging (fMRI) in humans relate to the electrophysiological findings in animal models. Here we aim to close the gap between animal and human research by combining a selective attention task similar in design to those used in animal electrophysiology with high spatial resolution ultra-high field fMRI at 7 Tesla. Specifically, human participants perform a detection task, while the probability of target occurrence varies with sound frequency. Contrary to previous fMRI studies, we show that selective attention reduces responses to the attended frequencies in those neuronal populations preferring the attended frequency. Through population receptive field (pRF) mapping, we furthermore show that these response reductions are at least partially driven by frequency-induced pRF narrowing. The difference between our results to those of previous fMRI studies supports the notion that the influence of selective attention on auditory cortex is diverse and may depend on context, task, and auditory processing stage. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

Link to original articleWelcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: On oxytocin-sensitive neurons in auditory cortex, published by Steven Byrnes on September 6, 2022 on LessWrong. (For the big picture of how I wound up on this topic, see Symbol Grounding and Human Social Instincts. But I wound up feeling like oxytocin-sensitive neurons in auditory cortex are NOT an important piece of that particular puzzle.) (I tried to minimize neuroscience jargon (as usual), but I don't really expect that non-neuroscientists would want to read this post anyway.) I just read the paper “Oxytocin enables maternal behaviour by balancing cortical inhibition” (free PDF link) by Bianca J. Marlin, Mariela Mitre, James A. D'amour, Moses V. Chao, & Robert C. Froemke at NYU (Nature, 2015). And then I spent a while feeling confused. But I think I'm no longer confused. In this post I'll explain both why I was confused, and how I got over it. Background: pup-retrieval behavior The paper concerns a behavior which is amusingly described in the following book excerpt (emphasis added): After a rat gives birth, she displays a complex repertoire of maternal behaviors. If given paper, she will shred it and use the strips to build a nest. Virgin and early pregnant rats avoid newborn pups, but a mother rat will gather her young into the nest and allow them to suckle, and if any pup wanders away she will promptly retrieve it. Indeed, she will retrieve any pup that she sees close to her nest, whether hers or not, seemingly without limit. If 20 or 30 strange pups are placed in her cage, all will be retrieved, and she will strive to ensure that all are groomed and fed. . These behaviors are expressed after normal vaginal delivery, but are disrupted by interventions that impair oxytocin release . Strikingly, maternal behavior can be induced by injecting small amounts of oxytocin into the brain, both in virgin rats when at the stage of the cycle when estrogen levels are high, and in ovariectomized rats that have been infused with estrogen. —Gareth Leng, The Heart Of the Brain: The Hypothalamus and its Hormones, p191 The Marlin et al. paper is about this pup-retrieval behavior, which the mother does in response to an isolated pup shouting a high-pitched “distress call”. Marlin et al. results (specifically concerning primary auditory cortex) Marlin et al. did a series of experiments where they found (among other things) the following: When they temporarily inactivated the left primary auditory cortex (with a muscimol infusion), it reduced pup-retrieval in experienced mothers. More specifically, it eliminated pup-retrieval in 5/16 mice, and reduced it in 8/16 mice, while the last 3/16 heroic mice continued to retrieve every last distressed pup despite the infusion. On the other hand, when they temporarily inactivated the right primary auditory cortex, it didn't do much (if anything) to pup-retrieval in experienced mothers. Specifically, it did nothing in 4/5 mice, and reduced pup retrieval in the other one, but that might have just been a random blip. They found that there were 40% more oxytocin receptors in the left primary auditory cortex than right primary auditory cortex. They also found a plausible source of oxytocin for those receptors to be detecting, namely, some fibers in primary auditory cortex coming from oxytocin-producing neurons in the hypothalamus. (There were similar numbers of such fibers on the left and right sides.) They found that if they took an experienced mother, and blocked the activity of oxytocin in her left primary auditory cortex, it did not change her pup-retrieval behavior. They found that if they took a virgin female, and locally infused oxytocin into her left primary auditory cortex shortly before pup-retrieval tests, her first pup-retrieval would happen earlier. (I think this result is probably real, but be warned that the data analysis barely rea...

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: On oxytocin-sensitive neurons in auditory cortex, published by Steven Byrnes on September 6, 2022 on LessWrong. (For the big picture of how I wound up on this topic, see Symbol Grounding and Human Social Instincts. But I wound up feeling like oxytocin-sensitive neurons in auditory cortex are NOT an important piece of that particular puzzle.) (I tried to minimize neuroscience jargon (as usual), but I don't really expect that non-neuroscientists would want to read this post anyway.) I just read the paper “Oxytocin enables maternal behaviour by balancing cortical inhibition” (free PDF link) by Bianca J. Marlin, Mariela Mitre, James A. D'amour, Moses V. Chao, & Robert C. Froemke at NYU (Nature, 2015). And then I spent a while feeling confused. But I think I'm no longer confused. In this post I'll explain both why I was confused, and how I got over it. Background: pup-retrieval behavior The paper concerns a behavior which is amusingly described in the following book excerpt (emphasis added): After a rat gives birth, she displays a complex repertoire of maternal behaviors. If given paper, she will shred it and use the strips to build a nest. Virgin and early pregnant rats avoid newborn pups, but a mother rat will gather her young into the nest and allow them to suckle, and if any pup wanders away she will promptly retrieve it. Indeed, she will retrieve any pup that she sees close to her nest, whether hers or not, seemingly without limit. If 20 or 30 strange pups are placed in her cage, all will be retrieved, and she will strive to ensure that all are groomed and fed. . These behaviors are expressed after normal vaginal delivery, but are disrupted by interventions that impair oxytocin release . Strikingly, maternal behavior can be induced by injecting small amounts of oxytocin into the brain, both in virgin rats when at the stage of the cycle when estrogen levels are high, and in ovariectomized rats that have been infused with estrogen. —Gareth Leng, The Heart Of the Brain: The Hypothalamus and its Hormones, p191 The Marlin et al. paper is about this pup-retrieval behavior, which the mother does in response to an isolated pup shouting a high-pitched “distress call”. Marlin et al. results (specifically concerning primary auditory cortex) Marlin et al. did a series of experiments where they found (among other things) the following: When they temporarily inactivated the left primary auditory cortex (with a muscimol infusion), it reduced pup-retrieval in experienced mothers. More specifically, it eliminated pup-retrieval in 5/16 mice, and reduced it in 8/16 mice, while the last 3/16 heroic mice continued to retrieve every last distressed pup despite the infusion. On the other hand, when they temporarily inactivated the right primary auditory cortex, it didn't do much (if anything) to pup-retrieval in experienced mothers. Specifically, it did nothing in 4/5 mice, and reduced pup retrieval in the other one, but that might have just been a random blip. They found that there were 40% more oxytocin receptors in the left primary auditory cortex than right primary auditory cortex. They also found a plausible source of oxytocin for those receptors to be detecting, namely, some fibers in primary auditory cortex coming from oxytocin-producing neurons in the hypothalamus. (There were similar numbers of such fibers on the left and right sides.) They found that if they took an experienced mother, and blocked the activity of oxytocin in her left primary auditory cortex, it did not change her pup-retrieval behavior. They found that if they took a virgin female, and locally infused oxytocin into her left primary auditory cortex shortly before pup-retrieval tests, her first pup-retrieval would happen earlier. (I think this result is probably real, but be warned that the data analysis barely rea...

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.08.30.505788v1?rss=1 Authors: Wadle, S. L., Schmitt, T. T., Engel, J., Kurt, S., Hirtz, J. J. Abstract: The 2{delta}3 auxiliary subunit of voltage-activated calcium channels is required for normal synaptic transmission and precise temporal processing of sounds in the auditory brainstem. In mice its loss additionally leads to an inability to distinguish amplitude-modulated (AM) tones. Furthermore, loss of function of 2{delta}3 has been associated with autism spectrum disorder (ASD) in humans. To investigate possible alterations of network activity in the high-order auditory system in 2{delta}3 KO mice, we analyzed neuronal activity patterns and topography of frequency tuning within networks of the auditory cortex (AC) using two-photon Ca2+ imaging. We found subfield-specific alterations, expressed in overall lower correlations between the network activity patterns in response to different sounds as well as lower reliability of these patterns upon repetitions of the same sound in the primary auditory cortex (A1). Higher AC subfields did not display these alterations but showed a higher amount of well-tuned neurons along with lower local heterogeneity of the neurons' frequency tuning. Our results provide new insight into AC network activity alterations in an ASD-associated mouse model. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

This episode is part two of my miniseries on the neuroscience of language production and processing and today we're touching on how the brain regions encoding those concepts change in deaf individuals. It turns out that the brain is the literal embodiment of that "its free real estate" meme and vision input takes over the auditory cortex!If you're curious to know more - come and take a listen!Also if you have the means/desire to financially support this podcast - please go to https://www.buymeacoffee.com/neuroscienceI really appreciate it!!!Citations and relevant papers are below! CDC. Genetics of Hearing Loss | CDC. Centers for Disease Control and Prevention. Published February 18, 2015. https://www.cdc.gov/ncbddd/hearingloss/genetics.html#:~:text=50%25%20to%2060%25%20of%20hearingDeafness causes before birth | Deafness in childhood. www.ndcs.org.uk. https://www.ndcs.org.uk/information-and-support/childhood-deafness/causes-of-deafness/#:~:text=Deafness%20can%20also%20be%20causedSimon M, Campbell E, Genest F, MacLean MW, Champoux F, Lepore F. The Impact of Early Deafness on Brain Plasticity: A Systematic Review of the White and Gray Matter Changes. Frontiers in Neuroscience. 2020;14. doi:10.3389/fnins.2020.00206Sharma A, Dorman MF, Spahr AJ. A Sensitive Period for the Development of the Central Auditory System in Children with Cochlear Implants: Implications for Age of Implantation. Ear and Hearing. 2002;23(6):532-539. https://journals.lww.com/ear-hearing/Abstract/2002/12000/A_Sensitive_Period_for_the_Development_of_the.4.aspxVoss P, Thomas ME, Cisneros-Franco JM, de Villers-Sidani É. Dynamic Brains and the Changing Rules of Neuroplasticity: Implications for Learning and Recovery. Frontiers in Psychology. 2017;8. doi:10.3389/fpsyg.2017.01657Purves D, Augustine GJ, Fitzpatrick D, et al. The Auditory Cortex. Nih.gov. Published 2016. https://www.ncbi.nlm.nih.gov/books/NBK10900/Bola Ł, Zimmermann M, Mostowski P, et al. Task-specific reorganization of the auditory cortex in deaf humans. Proceedings of the National Academy of Sciences. 2017;114(4):E600-E609. doi:10.1073/pnas.1609000114‌Fougnie D, Cockhren J, Marois R. A common source of attention for auditory and visual tracking. Attention, Perception, & Psychophysics. 2018;80(6):1571-1583. doi:10.3758/s13414-018-1524-9Campbell R, MacSweeney M, Waters D. Sign Language and the Brain: A Review. The Journal of Deaf Studies and Deaf Education. 2008;13(1):3-20. doi:10.1093/deafed/enm035Support the show

Welcome back! This week, I want to talk about your ears and how going to super loud concerts can impact your ability to hear. You might be thinking wait - ears aren't brains. But the way we process sound in our ears is a part of the peripheral nervous system so I say close enough!Come and listen to learn a little bit more about your auditory system, your peripheral nervous system,  hair cells, and the absolutely insane feat of biological engineering that allows for sound to go from your surroundings to your brain. Please rate, review, and subscribe and if you have any questions, comments, concerns, queries, or complaints, please email me at neuroscienceamateurhour@gmail.com or DM me at NeuroscienceAmateurHour on Instagram.Citations and relevant pictures are below:The Physics Classroom. Sound Waves as Pressure Waves. Physicsclassroom.com. Published 2019. https://www.physicsclassroom.com/class/sound/u11l1c.cfmHow the Ear Works. www.hopkinsmedicine.org. https://www.hopkinsmedicine.org/health/conditions-and-diseases/how-the-ear-works#:~:text=The%20Inner%20EarPetitpré C, Wu H, Sharma A, et al. Neuronal heterogeneity and stereotyped connectivity in the auditory afferent system. Nature Communications. 2018;9(1). doi:10.1038/s41467-018-06033-3Purves D, Augustine GJ, Fitzpatrick D, et al. The Auditory Cortex. Nih.gov. Published 2016. https://www.ncbi.nlm.nih.gov/books/NBK10900/Purves D, Augustine GJ, Fitzpatrick D, et al. The Inner Ear. Nih.gov. Published 2018. https://www.ncbi.nlm.nih.gov/books/NBK10946/Ruggero MA. Responses to sound of the basilar membrane of the mammalian cochlea. Current Opinion in Neurobiology. 1992;2(4):449-456. doi:10.1016/0959-4388(92)90179-oWagner EL, Shin JB. Mechanisms of Hair Cell Damage and Repair. Trends in Neurosciences. 2019;42(6):414-424. doi:10.1016/j.tins.2019.03.006Youm I, Li W. Cochlear hair cell regeneration: an emerging opportunity to cure noise-induced sensorineural hearing loss. Drug Discovery Today. 2018;23(8):1564-1569. doi:10.1016/j.drudis.2018.05.001Santaolalla F, Salvador C, Martínez A, Sánchez JM, del Rey AS. Inner ear hair cell regeneration: A look from the past to the future. Neural Regeneration Research. 2013;8(24):2284-2289. doi:10.3969/j.issn.1673-5374.2013.24.008Support the show

TWiN discusses the finding that rewiring retinal projections to the auditory thalamus in ferrets leads to visually responsive cells that are typical of cells in the visual cortex. Hosts: Ori Lieberman, Jason Shepherd, Timothy Cheung, and Vivianne Morrison Subscribe (free): Apple Podcasts, Google Podcasts, RSS, email Become a patron of TWiN! Links for this episode Remapping retinal projections (Nature) Sweet vs bitter taste (Nature) Timestamps by Jolene. Thanks! Music is by Ronald Jenkees Send your neuroscience questions and comments to twin@microbe.tv

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.28.359323v1?rss=1 Authors: Bergman, L., Krom, A. J., Sela, Y., Marmelshtein, A., Hayat, H., Regev, N., Nir, Y. Abstract: Despite extensive knowledge of its molecular and cellular effects, how anesthesia affects sensory processing remains poorly understood. In particular, it remains unclear whether anesthesia modestly or robustly degrades activity in primary sensory regions, and whether such changes are linked to anesthesia drug concentration vs. behavioral unresponsiveness, since these are typically confounded. To address these questions, we employed slow gradual intravenous propofol anesthesia induction (from 100 to 900-1200 mcg/kg/min) together with auditory stimulation and intermittent assessment of behavioral responsiveness while recording neuronal spiking activity in the primary auditory cortex (PAC) of eight male rats. We found that all main components of neuronal activity including spontaneous firing rates, onset response magnitudes, onset response latencies, post-onset neuronal silence duration, and late-locking to 40Hz click-trains, gradually deteriorated by 6-60% in a dose-dependent manner with increasing anesthesia levels, without showing abrupt changes around loss of righting reflex or other time-points. Thus, the dominant factor affecting PAC responses is the anesthesia drug concentration rather than any sudden, dichotomous behavioral state changes. Our findings recapitulate, within one experiment, a wide array of seemingly conflicting results in the literature that, depending on the precise definition of wakefulness (vigilant vs. drowsy) and anesthesia (just-hypnotic vs. deep surgical), report a spectrum of effects in primary regions ranging from minimal to dramatic differences. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.20.347724v1?rss=1 Authors: Carter, J. A., Bidelman, G. Abstract: Speech perception requires the grouping of acoustic information into meaningful phonetic units via the process of categorical perception (CP). Environmental masking influences speech perception and CP. However, it remains unclear at which stage of processing (encoding, decision, or both) masking affects categorization of speech signals. The purpose of this study was to determine whether linguistic interference influences the early acoustic-phonetic conversion process inherent to CP. To this end, we measured source level, event related brain potentials (ERPs) from auditory cortex (AC) and inferior frontal gyrus (IFG) as listeners rapidly categorized speech sounds along a /da/ to /ga/ continuum presented in three listening conditions: quiet, and in the presence of forward (informational masker) and time-reversed (energetic masker) 2-talker babble noise. Maskers were matched in overall SNR and spectral content and thus varied only in their degree of linguistic interference (i.e., informational masking). We hypothesized a differential effect of informational versus energetic masking on behavioral and neural categorization responses, where we predicted increased activation of frontal regions when disambiguating speech from noise, especially during lexical-informational maskers. We found (1) informational masking weakens behavioral speech phoneme identification above and beyond energetic masking; (2) low-level AC activity not only codes speech categories but is susceptible to higher-order lexical interference; (3) identifying speech amidst noise recruits a cross hemispheric circuit (ACleft [->] IFGright) whose engagement varies according to task difficulty. These findings provide corroborating evidence for top-down influences on the early acoustic-phonetic analysis of speech through a coordinated interplay between frontotemporal brain areas. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.30.321695v1?rss=1 Authors: Landemard, A., Bimbard, C., Demene, C., Shamma, S., Norman-Haignere, S. V., Boubenec, Y. Abstract: Little is known about how neural representations of natural stimuli differ across species. Speech and music for example play a unique role in human hearing, but it is unclear how auditory representations of speech and music differ between humans and other animals. Using functional Ultrasound imaging, we measured responses in ferret auditory cortex to a set of natural and spectrotemporally-matched synthetic sounds previously tested in humans, as well as natural and synthetic ferret vocalizations. Ferrets showed similar frequency and modulation tuning to that observed in humans. But while humans showed selective responses to natural speech and music in non-primary auditory cortex, ferret responses to natural and synthetic sounds were closely matched throughout primary and non-primary regions, even when tested with ferret vocalizations. This finding suggests the unique demands of speech and music have substantially altered higher-order acoustic representations in human auditory cortex, while largely preserving lower-level tuning for frequency and modulation. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.30.321687v1?rss=1 Authors: Norman-Haignere, S. V., Long, L. K., Devinsky, O., Doyle, W., Irobunda, I., Merricks, E., Feldstein, N. A., McKhann, G. M. V., Schevon, C., Flinker, A., Mesgarani, N. Abstract: To derive meaning from natural sounds, the brain must integrate information across tens to hundreds of milliseconds. But it is unknown how different regions and hemispheres of human auditory cortex collectively integrate across multiple timescales. To answer this question, we developed a novel method to estimate integration periods and applied this method to intracranial recordings. We show that human auditory cortex integrates across time hierarchically, with three-fold longer integration periods in non-primary vs. primary regions, but no difference between hemispheres. Moreover, we show that selectivity for categories, such as speech and music, is restricted to electrodes with long integration periods. These findings suggest that short-term structure in natural sounds is analyzed by general-purpose acoustic mechanisms in primary auditory cortex, and then integrated over long timescales to form category-specific representations in non-primary regions. Our study thus reveals how the human brain constructs abstract representations of sound by integrating across multiple timescales. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.24.311464v1?rss=1 Authors: Kang, H., Auksztulewicz, R., An, H., Abichacra, N., Sutter, M. L., Schnupp, J. W. H. Abstract: Learning of new auditory stimuli requires repetitive exposure to the stimulus. Fast and implicit learning of sounds presented at random times enables efficient auditory perception. However, it is unclear how such sensory encoding is processed on a neural level. We investigated neural responses that are developed from a passive, repetitive exposure to a specific sound in the auditory cortex of anesthetized rats, using electrocorticography. We presented a series of random sequences that are generated afresh each time, except for a specific reference sequence that remains constant and re-appears at random times across trials. We compared induced activity amplitudes between reference and fresh sequences. Neural responses from both primary and non-primary auditory cortical regions showed significantly decreased induced activity amplitudes for reference sequences compared to fresh sequences, especially in the beta band. This is the first study showing that neural correlates of auditory pattern learning can be evoked even in anesthetized, passive listening animal models. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.18.303651v1?rss=1 Authors: Allen, E. J., Mesik, J., Kay, K. N., Oxenham, A. J. Abstract: Frequency-to-place mapping, or tonotopy, is a fundamental organizing principle from the earliest stages of auditory processing in the cochlea to subcortical and cortical regions. Although cortical maps are referred to as tonotopic, previous studies employed sounds that covary in spectral content and higher-level perceptual features such as pitch, making it unclear whether these maps are inherited from cochlear organization and are indeed tonotopic, or instead reflect transformations based on higher-level features. We used high-resolution fMRI to measure BOLD responses in 10 participants as they listened to pure tones that varied in frequency or complex tones that independently varied in either spectral content or fundamental frequency (pitch). We show that auditory cortical gradients are in fact a mixture of maps organized both by spectral content and pitch. Consistent with hierarchical organization, primary regions were tuned predominantly to spectral content, whereas higher-level pitch tuning was observed bilaterally in surrounding non-primary regions. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.07.284455v1?rss=1 Authors: Ganesan, K., Plass, J., Beltz, A. M., Liu, Z., Grabowecky, M., Suzuki, S., Stacey, W. C., Wasade, V. S., Towle, V. L., Tao, J. X., Wu, S., Issa, N. P., Brang, D. Abstract: Speech perception is a central component of social communication. While speech perception is primarily driven by sounds, accurate perception in everyday settings is also supported by meaningful information extracted from visual cues (e.g., speech content, timing, and speaker identity). Previous research has shown that visual speech modulates activity in cortical areas subserving auditory speech perception, including the superior temporal gyrus (STG), likely through feedback connections from the multisensory posterior superior temporal sulcus (pSTS). However, it is unknown whether visual modulation of auditory processing in the STG is a unitary phenomenon or, rather, consists of multiple temporally, spatially, or functionally discrete processes. To explore these questions, we examined neural responses to audiovisual speech in electrodes implanted intracranially in the temporal cortex of 21 patients undergoing clinical monitoring for epilepsy. We found that visual speech modulates auditory processes in the STG in multiple ways, eliciting temporally and spatially distinct patterns of activity that differ across theta, beta, and high-gamma frequency bands. Before speech onset, visual information increased high-gamma power in the posterior STG and suppressed beta power in mid-STG regions, suggesting crossmodal prediction of speech signals in these areas. After sound onset, visual speech decreased theta power in the middle and posterior STG, potentially reflecting a decrease in sustained feedforward auditory activity. These results are consistent with models that posit multiple distinct mechanisms supporting audiovisual speech perception. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.31.276584v1?rss=1 Authors: Heller, C. R., Schwartz, Z. P., Saderi, D., David, S. V. Abstract: In addition to encoding sound stimulus features, activity in primary auditory cortex (A1) is modulated by non-sensory behavioral state variables, including arousal. Here, we investigated how arousal, measured by pupil size, influences stimulus discriminability in A1. To do this, we recorded from populations of A1 neurons in awake animals while presenting a diverse set of natural sound stimuli. In contrast to previous work, the large stimulus set allowed us to investigate effects of arousal across a wide range of sensory response space. Arousal consistently increased evoked response magnitude and reduced pairwise noise correlations. On average, these changes improved the accuracy of the neural code. However, effects varied across stimuli; neural coding was most improved for areas of the sensory space where noise correlations interfered with the sensory discrimination axis. We also found that first-order modulation of evoked responses and second-order modulation of correlated variability acted on distinct neural populations and timescales, suggesting that arousal interacts with multiple circuits underlying activity in A1. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.25.264200v1?rss=1 Authors: Nogueira, I., Winne, J., Lima, T. Z., Malfatti, T. E., Leao, R. N., Leao, K. E. Abstract: Loud noise-exposure generates tinnitus in both humans and animals. Macroscopic studies show that noise exposure affects the auditory cortex; however, cellular mechanisms of tinnitus generation are unclear. Here we compare membrane properties of layer 5 (L5) pyramidal cells (PCs) of the primary auditory cortex (A1) from control and noise-exposed mice. PCs were previously classified in type A or type B based on connectivity and firing properties. Our analysis based on a logistic regression model predicted that afterhyperpolatization and afterdepolarization following the injection of inward and outward current are enough to predict cell type and these features are preserved after noise trauma. One week after a noise-exposure (4-18kHz, 90dB, 1.5 hr, followed by 1.5hr silence) no passive membrane properties of type A or B PCs were altered but principal component analysis showed greater separation between control/noise-exposure recordings for type A neurons. When comparing individual firing properties, noise exposure differentially affected type A and B PC firing frequency in response to depolarizing current steps. Specifically, type A PCs decreased both initial and steady state firing frequency and type B PCs significantly increased steady state firing frequency following noise exposure. These results show that loud noise can cause distinct effects on type A and B L5 auditory cortex PCs one week following noise exposure. As the type A PC electrophysiological profile is correlated to corticofugal L5 neurons, and type B PCs correlate to contralateral projecting PCs these alterations could partially explain the reorganization of the auditory cortex observed in tinnitus patients. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.05.237727v1?rss=1 Authors: Bidelman, G., Brown, J. A., Bashivan, P. Abstract: Working memory (WM) is a fundamental construct of human cognition that predicts important faculties such as language abilities and scholastic achievement. The neural basis of auditory WM is thought to reflect a distributed brain network consisting of canonical memory and central executive brain regions including frontal lobe, prefrontal areas, and hippocampus. Yet, the role of auditory (sensory) cortex in supporting active memory representations remains controversial. Here, we recorded neuroelectric activity via EEG as listeners actively performed an auditory version of the Sternberg memory task. Memory load was taxed by parametrically manipulating the number of auditory tokens (letter sounds) held in memory. Source analysis of scalp potentials showed that sustained neural activity maintained in auditory cortex (AC) prior to memory retrieval closely scaled with behavioral performance. Brain-behavior correlations revealed lateralized modulations in left (but not right) AC predicted individual differences in auditory WM capacity. Our findings confirm a prominent role of auditory cortex, traditionally viewed as a sensory-perceptual processor, in actively maintaining memory traces and dictating individual differences in behavioral WM limits. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.28.224048v1?rss=1 Authors: Lee, C. M., Sadowski, R. N., Schantz, S. L., Llano, D. A. Abstract: Polychlorinated biphenyls (PCBs) are enduring environmental toxicants and exposure is associated with neurodevelopmental deficits. The auditory system appears particularly sensitive, as previous work has shown that developmental PCB exposure causes both hearing loss and gross disruptions in the organization of the rat auditory cortex. However, the mechanisms underlying PCB-induced changes are not known, nor is it known if the central effects of PCBs are a consequence of peripheral hearing loss. Here, we study changes in both peripheral and central auditory function in rats with developmental PCB exposure using a combination of optical and electrophysiological approaches. Female rats were exposed to an environmental PCB mixture in utero and until weaning. At adulthood, auditory brainstem responses were measured, and synaptic currents were recorded in slices from auditory cortex layer 2/3 neurons. Spontaneous and miniature inhibitory postsynaptic currents (IPSCs) were more frequent in PCB-exposed rats compared to controls and the normal relationship between IPSC parameters and peripheral hearing was eliminated in PCB-exposed rats. No changes in spontaneous EPSCs were found. Conversely, when synaptic currents were evoked by laser photostimulation of caged-glutamate, PCB exposure did not affect evoked inhibitory transmission, but increased the total excitatory charge, the number and distance of sites that evoke a significant response. Together, these findings indicate that early developmental exposure to PCBs causes long-lasting changes in both inhibitory and excitatory neurotransmission in the auditory cortex that are independent of peripheral hearing changes, suggesting the effects are due to the direct impact of PCBs on the developing auditory cortex. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.28.225680v1?rss=1 Authors: Fehrman, C., Robbins, T. D., Meliza, C. D. Abstract: Neurons exhibit diverse intrinsic dynamics, which govern how they integrate synaptic inputs to produce spikes. Intrinsic dynamics are often plastic during development and learning, but the effects of these changes on stimulus encoding properties are not well known. To examine this relationship, we simulated auditory responses to zebra finch song using a linear-dynamical cascade model, which combines a linear spectrotemporal receptive field with a dynamical, conductance-based neuron model, then used generalized linear models to estimate encoding properties from the resulting spike trains. We focused on the effects of a low-threshold potassium current (KLT) that is present in a subset of cells in the zebra finch caudal mesopallium and is affected by early auditory experience. We found that KLT affects both spike adaptation and the temporal filtering properties of the receptive field. Interestingly, the direction of the effects depended on the temporal modulation tuning of the linear (input) stage of the cascade model, indicating a strongly nonlinear relationship. These results suggest that small changes in intrinsic dynamics in tandem with differences in synaptic connectivity can have dramatic effects on the tuning of auditory neurons. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.23.167833v1?rss=1 Authors: Meng, X., Borges, B. C., Long, P., Kanold, P. O., Corfas, G. Abstract: Myelination of central nervous system axons increases the conduction speed of neural impulses and contributes to the function and maintenance of neural circuits. Accordingly, loss of myelin leads to axonal loss and to severe brain dysfunction. In contrast, much less is known about the functional consequences of mild hypomyelination on central network connectivity. To address this gap in knowledge, we studied mice that have mild hypomyelination due to loss of oligodendrocyte ErbB receptor signaling. We focused on the primary auditory cortex (A1) due to the crucial role that temporal precision plays in the processing of auditory information. We find that loss of oligodendrocyte ErbB receptor signaling causes reduction in myelin in A1. We mapped and quantified the intracortical inputs to L2/3 neurons using laser-scanning photostimulation combined with patch clamp recordings. We found that hypomyelination reduces inhibitory connections to L2/3 neurons without affecting excitatory inputs, thus altering excitatory/inhibitory balance. Remarkably, these effects are not associated with changes in the expression of GABAergic and glutamatergic synaptic components, but with a reduction of parvalbumin (PV) neuron density and PV mRNA levels. These results demonstrate that mild hypomyelination can impact cortical neuronal networks and cause a network shift towards excitation. Copy rights belong to original authors. Visit the link for more info

In this episode of Where Is My Mind, Niall Breslin explores our culture of distraction, and how the perpetual pings, dings and notifications we do battle with every day in the war for our attention can stop us from deepening our attention and make us feel overwhelmed.David O'Brien's brain surgery playlist, The Auditory Cortex is here: https://spoti.fi/2M2VyjHProduced by Niall Breslin and Ciara O'Connor Walsh Learn more about your ad choices. Visit podcastchoices.com/adchoicesSee omnystudio.com/listener for privacy information.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.16.155432v1?rss=1 Authors: Saderi, D., Schwartz, Z. P., Heller, C. R., Pennington, J. R., David, S. V. Abstract: The brain's representation of sound is influenced by multiple aspects of internal behavioral state. Following engagement in an auditory discrimination task, both generalized arousal and task-specific control signals can influence auditory processing. To isolate effects of these state variables on auditory processing, we recorded single-unit activity from primary auditory cortex (A1) and the inferior colliculus (IC) of ferrets as they engaged in a go/no-go tone detection task while simultaneously monitoring arousal via pupillometry. We used a generalized linear model to isolate the contributions of task engagement and arousal on spontaneous and evoked neural activity. Fluctuations in pupil-indexed arousal were correlated with task engagement, but these two variables could be dissociated in most experiments. In both A1 and IC, individual units could be modulated by task and/or arousal, but the two state variables affected independent neural populations. Arousal effects were more prominent in IC, while arousal and engagement effects occurred with about equal frequency in A1. These results indicate that some changes in neural activity attributed to task engagement in previous studies should in fact be attributed to global fluctuations in arousal. Arousal effects also explain some persistent changes in neural activity observed in passive conditions post-behavior. Together, these results indicate a hierarchy in the auditory system, where generalized arousal enhances activity in the midbrain and cortex, while task-specific changes in neural coding become more prominent in cortex. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.08.121624v1?rss=1 Authors: Hamilton, L. S., Oganian, Y., Chang, E. F. Abstract: Speech perception involves the extraction of acoustic and phonological features from the speech signal. How those features map out across the human auditory cortex is unknown. Complementary to noninvasive imaging, the high spatial and temporal resolution of intracranial recordings has greatly contributed to recent advances in our understanding. However, these approaches are typically limited by piecemeal sampling of the expansive human temporal lobe auditory cortex. Here, we present a functional characterization of local cortical encoding throughout all major regions of the primary and non-primary human auditory cortex. We overcame previous limitations by using rare direct recordings from the surface of the temporal plane after surgical microdissection of the deep Sylvian fissure between the frontal and temporal lobes. We recorded neural responses using simultaneous high-density direct recordings over the left temporal plane and the lateral superior temporal gyrus, while participants listened to natural speech sentences and pure tone stimuli. We found an anatomical separation of simple spectral feature tuning, including tuning for pure tones and absolute pitch, on the superior surface of the temporal plane, and complex tuning for phonological features, relative pitch and speech amplitude modulations on lateral STG. Broadband onset responses are unique to posterior STG and not found elsewhere in auditory cortices. This onset region is functionally distinct from the rest of STG, with latencies similar to primary auditory areas. These findings reveal a new, detailed functional organization of response selectivity to acoustic and phonological features in speech throughout the human auditory cortex. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.04.129205v1?rss=1 Authors: Steinmetzger, K., Shen, Z., Riedel, H., Rupp, A. Abstract: To validate the use of functional near-infrared spectroscopy (fNIRS) in auditory perception experiments, combined fNIRS and electroencephalography (EEG) data were obtained from normal-hearing subjects passively listening to speech-like stimuli without linguistic content. The fNIRS oxy-haemoglobin (HbO) results were found to be inconsistent with the deoxy-haemoglobin (HbR) and EEG data, as they were dominated by pronounced cerebral blood stealing in anterior-to-posterior direction. This large-scale bilateral gradient in the HbO data masked the right-lateralised neural activity in the auditory cortex that was clearly evident in the HbR data and EEG source reconstructions. When the subjects were subsequently split into subgroups with more positive or more negative HbO responses in the right auditory cortex, the former group surprisingly showed smaller event-related potentials, less activity in frontal cortex, and increased EEG alpha power, all indicating reduced attention and vigilance. These findings thus suggest that positive HbO responses in the auditory cortex may not necessarily be a favourable result when investigating auditory perception using fNIRS. More generally, the results show that the interpretation of fNIRS HbO signals can be misleading and demonstrate the benefits of combined fNIRS-EEG analyses in resolving this issue. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.28.121459v1?rss=1 Authors: Clayton, K. K., Williamson, R. S., Watanabe, Y., Hancock, K. E., Tasaka, G.-i., Mizrahi, A., Hackett, T., Polley, D. B. Abstract: During active sensing, neural responses to sensory inputs directly generated by our own movements are suppressed. In the auditory cortex (ACtx), self-initiated movements elicit corollary discharge from secondary motor cortex (M2) that suppresses pyramidal neuron (PyrN) spiking via recruitment of local inhibitory neurons. Here, we observed that ACtx layer (L)6 PyrNs were also activated hundreds of milliseconds prior to movement onset, at approximately the same time as fast spiking inhibitory neurons. Most L6 PyrNs were corticothalamic (CT) cells, which all expressed FoxP2, a protein marker enriched in brain areas that integrate sensory inputs to control vocal motor behaviors. L6 CTs were strongly activated prior to orofacial movements, but not locomotion, and received ten times more direct inputs from the basal ganglia than M2. These findings identify new pathways and local circuits for motor modulation of sound processing and suggest a new role for CT neurons in active sensing. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.05.079012v1?rss=1 Authors: Slater, B. J., Isaacson, J. S. Abstract: Sensory cortical areas receive glutamatergic callosal projections that link information processing between brain hemispheres. However, the role of interhemispheric projections in sensory processing is unclear. Here we use single unit recordings and optogenetic manipulations in awake mice to probe how callosal inputs modulate spontaneous and tone-evoked activity in primary auditory cortex (A1). Although activation of callosal fibers increased firing of some pyramidal cells, the majority of responsive cells were suppressed. In contrast, callosal stimulation consistently increased fast spiking (FS) cell activity and brain slice recordings indicated that parvalbumin (PV)-expressing cells receive stronger callosal input than pyramidal cells or other interneuron subtypes. In vivo silencing of the contralateral cortex revealed that callosal inputs linearly modulate tone-evoked pyramidal cell activity via both multiplicative and subtractive operations. These results suggest that callosal input regulates both the salience and tuning sharpness of tone responses in A1 via PV cell-mediated feedforward inhibition. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.30.069906v1?rss=1 Authors: van Bijnen, S., Parkkonen, L., Parviainen, T. Abstract: Sensory processing during development is important for the emerging cognitive skills underlying goal-directed behavior. Yet, it is not known how auditory processing in children is related to their cognitive functions. Here, we utilized combined magneto- and electroencephalographic (M/EEG) measurements to show that child-unique auditory cortical activity at ~250 ms after auditory stimulation predicts the performance in inhibition tasks. While unaffected by task demands, the amplitude of the left-hemisphere response was significantly correlated with the variability of behavioral response time. Since this response is not present in adults, our results suggest divergent brain mechanisms in adults and children for consistent performance in auditory-based cognitive tasks. This difference can be explained as a shift in cognitive control functionality from sensorimotor associations in the auditory cortex of children to top-down regulated control processes involving (pre)frontal and cingulate areas in adults. Copy rights belong to original authors. Visit the link for more info

Learn about a research-backed way to achieve better self control by asking for help from others; how Ambystoma salamanders “steal” DNA from other species via kleptogenesis; and how your brain can process visual information as sound. For better self control, ask for support from others by Kelsey Donk Juan Pablo Bermúdez. (2020, January 15). Self-Reliance Isn’t a Superpower, It’s a Vice. Medium; Elemental. https://elemental.medium.com/self-reliance-isnt-a-superpower-it-s-a-vice-976508e18774  Duckworth, A. L., Milkman, K. L., & Laibson, D. (2018). Beyond Willpower: Strategies for Reducing Failures of Self-Control. Psychological Science in the Public Interest, 19(3), 102–129. https://doi.org/10.1177/1529100618821893  Kleptogenesis is evolution's weirdest breeding technique by Cameron Duke Feltman, R. (2017, June 14). How a female-only line of salamanders “steals” genes from unsuspecting males. Popular Science; Popular Science. https://www.popsci.com/female-salamander-kleptogenesis/  Unisexual salamanders (genus Ambystoma) present a new reproductive mode for eukaryotes - Genome. (2020). Genome. https://www.nrcresearchpress.com/doi/abs/10.1139/G06-152#.Xk2rBpNKhhE  Bi, K., & Bogart, J. P. (2006). Identification of intergenomic recombinations in unisexual salamanders of the genus Ambystoma by genomic in situ hybridization (GISH). Cytogenetic and Genome Research, 112(3–4), 307–312. https://doi.org/10.1159/000089885  Parthenogenesis - an overview | ScienceDirect Topics. (2019). Sciencedirect.Com. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/parthenogenesis  Ambystoma barbouri (Streamside Salamander). (2017). Animal Diversity Web. https://animaldiversity.org/accounts/Ambystoma_barbouri/  Lip reading without sound lights up your auditory cortex, and scientists now know why by Grant Currin Hearing through lip-reading. (2020). EurekAlert! https://www.eurekalert.org/pub_releases/2020-01/sfn-htl010220.php  What is Magnetoencephalography (MEG)? | Institute for Learning and Brain Sciences (I-LABS). (2012). Washington.edu. http://ilabs.washington.edu/what-magnetoencephalography-meg  Bourguignon, M., Baart, M., Kapnoula, E. C., & Molinaro, N. (2019). Lip-Reading Enables the Brain to Synthesize Auditory Features of Unknown Silent Speech. The Journal of Neuroscience, 40(5), 1053–1065. https://doi.org/10.1523/jneurosci.1101-19.2019  Subscribe to Curiosity Daily to learn something new every day with Cody Gough and Ashley Hamer. You can also listen to our podcast as part of your Alexa Flash Briefing; Amazon smart speakers users, click/tap “enable” here: https://curiosity.im/podcast-flash-briefing

In this episode of Where Is My Mind, Niall Breslin explores our culture of distraction, and how the perpetual pings, dings and notifications we do battle with every day in the war for our attention can stop us from deepening our attention and make us feel overwhelmed.David O'Brien's brain surgery playlist, The Auditory Cortex is here: https://spoti.fi/2M2VyjHProduced by Niall Breslin and Ciara O’Connor Walsh See acast.com/privacy for privacy and opt-out information.

Learn about why researchers have broken down the smell of old books; new research that shows why your brain has a kind of Spider-sense; and the Panspermia theory that human life originally came from outer space. In this podcast, Cody Gough and Ashley Hamer discuss the following stories from Curiosity.com to help you get smarter and learn something new in just a few minutes: Researchers Have Broken Down the Smell of Old Books — https://curiosity.im/2V6WlkL Magic Or Medicine: Medieval Mysteries [Curiosity Podcast Episode] — https://curiosity.im/2trTo2y Seeing and Reacting to a Threat Doesn't Happen in the Order You Think — https://curiosity.im/2V7XjO2 The Panspermia Theory Says Humans Are From Outer Space — https://curiosity.im/2V98Cp9 If you love our show and you're interested in hearing full-length interviews, then please consider supporting us on Patreon. You'll get exclusive episodes and access to our archives as soon as you become a Patron! https://www.patreon.com/curiositydotcom Download the FREE 5-star Curiosity app for Android and iOS at https://curiosity.im/podcast-app. And Amazon smart speaker users: you can listen to our podcast as part of your Amazon Alexa Flash Briefing — just click “enable” here: https://curiosity.im/podcast-flash-briefing.

Learn why watching TV together is good for your relationship; why you don’t hear your own footsteps; and how to schedule your day to be as productive as overachievers like Elon Musk and Bill Gates. In this podcast, Cody Gough and Ashley Hamer discuss the following stories from Curiosity.com to help you get smarter and learn something new in just a few minutes: Watching TV Together Is Good for Your Relationship — https://curiosity.im/2Dfgb8I Why Don't You Hear Your Own Footsteps? Neuroscience Has an Answer — https://curiosity.im/2RVdrjZ Elon Musk and Bill Gates Schedule Their Days in 5-Minute Chunks — https://curiosity.im/2DclR3v Please tell us about yourself and help us improve the show by taking our listener survey! https://www.surveymonkey.com/r/curiosity-listener-survey If you love our show and you're interested in hearing full-length interviews, then please consider supporting us on Patreon. You'll get exclusive episodes and access to our archives as soon as you become a Patron! Learn about these topics and more on Curiosity.com, and download our 5-star app for Android and iOS. Then, join the conversation on Facebook, Twitter, and Instagram. Plus: Amazon smart speaker users, enable our Alexa Flash Briefing to learn something new in just a few minutes every day!

This video introduces the auditory cortex, including its physiology and role in sound localization. Also discussed is the pitch area.

This video discusses echolocation by bats and the cortical processing of language.

Researchers develop a model for how we find certain sounds, like nails on a chalkboard, unbearable. Christie Nicholson reports

Recent research has confirmed that in blind subjects who use echolocation to navigate, it is the visual part of the brain that processes the auditory echoes. Christie Nicholson reports

The auditory cortex is the acoustically responsive part of the neocortex and represents the highest level of processing of the ascending auditory pathway. The experiments described in this thesis were designed to study the auditory cortex of the microchiropteran bat Phyllostomus discolor with both, simple and complex acoustic stimuli. During the experiments, different methods were used (e.g. psychophysics and neuroanatomy), but the main focus was laid on the electrophysiological examination of the auditory cortex. The first chapter covers a study that investigated the hearing range of P. discolor by measuring neural and behavioral audiograms in this species. This study shows that acoustic stimuli at frequencies between 4 and 100 kHz could elicit either a neuronal or behavioral response in P. discolor. Lowest thresholds were found in the high frequency range above 35 kHz indicating the high sensitivity of the auditory system of P. discolor to ultrasonic sounds as for example contained in echolocation calls. However, electrophysiologically and psychophysically determined hearing thresholds lay in the range of thresholds known for other bat species. The second chapter describes a study that determined the location, extend, and subdivision of the auditory cortex of P. discolor. The area that contained acoustically responsive neurons was laterally positioned at the caudal part of the neocortex. Within this area four major cortical subfields could be distinguished based on neuroanatomical and neurophysiological criteria. The two ventral fields were tonotopically organized and were assumed to belong to the “core” region of the auditory cortex. The posterior ventral field showed properties similar to that found in the primary auditory cortex of other mammals, whereas, the anterior ventral field seems to resemble the anterior auditory field of the mammalian auditory cortex. The two dorsally located subfields did not show a clear tonotopy, but contained neurons, which were mainly responsive to high frequencies above 45 kHz. As the dominant harmonics of the echolocation call of P. discolor cover this high frequency range, the anterior and posterior dorsal fields seem to be strongly involved in processing of information obtained from echolocation. The third and fourth chapter describes experiments that investigated the cortical processing of sound parameters relevant for echolocation: echo roughness and acoustic motion. Echo roughness as a measure for the temporal envelope fluctuation of a signal is especially important for the discrimination of complex targets like trees and bushes. Broad leaved trees produce echoes with a higher degree of roughness compared to small leafed trees, e.g. conifers. The neurophysiological experiment described in chapter three revealed a population of cortical neurons in the anterior part of the auditory cortex, which encoded echo roughness in their response rate. The response of these neurons could be correlated to the behaviorally measured discrimination performance of P. discolor. In the experiment described in chapter four, pairs of pure tones were used to simulate either echoes from an object moving in azimuth or echoes from a stationary object encountered by a bat during approach. In the posterior dorsal field of the auditory cortex of P. discolor a population of motion sensitive neurons was found, which showed strong response facilitation to dynamic stimuli in contrast to static stimulation. In a subset of motion sensitive neurons the dynamic azimuthal response range was focused to small areas in the frontal field at short temporal intervals between the two components of the dynamic stimuli. The response of these neurons might be important for the tracking of targets during an approach by the bat. The results presented in this thesis reveal that the auditory cortex of P. discolor is functionally parcellated into at least four different fields. This parcellation seems to reflect the segregated processing of behaviorally and ecologically important echo parameters within specialized areas of the auditory cortex.

Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p

Background: The mammalian auditory cortex can be subdivided into various fields characterized by neurophysiological and neuroarchitectural properties and by connections with different nuclei of the thalamus. Besides the primary auditory cortex, echolocating bats have cortical fields for the processing of temporal and spectral features of the echolocation pulses. This paper reports on location, neuroarchitecture and basic functional organization of the auditory cortex of the microchiropteran bat Phyllostomus discolor (family: Phyllostomidae). Results: The auditory cortical area of P. discolor is located at parieto-temporal portions of the neocortex. It covers a rostro-caudal range of about 4800 mu m and a medio-lateral distance of about 7000 mu m on the flattened cortical surface. The auditory cortices of ten adult P. discolor were electrophysiologically mapped in detail. Responses of 849 units (single neurons and neuronal clusters up to three neurons) to pure tone stimulation were recorded extracellularly. Cortical units were characterized and classified depending on their response properties such as best frequency, auditory threshold, first spike latency, response duration, width and shape of the frequency response area and binaural interactions. Based on neurophysiological and neuroanatomical criteria, the auditory cortex of P. discolor could be subdivided into anterior and posterior ventral fields and anterior and posterior dorsal fields. The representation of response properties within the different auditory cortical fields was analyzed in detail. The two ventral fields were distinguished by their tonotopic organization with opposing frequency gradients. The dorsal cortical fields were not tonotopically organized but contained neurons that were responsive to high frequencies only. Conclusion: The auditory cortex of P. discolor resembles the auditory cortex of other phyllostomid bats in size and basic functional organization. The tonotopically organized posterior ventral field might represent the primary auditory cortex and the tonotopically organized anterior ventral field seems to be similar to the anterior auditory field of other mammals. As most energy of the echolocation pulse of P. discolor is contained in the high-frequency range, the non-tonotopically organized high-frequency dorsal region seems to be particularly important for echolocation.

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A. A fundamental property of hearing is the decomposition of complex sounds into perceptually distinct frequency components. Each receptor cell in the cochlea and most centrally located neurons respond only to a limited range of frequencies. The individual frequency channels are spatially organized on the cortical surface. This consistent topographical pattern provides a framework for the investigation of other functional organization principles, e.g., the functional properties of neurons in the six cortical layers and the responsiveness of neurons to complex sounds. The frequency specific features of inhibition should play an important role in shaping a neuron’s response to complex behaviorally relevant stimuli. Physiological and immunocytochemical evidence indicates a layer-dependent organization of inhibitory circuits in the neocortex. To investigate the contribution of GABAergic inhibition to frequency tuning in the different cortical layers, single and multi units were recorded in near-radial penetrations before and during iontophoretic application of the GABAA-receptor antagonist bicuculline in the auditory cortex of the lightly anaesthetized gerbil (Meriones unguiculatus). Bicuculline generally increased the spontaneous neuronal activity and enhanced and prolonged onset responses to sound. Application of bicuculline often resulted in a shift of the most sensitive frequency of the neurons’ receptive fields and a decrease of threshold (5.5 dB). A broadening of the frequency tuning evident by lower Q40dB values was observed in 63% of the units. In units with several peaks in their tuning curve or clearly separated response areas, bicuculline application removed inhibitory gaps in the receptive fields and created single-peaked tuning curves. The influence of bicuculline on the receptive field size was not significantly layer-specific but tended to be most pronounced in layers V and VI. In layer VI, "silent" neurons were frequently found that responded to sound only when GABAergic inhibition was antagonized. From the analysis of postembedding GABA immunocytochemistry, the proportion of GABAergic neurons was found to be maximal in layers I and V, and the number of GABAergic perisomatic puncta (axon terminals) on cell somata peaked in layer V. The influence of bicuculline was compared with the effects of two-tone suppression. It was found that in some units, the effects of suppression could be partially mediated by intracortical GABAergic inhibition. In some units in layers IV, V, and VI, additionally to the initial excitatory activity in response to stimulus onset, a second, long-lasting excitatory response occurred several hundred milliseconds after the stimulus. This late response was not dependent on stimulus duration and could be enhanced or elicited by GABAA blockade. The fact that several, rhythmically occurring late responses were elicited by the application of bicuculline suggests that recurrent excitatory networks can become entrained by small modifications of inhibition. B. In the natural environment, acoustic signals like animals’ communication sound or human speech is often masked by background noise. Amplitude fluctuations are often superimposed upon environmental sounds on their path of transmission which can lead to a distinct temporal structure of the sound. Furthermore, many natural background sounds are often temporally structured. Vertebrates have evolved mechanisms to exploit amplitude modulations in background noise to improve signal detection. Psychophysical and behavioral experiments have shown that amplitude-modulated background noise (comodulated noise) is less effective as a masker than unmodulated noise bands of the same bandwidth, a phenomenon called comodulation masking release (CMR). This phenomenon has been extensively studied in human psychoacoustics. However, the underlying neural mechanisms are still debated. Animal models in which a direct comparison of the neuronal response and the behaviorally measured performance is possible could increase our understanding of the underlying mechanisms. CMR could be demonstrated behaviorally and neurophysiologically in a songbird, however, models for mammals are still lacking. In behavioral experiments, Kittel et al. (2000) demonstrated CMR in the gerbil. In the present study, using acoustic stimuli that were identical with those of a behavioral experiment, a neural correlate of CMR was described in the auditory cortex of the gerbil and compared with the behavioral data. In this study of neural mechanisms of masking release in the primary auditory cortex of the anaesthetized gerbil, I determined neural detection thresholds for 200-ms test tones presented in a background of band-pass amplitude modulated (50 Hz) noise maskers of different bandwidth (between 50 and 3200 Hz). Neural release from masking caused by comodulated band-pass noise was evident at the level of the gerbil’s primary auditory cortex. On average, the largest masking release (median 6.9 dB) was found for a masker bandwidth of 3200 Hz. This is less than the median masking release of 15.7 dB observed in the behavioral study in the gerbil. For most masker bandwidths, however, a small fraction of the neurons exhibited a masking release that was close to or even larger than the behavioral masking release. The observation that the release from masking increased as a function of the masker bandwidth indicates that spectral components remote from the signal frequency enhance the signal detection. However, there was no correlation between the neurons’ filter bandwidths and the amount of masking release. Thus, neuronal masking release in the gerbil primary auditory cortex could be attributed to both signalmasker interactions across different frequency channels and also to mechanisms that act within a single frequency channel. The gerbil appears to be a suitable animal model for additional studies comparing behavioral and physiological performance in the same species. These studies could increase our understanding of the perceptual mechanisms that are useful for the analysis of auditory scenes.

This study investigated the representation of acoustic motion in different fields of auditory cortex of the rufous horseshoe bat, Rhinolophus rouxi. Motion in horizontal direction (azimuth) was simulated using successive stimuli with dynamically changing interaural intensity differences presented via earphones. The mechanisms underlying a specific sensitivity of neurons to the direction of motion were investigated using microiontophoretic application of γ-aminobutyric acid (GABA) and the GABAA receptor antagonist bicuculline methiodide (BMI). In the first part of the study, responses of a total of 152 neurons were recorded. Seventy-one percent of sampled neurons were motion-direction sensitive. Two types of responses could be distinguished. Thirty-four percent of neurons showed a directional preference exhibiting stronger responses to one direction of motion. Fifty-seven percent of neurons responded with a shift of spatial receptive field position depending on the direction of motion. Both effects could occur in the same neuron depending on the parameters of apparent motion. Most neurons with contralateral receptive fields exhibited directional preference only with motion entering the receptive field from the opposite direction (i.e. the ipsilateral part of the azimuth). Receptive field shifts were opposite to the direction of motion. Specific combinations of spatio-temporal parameters determined the motion-direction-sensitive responses. Velocity was not encoded as a specific parameter. Temporal parameters of motion and azimuthal position of the moving sound source were differentially encoded by neurons in different fields of auditory cortex. Neurons with a directional preference in the dorsal fields can encode motion with short interpulse intervals, whereas direction preferring neurons in the primary field can best encode motion with medium interpulse intervals. Furthermore, neurons with a directional preference in the dorsal fields are specialized for encoding motion in the midfield of azimuth, whereas direction preferring neurons in the primary field can encode motion in lateral positions. In the second part of the study, responses were recorded from additional 69 neurons. Microiontophoretic application of BMI influenced the motion-direction sensitivity of 53 % of neurons. In 21 % of neurons the motion-direction sensitivity was decreased by BMI by decreasing either directional preference or receptive field shift. In neurons with a directional preference, BMI increased the spike number for the preferred direction in about the same amount as for the non-preferred direction. Thus, inhibition was not direction specific. In contrast, BMI increased motion-direction sensitivity by either increasing directional preference or magnitude of receptive field shifts in 22 % of neurons. An additional 10 % of neurons changed their response from a receptive field shift to a directional preference under BMI. In these 32 % of neurons, the observed effects could often be better explained by adaptation of excitation than by inhibition. The results suggest, that motion information is differentially processed in different fields of the auditory cortex of the rufous horseshoe bat. Thus, functionally organized pathways for the processing of different parameters of auditory motion seem to exist. The fact that cortex specific GABAergic inhibition contributes to motion-direction sensitivity in at least a part of cortical neurons is supportive for the notion that the auditory cortex plays an important role in further processing the neural responses to apparent motion brought up from lower levels of the auditory pathway.

Sun, 1 Jan 1995 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3195/ http://epub.ub.uni-muenchen.de/3195/1/3195.pdf Radtke-Schuller, Susanne; Schuller, Gerd Radtke-Schuller, Susanne und Schuller, Gerd (1995): Auditory cortex of the rufous horseshoe bat. 1. Physiological response properties to acoustic stimuli and vocalizations and the topographical distribution of neurons. In: European Journal of Neuroscience, Vol. 7: pp. 570-591. Biologie

Tue, 1 Jan 1991 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3193/ http://epub.ub.uni-muenchen.de/3193/1/3193.pdf Schuller, Gerd; O'Neill, W. E.; Radtke-Schuller, Susanne Schuller, Gerd; O'Neill, W. E. und Radtke-Schuller, Susanne (1991): Facilitation and delay sensitivity of auditory cortex neurons in CF-FM bats, Rhinolopus rouxi and Pteronotus p. parnellii. In: European Journal of Neuroscience, Vol. 3, Nr. 11: pp. 1165-1181

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.16.045021v1?rss=1 Authors: Neymotin, S. A., Barczak, A., O'Connell, M. N., McGinnis, T., Markowitz, N., Espinal, E., Griffith, E., Anwar, H., Dura-Bernal, S., Lytton, W. W., Jones, S. R., Bickel, S., Lakatos, P. Abstract: Electrophysiological oscillations in neocortex have been shown to occur as multi-cycle events, with onset and offset dependent on behavioral and cognitive state. To provide a baseline for state-related and task-related events, we quantified oscillation features in resting-state recordings. We used two invasively-recorded electrophysiology datasets: one from human, and one from non-human primate auditory system. After removing event related potentials, we used a wavelet transform based method to quantify oscillation features. We identified about 2 million oscillation events, classified within traditional frequency bands: delta, theta, alpha, beta, gamma, high gamma. Oscillation events of 1-44 cycles were present in at least one frequency band in 90% of the recordings, consistent across human and non-human primate. Individual oscillation events were characterized by non-constant frequency and amplitude. This result naturally contrasts with prior studies which assumed such constancy, but is consistent with evidence from event-associated oscillations. We measured oscillation event duration, frequency span, and waveform shape. Oscillations tended to exhibit multiple cycles per event, verifiable by comparing filtered to unfiltered waveforms. In addition to the clear intra-event rhythmicity, there was also evidence of inter-event rhythmicity within bands, demonstrated by finding that coefficient of variation of interval distributions and Fano Factor measures differed significantly from a Poisson distribution assumption. Overall, our study demonstrates that rhythmic oscillation events dominate auditory cortical dynamics. Copy rights belong to original authors. Visit the link for more info