Podcasts about action potential

Play Episode Listen Later Apr 16, 2023

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.16.537084v1?rss=1 Authors: Lipkin, A. M., Bender, K. J. Abstract: Neurons are remarkably polarized structures: dendrites spread and branch to receive synaptic inputs while a single axon extends and transmits action potentials to downstream targets. Neuronal polarity is maintained by the axon initial segment (AIS), a region between the soma and axon proper that is also the site of action potential (AP) generation. This polarization between dendrites and axons extends to inhibitory neurotransmission. In adulthood, the neurotransmitter GABA hyperpolarizes dendrites but instead depolarizes axons. These differences in function collide at the AIS. Multiple studies have shown that GABAergic signaling in this region can share properties of either the mature axon or mature dendrite, and that these properties evolve over a protracted period encompassing periadolescent development. Here, we explored how developmental changes in GABAergic signaling affect AP initiation. We show that GABA at the axon initial segment inhibits action potential initiation in Layer 2/3 pyramidal neurons in prefrontal cortex from mice of either sex across GABA reversal potentials observed in periadolescence. These actions occur largely through current shunts generated by GABAA receptors and changes in voltage-gated channel properties that affected the number of channels that could be recruited for AP electrogenesis. These results suggest that GABAergic neurons targeting the axon initial segment provide an inhibitory "veto" across the range of GABA polarity observed in normal adolescent development, regardless of GABAergic synapse reversal potential. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

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Mitochondria induce anisotropy and delays in action potential conduction

Neural Implant podcast - the people behind Brain-Machine Interface revolutions

Play Episode Listen Later Mar 28, 2023

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.03.28.534468v1?rss=1 Authors: Alcami, P., Castelfranco, A. Abstract: The internal resistance of axons to ionic current flow affects the speed of action potential propagation. As biological cables, axons contain mitochondria which are necessary to support axonal function with energy supply. Although we would expect mitochondria to increase the internal resistance to current flow, their impact on the conduction velocity of action potentials has remained elusive. To investigate the impact of mitochondria on action potential propagation in the small non-myelinated fibers found in the vertebrate brain, we combined computational modeling and electron microscopy from the axons found in the premotor pathway that controls the production of birdsong with submillisecond precision. Mitochondria occupancy of axonal cross-sections ranged from 5 to 73% (average: 29%) in the ~ 0.2-0.7 m diameter non-myelinated axons connecting song premotor nuclei HVC and RA in canaries. Interestingly, this occupancy depends on axonal diameter: axonal cross-section occupancy by mitochondria was larger in small axons, with an average occupancy of ~46% for axons with diameters smaller than 300 nm and ~21% for larger diameters. Computational modeling showed that when the propagating action potential meets a mitochondrion, the conduction velocity decreases and the action potential is delayed by tenths of microseconds to microseconds. This effect is stronger in small axons given their larger cross section mitochondrial occupancy and cumulates delays of tenths of milliseconds along the whole pathway linking HVC and RA. Finally, we modeled the impact of varying densities of mitochondria on action potential propagation along the songbird premotor pathway. In summary, our model shows that axonal mitochondria induce the anisotropic propagation of action potentials, and that this effect cumulates a typical delay in the order of tenths of milliseconds over distances of mms. By partially occupying axoplasm, mitochondria constitute a biological design constraint that delays information processing in the small-diameter unmyelinated axons found in the vertebrate brain. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

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Suraj Mudichintala on investing in bioelectronic medicine companies with Action Potential Venture

Play Episode Listen Later Mar 27, 2023 29:18

Suraj Mudichintala is a Senior Associate at Action Potential Capital which is GSK's bioelectronic medicine venture fund. Top 3 Takeaways: "Our fund is different in that we invest actually directly off of GSK's balance sheet. So we're what's called an evergreen fund where we don't actually have a fund size" "The way that I think about it is that a VC is really paid to allocate capital but really is really paid to think. You really have to think about what is the next space or the next technology that could disrupt a space? And because of that, it's a much you often have to take a much more longitudinal view. And it takes a lot of patience and tracking a space oftentimes for years" "When you reach out to a VC having a pitch, first of all, sending a non-confidential pitch deck is mandatory, I think. And that deck is essentially where we're making the first decision as to whether or not to do a call with you" 0:45 Do you want to introduce yourself better than I just did? 1:15 "Do you wanna talk about Action Potential, what it is, who it was formed by, and the investment thesis?" 2:30 Do you want to talk about the expansion of the AP investment thesis? 4:30 What does traditional Venture Capital look like and how is it different in that you are funded by GSK? 6:15 What do the positions within a VC firm look like? 7:45 How has it been for you going from Analyst to Associate? 8:45 What does your due diligence look like? 11:45 "A lot of VCs have a target size range, be it seed or angel or, maybe larger institutional stuff. But it sounds like you guys don't really have that?" 12:45 "How did you get into this space?" 14:45 "So how does consulting compare to the VC life?" 18:45 "What would you suggest is the best way to get your attention?" 24:00 What are some tips and tricks to reaching out to you? 27:00 What was the worst pitch deck you ever saw? 28:30 " Is there anything that we didn't talk about that you wanted to mention?"

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Cardiovascular | Myocardial Action Potential

The Medbullets Step 1 Podcast

Play Episode Listen Later Mar 15, 2023 12:09

In this episode, we review the high-yield topic of Myocardial Action Potential from the Cardiovascular section. Follow Medbullets on social media: Facebook: www.facebook.com/medbullets Instagram: www.instagram.com/medbulletsofficial Twitter: www.twitter.com/medbullets --- Send in a voice message: https://anchor.fm/medbulletsstep1/message

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Stiles-Nicholson STEM Teacher Academy and Neuroscience at FAU Jupiter: What's your "Action Potential"?

Once An Owl, Always An Owl

Play Episode Listen Later Sep 28, 2022 31:34

In today's episode, we will hear from Pilar Taylor, the Director of the Stiles-Nicholson STEM Teacher Academy. Founded by David Nicholson of the Stiles-Nicholson Foundation, the Academy provides educators structured access to the high-caliber research environment of the FAU Lab Schools. She will share information about the scheduled workshops during the 2022-2023 school year, for educators in Palm Beach County. You will also hear from Mia and Luna volunteers for the ASCEND program in Jupiter ASCEND (Advancing STEM: Community Engagement through Neuroscience Discovery). Mia Vila is majoring in cellular neuroscience and participates in undergraduate research studying to understand the neurobiological and behavioral effects of substance abuse disorder. Luna Forero has been an ADHUS owl since Kindergarten and will be a legacy student once she graduates in the spring. She is on track to graduate with her bachelor of science with a biological chemistry concentration. Her research is Through the social neuroscience lens, which focuses on supporting underrepresented students in STEM by investigating stereotype threats. If you are interested in exploring the professional learning opportunities offered by the Stiles-Nicholson STEM Teacher Academy, email: SNSTA@fau.edu or at STILES-NICHOLSON STEM TEACHER ACADEMY

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Probing Action Potential Generation and Timing under Multiplexed Basal Dendritic Computations Using Two-photon 3D Holographic Uncaging

Play Episode Listen Later Sep 27, 2022

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.09.26.509562v1?rss=1 Authors: Xiao, S., Yadav, S., Jayant, K. Abstract: Basal dendrites of layer 5 cortical pyramidal neurons exhibit Na+ and NMDAR spikes, and are uniquely poised to influence somatic output. Nevertheless, due to technical limitations, how multibranch basal dendritic integration shapes action-potential output remains poorly mapped. Here, we combine 3D two-photon holographic transmitter-uncaging, whole-cell dynamic-clamp, and biophysical modeling, to reveal how synchronously activated synapses (distributed and clustered) across multiple basal dendritic branches impacts action-potential generation, under quiescent and in vivo like conditions. While dendritic Na+ spikes promote milli-second precision, distributed inputs and NMDAR spikes modulate firing rates via axo-somatic persistent sodium channel amplification. Action-potential precision, noise-enhanced responsiveness, and improved temporal resolution, were observed under high conductance states, revealing multiplexed dendritic control of somatic output amidst noisy membrane-voltage fluctuations and backpropagating spikes. Our results unveil a critical multibranch integration framework in which a delicate interplay between distributed synapses, clustered synapses, and axo-somatic subthreshold conductances, dictates somatic spike precision and gain. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

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Computational Modeling of the Human Compound Action Potential

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Play Episode Listen Later Aug 26, 2022

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.08.26.505458v1?rss=1 Authors: Alamri, Y., Jennings, S. Abstract: The auditory nerve (AN) compound action potential (CAP) is an important tool for assessing auditory disorders and monitoring the health of the auditory periphery during surgical procedures. The CAP has been mathematically conceptualized as the convolution of a unit response (UR) waveform with the firing rate of a population of AN fibers. Here, an approach for predicting experimentally recorded CAPs in humans is proposed, which involves the use of human-based computational models to simulate AN activity. CAPs elicited by clicks, chirps, and amplitude-modulated carriers were simulated and compared with empirically recorded CAPs from human subjects. In addition, narrowband CAPs derived from noise-masked clicks and tone bursts were simulated. Many morphological, temporal, and spectral aspects of human CAPs were captured by the simulations for all stimuli tested. These findings support the use of model simulations of the human CAP to refine existing human-based models of the auditory periphery, aid in the design and analysis of auditory experiments, and predict the effects of hearing loss, synaptopathy, and other auditory disorders on the human CAP. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

Noumena - Action Potential (Original Mix)

Mirror Sessions

Play Episode Listen Later Jul 30, 2022 5:56

Buy or Stream: Beatport: https://www.beatport.com/release/first-light/3788277 Spotify: ABOUT THIS RELEASE: The 'First Light' EP represents a journey of self-discovery. Simple but smooth and catchy melodies and synths meet large, loud and powerful sounds with a dystopian atmosphere, driven by minimalistic but sharp drums and basslines. The first track, 'Action Potential' co-occured with an exceptionally inspiring period of my life where I felt that a sudden burst of energy has emerged from the previously long-lasting calm, which has been running within me ever since. The second track, 'Persona', tells the story of how this momentum occasionally gets interrupted by difficulties and confusions that always keep returning - but how it also never seizes to exist even in times when it seems to have disappeared for good. With a balanced harmony between light and dark; calm and energetic; soothing and disturbing - these two tracks are aimed both at speaking to your soul and making your body move. MORE ABOUT THIS ARTIST: https://soundcloud.com/david-csomor-508459507 https://www.instagram.com/noumenamusic/ FOLLOW OUR AMAZING TECHNO PLAYLIST ON SPOTIFY: https://spoti.fi/2WfuRNm MORE ABOUT BLACK MIRROR RECORDINGS: Our linktree: https://linktr.ee/blackmirrorrecordings For more info check: https://www.blackmirrorrecordings.com/ Instagram: https://www.instagram.com/blackmirrorrecordings/ Facebook: https://www.facebook.com/blackmirrorrecordings/ Send your demo: demo@blackmirrorrecordings.com

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055 - Don't get addicted to crack with Chase Davidson of Action Potential Rehab

The Health Hustle - Austin Texas

Play Episode Listen Later Jul 14, 2022 47:57

Chase Davidson of Action Potential Rehab is all about giving with no expectations. In This Episode: 02:17 - Why Chase decided to be a chiropractor 06:50 - The chiro divide 09:10 - The patient mill 13:50 - Don't get addicted to crack 17:00 - Breaking free from the corporate world 21:20 - Add value with no expectation 23:00 - Being the immediate solution 25:30 - Staying top of mind 29:30 - Abundance mindset 32:20 - His most expensive business mistake 34:20 - Swinging the success pendulum 37:40 - The best part about entrepreneurship 41:30 - Why he moved to Austin 46:00 - Prioritize relationships 3-Tip Tuesday's - Health & Fitness Marketing Tips! Get all links, resources, and show notes at: www.coreyhi.com/podcast/055

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Episode 23 "New Identity, Legal Action, Potential Cities and Coaches"

Let's Talk XFL

Play Episode Listen Later Apr 11, 2022 58:42

This week Michael provides a rundown of XFL developments: Dany Garcia & Dwayne "The Rock" Johnson's teasers, XFL's social media & website Blackout, scouting update, the BIG announcement, Terrell Buckley hiring, legal trouble, NFT's, Showcases and is joined by Mike Mitchell to discuss his recent article on potential cities and coaches.Code: LETSTALKXFLhttps://www.503-sports.com?aff=22

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The Action Potential Model

Just Under Ideal

Play Episode Listen Later Mar 4, 2022 7:49

Like a neuron, you either grabbed my attention or you didn't.

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Episode 79 - Cephalopods

Breaking Bad Science

Play Episode Listen Later Dec 27, 2021 31:25

We'd love to hear from you (feedback@breakingbadscience.com)Look us up on social media Facebook: https://www.facebook.com/groups/385282925919540Instagram: https://www.instagram.com/breakingbadsciencepodcast/Website: http://www.breakingbadscience.com/Patreon: https://www.patreon.com/breakingbadscienceIf spongebob taught us anything it's that seafaring creatures are…not intelligent at all. Fortunately, we have science and it turns out cephalopods and even decapods have a type of intelligence that we're only beginning to understand. Join hosts Shanti and Danny as we discuss the fascinating creatures we know as cephalopods and why their intelligence is or ever was really in question.ReferencesVendetti, J.; The Cephalopoda. Berkeley. 2006. https://ucmp.berkeley.edu/taxa/inverts/mollusca/cephalopoda.phpSeabrook, A.; The Story of an Octopus Named Otto. NPR. 02-Nov-2008. https://www.npr.org/templates/story/story.php?storyId=96476905Davis, H.; Resting and Action Potential of Squid Giant Axons Intracellularly Perfused with Sodium-Rich Solutions. PNAS. 31-Jul-1963. 50 (619 - 626). https://www.pnas.org/content/pnas/50/4/619.full.pdfBirch, J., et. al.; Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans. London School of Economics and Political Science. Nov-2021. https://www.lse.ac.uk/News/News-Assets/PDFs/2021/Sentience-in-Cephalopod-Molluscs-and-Decapod-Crustaceans-Final-Report-November-2021.pdfSupport the show (https://www.patreon.com/breakingbadscience?fan_landing=true)

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Episode 43: Juan Cueva, Investor at Action Potential Venture Capital --- Big Pharma Creates an Early Stage Corporate Venture Medtech Fund: The Mission of Bioelectronics

Medtech Money Podcast

Play Episode Listen Later Dec 1, 2021 63:30

In this episode, Giovanni and Juan discuss how the name of Action Potential Venture Capital came about, what kind of technology they focus in and how they choose their investments, what round they prefer to invest, how does being a corporate venture capital firm acting as traditional venture capital group affect their investment, and more. Juan Cueva LinkedIn Action Potential Venture Capital Website Giovanni Lauricella LinkedIn Project Medtech LinkedIn Project Medtech Website

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Medtech Money --- Episode 43: Juan Cueva, Investor at Action Potential Venture Capital --- Big Pharma Creates an Early Stage Corporate Venture Medtech Fund: The Mission of Bioelectronics

Project Medtech

Play Episode Listen Later Dec 1, 2021 63:30

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How Gratitude Effects Your Brain

Action Potential Podcast

Play Episode Listen Later Nov 25, 2021 10:02

Welcome to the Action Potential podcast! In this episode, Dr. Sabrina Segal shows you what the practice of gratitude can do for your brain. Learn how gratitude practice has been scientifically shown to improve your mental wellness and combat depression and anxiety!

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Francois Ladouceur on a new paradigm for action potential sensing through optics

Neural Implant podcast - the people behind Brain-Machine Interface revolutions

Play Episode Listen Later Oct 25, 2021 28:13

Francois Ladouceur is a University of New South Wales professor teaching and researching integrated optics, silica and diamond-based photonics, optical sensing networks, and photonics-based brain/machine interfaces Top 3 Takeaways: "it's a liquid crystal-based transducer that can transduce an electrical signal into an optical signal that we can carry the away from the place of measurement" With electrical-based electrodes making the devices smaller increases the impedance degrading the signal which doesn't happen in LCP based electrodes "We have built a chip, which is bidirectional, it can read the action potential and it can stimulate the neuron. Again, entirely passive. It requires no electrical input. It does not dissipate energy." 0:30 "How did you get on this podcast?" 3:00 Is another advantage the lack of heat generated? 5:30 "What are the bio compatible properties of liquid crystal?" 7:00 "What are some advantages of this over other techniques?" 10:15 "How does the multiplexer work?" 15:15 "What would be the minimum width?" 19:00 "You haven't really published too much about this, but you said a big paper is going to be coming out?" 21:30 "It's really just for sensing, you couldn't stimulate with these, right?" 25:00 "When did this technology originally come to your mind?" 27:15 "Is there anything that we didn't talk about that you wanted to mention?"

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Action Potential 31 05 21

challenging action potential

Play Episode Listen Later May 31, 2021 25:41

Challenging self summary this week but an interesting one, talk of currant psychical state, some modelling stuff, and recent drawings.

Naked Body: Getting on our nerves

The Naked Body, from the Naked Scientists

Play Episode Listen Later May 21, 2021 3:14

Our brains run on electricity, but how does that electricity work to send messages around the body? Isabelle Cochrane gives us a tour of the body's information highways... Like this podcast? Please help us by supporting the Naked Scientists

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Action Potential with Dylan Gutierrez

The Arts Today

Play Episode Listen Later Apr 23, 2021 54:32

Over the course of this historic pandemic period that has now engrained itself into our definitions of normalcy, sometimes it feels like all we can do is watch the events of the world from the metaphorical passenger seat. Whether we are talking about the damage that has been done to the global live arts and culture industries, or the social events happening within our societies that cannot be ignored, it can be easy to feel like we are just an unwitting passenger on this journey of uncertainty. How can we take a primary position of action in the middle of all of this? Join me as I sit down with Dylan Gutierrez, a principal dancer with the Joffrey Ballet, and co-founder and director of Action Lines, a new ballet company that Dylan helped create. We discuss how in the middle of so much chaos, Dylan was able to take a position of action within the arts world, and the potential of his new company to redefine how we see the arts. Please enjoy.

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Action Potential

Play Episode Listen Later Apr 22, 2021 12:20

Hertzog Review and May prediction

Action Potential Hertzog S and D

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Play Episode Listen Later Apr 22, 2021 15:48

Title

hertzog action potential

Investing into Healthcare & Latinx VC with Juan-Pablo Mas, Partner at Action Potential VC

Divergent Unicorns

Play Episode Listen Later Feb 8, 2021 34:41

On this episode we chat with Juan-Pablo Mas, who is a Partner at Action Potential VC; which is a growth stage venture firm investing into Healthcare. Juan-Pablo also is a founding board member of Latinx VC. Topics to look forward to... due diligence of healthcare startups, COVID-19's impact on healthcare startups, and increasing diverse representation in venture capital. Visit our website and submit a question/topic here. Hosted by @de_havia and @imessien Recorded: September 2020

Action Potential Ep4

Play Episode Listen Later Feb 4, 2021 5:25

Ep 4

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The stress-induced Neural Network tracks Kantian Epistemology through characteristic action potential and neuromodulator/neurotransmitter phenomenology. Dr Guerra 13 JAN 2021.

Authentic Biochemistry

Play Episode Listen Later Jan 14, 2021 28:58

LC axonal projections to the mPFC modulate a diversity of cognitive processes, including working memory, sustained attention, and flexible attention and under moderate rates of LC activity and NE release, high-affinity postsvnaptic α2 adrenergic receptors in the PFC are preferentially engaged and promote working memory However, with elevated LC firing and activation of lower affinity α1 adrenergic receptors, working memory is impaired while agentic focused attention becomes prominent so it seems that LC projections to the PFC modulate different cognitive processes in a context-sensitive manner. his latter mechanism could correlate with the experienced rapid response such as in “fight or flee” decision making upon immediate threatening danger. The sensation perception recognition and response behaviour all works sequentially from these neuronal loci post encounter to the stimulus and as such fit well into Kantian epistemology which obtains that the individual is presented with a particular stimulus-sense data or “intuition” that is processed by the faculty of the understanding as a perception of danger in association with a concept-abstracted from previous experience. This representation is then acted upon and the neural network-already poised to respond sequentially follows suit and ultimately directs the motor cortex to act. DONATE TO AUTHENTIC BIOCHEMISTRY TODAY!!!!!! --- Send in a voice message: https://anchor.fm/dr-daniel-j-guerra/message Support this podcast: https://anchor.fm/dr-daniel-j-guerra/support

Pacemaker Action Potential

First Past the Post

Play Episode Listen Later Jan 1, 2021 2:02

This episode covers the pacemaker action potential!

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Ventricular Action Potential

First Past the Post

Play Episode Listen Later Dec 31, 2020 1:22

This episode covers the ventricular action potential!

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Action Potential ep3

Play Episode Listen Later Dec 24, 2020 12:27

Long overdue, and quickly assembled 3rd entry to close a busy year.

μ Opioid Receptors Modulate Action Potential Kinetics and Firing Frequency in Neocortical Interneurons

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Play Episode Listen Later Nov 20, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.20.391508v1?rss=1 Authors: Dutkiewicz, A. P., Morielli, A. D. Abstract: The endogenous opioid system of the cerebral cortex is an important feature of antinociception and reward valuation through its modulation of inhibitory neocortical interneurons. Dysregulation of this system, through disease or drugs, disrupts the reward system and contributes to eating and mood disorders, impulsive actions, and addiction. Impulsive behaviors can be induced experimentally through infusion of the opioid receptor specific agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) into the frontal cortex in animal models. The mechanism involves increased potassium channel function, which suppresses neocortical interneuron activity. However, much of the data on the effect of this receptor on ion channels have been derived from noncortical ORs, and the identity and effects of the ion channels that the OR targets in neocortical neurons have not been thoroughly investigated. Based on previous experiments by other labs, we hypothesized that the OR could activate -dendrotoxin (-DTX) sensitive channels (Kv1.1, Kv1.2, and Kv1.6 subunits) to exert its inhibitory effects in cortical interneurons. This, in turn, is expected to confer a variety of effects on passive and active electrical properties of the cell. We performed patch-clamp electrophysiology to examine the electrophysiological effects of ORs in cultured neocortical interneurons. We found that a range of features among the 54 membrane and action potential properties we analyzed were modulated by ORs, including action potential kinetics and frequency. The Kv1.1, Kv1.2, and Kv1.6 inhibitor -DTX reversed some effects on action potential frequency, but not effects on their kinetics. Therefore, ORs in neocortical interneurons influence -DTX-sensitive channels, as well as other channels, to modulate action potential kinetics and firing properties. Copy rights belong to original authors. Visit the link for more info

Top-down acetylcholine enables social discrimination via unlocking action potential generation in olfactory bulb vasopressin cells

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Play Episode Listen Later Nov 9, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.11.09.373845v1?rss=1 Authors: Suyama, H., Egger, V., Lukas, M. Abstract: Social discrimination in rats requires activation of the intrinsic bulbar vasopressin system, but it is unclear how this system comes into operation. Here we show that a higher number of bulbar vasopressin cells (VPC) is activated by stimulation with a conspecific compared to rat urine, indicating that VPC activation depends on more than olfactory cues during social interaction. In-vitro slice electrophysiology combined with pharmacology and immunohistochemistry then demonstrated that centrifugal cholinergic inputs from the diagonal band of Broca can enable olfactory nerve-evoked action potentials in VPCs via muscarinic neuromodulation. Finally, such muscarinic activation of the vasopressin system is essential for vasopressin-dependent social discrimination, since recognition of a known rat could be blocked by a muscarinic antagonist and rescued by additional application of vasopressin. For the first time, we demonstrated that top-down cholinergic modulation of bulbar VPC activity in a social context is crucial for individual social discrimination in rats. Copy rights belong to original authors. Visit the link for more info

Affirmative Action Potential

Falling Down with David Han

Play Episode Listen Later Oct 21, 2020

This week I talk about firing a shotgun for the first time ever, having a life too big for a station wagon, and California's further descent into retardation. I thought I would keep this under 20 minutes but I seemingly couldn't STFU.

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Action potential-coupled Rho GTPase signaling drives presynaptic plasticity

Play Episode Listen Later Oct 8, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.07.330126v1?rss=1 Authors: Dube, S., Racz, B., Brown, W. E., Gao, Y., Soderblom, E. J., Yasuda, R., Soderling, S. H. Abstract: In contrast to their postsynaptic counterparts, the contributions of activity-dependent cytoskeletal signaling to presynaptic plasticity remain controversial and poorly understood. To identify and evaluate these signaling pathways, we conducted a proteomic analysis of the presynaptic cytomatrix using in vivo biotin identification (iBioID). The resultant proteome was heavily enriched for actin cytoskeleton regulators, including Rac1, a Rho GTPase that activates the Arp2/3 complex to nucleate branched actin filaments. Strikingly, we find Rac1 and Arp2/3 are closely associated with presynaptic vesicle membranes and negatively regulate synaptic vesicle replenishment at both excitatory and inhibitory synapses. Using optogenetics and fluorescence lifetime imaging, we show this pathway bidirectionally sculpts short-term synaptic depression and that its presynaptic activation is coupled to action potentials by voltage-gated calcium influx. Thus, this study provides a new proteomic framework for understanding presynaptic physiology and uncovers a previously unrecognized mechanism of actin-regulated short-term presynaptic plasticity that is conserved across cell types. Copy rights belong to original authors. Visit the link for more info

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Voltage-gated potassium channels ensure action potential shape fidelity in distal axons

PaperPlayer biorxiv biophysics

Play Episode Listen Later Sep 15, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.15.297895v1?rss=1 Authors: Gonzalez Sabater, V., Rigby, M., Burrone, J. Abstract: The initiation and propagation of the action potential (AP) along an axon allows neurons to convey information rapidly and across distant sites. Although AP properties have typically been characterised at the soma and proximal axon, the propagation of APs towards distal axonal domains of mammalian neurons remains limited. We used Genetically Encoded Voltage Indicators (GEVIs) to image APs simultaneously at different locations along the long axons of dissociated hippocampal neurons with sub-millisecond temporal resolution. We found that APs became sharper and showed remarkable fidelity as they traveled towards distal axons, even during a high frequency train. Blocking voltage-gated potassium channels (Kv) with 4-AP resulted in an increase in AP width in all compartments, which was stronger at distal locations and exacerbated during AP trains. We conclude that the higher levels of Kv channel activity in distal axons serves to sustain AP fidelity, conveying a reliable digital signal to presynaptic boutons. Copy rights belong to original authors. Visit the link for more info

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Self-similar action potential cycle-to-cycle variability of Ca2+ and current oscillators in cardiac pacemaker cells

Play Episode Listen Later Sep 2, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.01.277756v1?rss=1 Authors: Yang, D., Lyashkov, A. E., Morrell, C. H., Zahanich, I., Yaniv, Y., Vinogradova, T. M., Ziman, B. D., Maltsev, V. A., Lakatta, E. G. Abstract: Variability of heart pacemaker cell action potential (AP) firing intervals (APFI) means that pacemaker mechanisms do not achieve equilibrium during AP firing. We tested whether mechanisms that underlie APFI, in rabbit sinoatrial cells are self-similar within and across the physiologic range of APFIs effected by autonomic receptor stimulation. Principal Component Analyses demonstrated that means and variabilities of APFIs and local Calcium releases kinetics, of AP induced Calcium-transient decay times, of diastolic membrane depolarization rates, of AP repolarization times, of simulated ion current amplitudes, are self-similar across the broad range of APFIs (264 to 786 ms). Further, distributions of both mean APFIs and mean Calcium Variability of heart pacemaker cell action potential (AP) firing intervals (APFI) means that pacemaker mechanisms do not achieve equilibrium during AP firing. We tested whether mechanisms that underlie APFI, in rabbit sinoatrial cells are self-similar within and across the physiologic range of APFIs effected by autonomic receptor stimulation. Principal Component Analyses demonstrated that means and variabilities of APFIs and local Calcium releases kinetics, of AP induced Calcium-transient decay times, of diastolic membrane depolarization rates, of AP repolarization times, of simulated ion current amplitudes, are self-similar across the broad range of APFIs (264 to 786 ms). Further, distributions of both mean APFIs and mean Calcium and membrane potential dependent coupled-clock function kinetics manifested similar power law behaviors across the physiologic range of mean APFIs. Thus, self-similar variability of clock functions intrinsic to heart pacemaker cells determines both the mean APFI and its interval variability, and vice versa. and membrane potential dependent coupled-clock function kinetics manifested similar power law behaviors across the physiologic range of mean APFIs. Thus, self-similar variability of clock functions intrinsic to heart pacemaker cells determines both the mean APFI and its interval variability, and vice versa. Copy rights belong to original authors. Visit the link for more info

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Mini Episode 2- The Saga of the Cardiac Action Potential

The Poison Lab

Play Episode Listen Later Aug 26, 2020 15:27

Action potentialSodium/Potassium ATPase pumps create more positively charged ions outside the cell than inside the cell, this creates a relative negative charge in the cellPhase 4- Resting (~ -90 mv)Phase 0- Sodium enters the cell (+10 mv) Phase 1- Potassium efflux from cell as now there is no negative charge holding it in (0 mv) Phase 2- Calcium channels open and allow calcium in, calcium triggers the ryandoine receptor and allows for calcium dependent calcium release from the sarcoplasmic reticulum occursPhase 3- Potassium continues to leave the cell allowing return to -90 mv

phase saga resting cardiac calcium sodium potassium action potential

Optically pumped magnetometers disclose magnetic field components of the muscular action potential.

Play Episode Listen Later Jul 31, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.30.228882v1?rss=1 Authors: Broser, P., Middelmann, T., Sometti, D., Braun, C. Abstract: Aim: To track the magnetic field generated by the propagating muscle action potential (MAP). Method: In this prospective, proof of principle study, the magnetic activity of the intrinsic foot muscle after electric stimulation of the tibial nerve was measured using optically pumped magnetometers (OPMs). A classical biophysical electric dipole model of the propagating MAP was implemented to model the source of the data. Results: The signal profile generated by the activity of the intrinsic foot muscles was measured by four OPM devices. Three devices were located above the same muscle to compare the direction and the strength of the magnetic signal while propagating along the muscle. Interpretation: OPM devices allow for a new, non-invasive way to study MAP patterns. Since magnetic fields are less altered by the tissue surrounding the dipole source compared to electric activity, a precise analysis of the spatial characteristics and temporal dynamics of the MAP is possible. The classic electric dipole model explains major but not all aspects of the magnetic field. The field has longitudinal components generated by intrinsic structures of the muscle fibre. By understanding these magnetic components, new methods could be developed to analyse the muscular signal transduction pathway in greater detail. Copy rights belong to original authors. Visit the link for more info

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Fragile X Mental Retardation Protein modulates somatic D-type K+ channels and action potential threshold in the mouse prefrontal cortex

AJP-Heart and Circulatory Podcasts

Play Episode Listen Later Jul 30, 2020

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.30.228874v1?rss=1 Authors: Kalmbach, B., Brager, D. H. Abstract: Axo-somatic K+ channels control action potential output in part by acting in concert with voltage-gated Na+ channels to set action potential threshold. Slowly inactivating, D-type K+ channels are enriched at the axo-somatic region of cortical pyramidal neurons of the prefrontal cortex where they regulate action potential firing. We previously demonstrated that D-type K+ channels are down regulated in extratelencephalic-projecting L5 neurons (ET) in the prefrontal cortex of the fmr1 knockout mouse model of Fragile X syndrome (FX mice), resulting in a hyperpolarized action potential threshold. To test whether K+ channel alterations are regulated in a cell autonomous manner in FXS, we used a viral-mediated approach to restore expression of Fragile X Mental Retardation Protein (FMRP) in a small population of prefrontal neurons in male FX mice. Outside-out voltage clamp recordings revealed a higher D-type K+ conductance in FMRP-positive ET neurons compared to nearby FMRP-negative ET neurons. FMRP did not affect either rapidly inactivating A-type or non-inactivating K+ conductance. ET neuron patches recorded with FMRP1-298, a truncated form of FMRP which lacks mRNA binding domains, included in the pipette solution had larger D-type K+ conductance compared to heat-inactivated controls. Viral expression of FMRP in FX mice depolarized action potential threshold to near wild type levels in ET neurons. These results suggest that FMRP influences the excitability of ET neurons in the mPFC by regulating somatic D-type K+ channels in a cell autonomous, protein-protein dependent manner. Copy rights belong to original authors. Visit the link for more info

viral copy mouse protein fx channels mrna threshold somatic l5 prefrontal cortex fragile x biorxiv fxs mental retardation action potential d type

PTSD and Sympathetic Action Potential Discharge Pattern

Play Episode Listen Later May 29, 2020 17:56

Women develop post-traumatic stress disorder (PTSD) at twice the rate of men, and women with PTSD are at higher risk for developing hypertension. Yet little research has been done to date investigating the mechanisms mediating the link between PTSD and cardiovascular disease in women. The study by Yoo et al. seeks to change that. Associate Editor Donal O’Leary (Wayne State University School of Medicine) interviews lead author Qi Fu (The Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas) and expert Adam Case (University of Nebraska Medical Center) about the groundbreaking and clinically-relevant study by Fu and co-authors. The authors showed for the first time that women with PTSD had a greater pressor response during the cold pressor test compared with healthy women. What insights did Fu and collaborators uncover when they compared results from traditional methods to quantify integrated nerve signals, and a novel wavelet-based technique used to identify differences in MSNA responses to cold pressor test between women with PTSD and healthy women? Do Fu and Case anticipate that the current COVID-19 pandemic, while undeniably tragic, may eventually open new avenues of discovery for how women with PTSD differ from healthy counterparts and men? Listen and learn. Jeung-Ki Yoo, Mark B. Badrov, Mu Huang, Ryan A. Bain, Raymond P. Dorn, Elizabeth H. Anderson, Jessica L. Wiblin, Alina Suris, J. Kevin Shoemaker, Qi Fu Abnormal sympathetic neural recruitment patterns and hemodynamic responses to cold pressor test in women with posttraumatic stress disorder Am J Physiol Heart Circ Physiol, published April 27, 2020. DOI: 10.1152/ajpheart.00684.2019

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6.Equipments:sec.5-2of13-EKG and cardiac action potential

cardiac ekg equipments action potential

Play Episode Listen Later Apr 10, 2020 2:04

The EKG and the Cardiac Action Potential

5.Pharmacology2:sec.3of15-The action potential & effect ofLA

Play Episode Listen Later Apr 5, 2020 2:15

Action potential of LA

action action potential

3. Cardiac Sec.1-3of17-Cardiac Action Potential:SA Node

cardiac node action potential

Play Episode Listen Later Mar 24, 2020 6:15

SA node action potential

3.Cardiac Sec. 1-2of17-Cardiac Action Potential

Play Episode Listen Later Mar 24, 2020 2:54

Vebrricular Action Potential

cardiac action potential

#A47 (actinomyces to action potential)

The Dictionary

Play Episode Listen Later Mar 27, 2019 8:58

I read from actinomyces to action potential. dictionarypod@gmail.com https://www.patreon.com/spejampar https://www.facebook.com/thedictionarypod/ https://twitter.com/dictionarypod

Life is a Metaphor Mini Podcast

Action Potential

Play Episode Listen Later Feb 17, 2019

Why don't we see negatives and polarities in our lives as the creators of action potentials just like in science? (14 minutes)