Active Properties of Neurons | Responses to Current | Cable Equation in Axon Conduction
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- Опубліковано 12 чер 2024
- Neurons are always ready for change!
Building on the last video on the resting, passive properties of neurons (governed by Nernst Potential and Ohm's Law), we explore how a neuron's voltage responds to addition of current. We derive and reason through the equation for how the membrane changes in time through exponential depolarization and hyperpolarization, as a function of properties of the cell like density of channels and capacitance of the membrane.
But why are neurons so long? To quickly conduct information from one part of the body to another! The videos then introduces the Cable Equation, a partial differential equation (PDE) that describes how the voltage propagates in space when a neuron has the shape of a tube.
Playlist for all videos in series: • Introduction to Neuros...
Professor Bing Wen Brunton
www.bingbrunton.com
@bingbrunton on twitter
%%% CHAPTERS %%%
0:00 Building on RC-circuit equivalent of neurons
1:15 Membrane voltage changes in response to current
8:10 Cellular properties that change responses
10:45 Cells have shape too!
12:05 Why are neurons so long?
13:30 The axon as a cylinder, Cable Equation
20:15 Key concepts summary - Наука та технологія
Knowing about how the brain works, as a coder, was on my bucket list!
Beautifuly communicated, thank you!
Great video, but I would appreciate if you could go into more detail on *how* you arrive at specific equations and not just jumping to what it does, since that would help with my rusty math knowledge :')
At 17:40, hey, this may be some math that applies to multiple sclerosis. Besides axonal scarring, (I think) degradation of the myelin sheath should lower membrane resistance on the axon, causing lower length constant of propagation. Thanks for the content, cool stuff.
Excellent comment! Yep this is true. I talk more about MS and other degenerative myelination diseases in this video, towards the end: ua-cam.com/video/YcM7dUnp2cI/v-deo.html
Great video, keep up the great work!
So I actually have a question going back to the passive properties:
I’ve read a few articles essentially saying that EPSP rise time increases with distance from the soma (temporal filtering I think it was called). From further research it looks to me like this would be the result of an increase in the membrane time constant with this distance. But I thought the time constant wasn't supposed to depend on membrane area, ie. should be the same across the dendrite, so this idea is a bit confusing. I’ve been unable to find any resources online really explaining why this increase in rise time with distance occurs/if it does relate to the time constant. Most of them refer back to membrane capacitance but without really giving a mathematical relationship or anything.
Any help here would be much appreciated!
"Promo sm"
Ugh, I need to study some math first