Problem 3: Thresholds, Inactivation, and Dendrite Length Constants

In this video, I solve a problem involving thresholds, inactivation, and length constants. I made a very small mistake at around 8:30 of the video, since I didn't change the -45 below the conductance to -46. The annotation should hopefully let you guys know. The detail is fairly minor, but of course, I want to ensure that everything is perfect.

Questions? Ask me in the comments below!

[Ruben_Peter]

This video I ended up watching twice actually, just now.

The second part of the video (trial-and-error to find threshold, and then find stimulus needed at B) made a lot of sense on the first watch-through!

During the second rewatch i noticed that the equation for "you can find the resting potential as the weighted average of something something something" (at 1:48) didn't yet make intuitive sense to me; but now after pausing and thinking about a bit, I think it's starting to make sense (still doesn't feel like my understanding there is solidified at all yet, though).

Also, I think the "fold-increase" way of thinking about about changes in conductance was confusing to me (also confused me a little bit in the previous video), but that part is starting to make sense too, now! (But I think i would have a hard time explaining it in way that is actually accurate etc. if I had to do that right now)

And, I wanted to note that the equation for finding the length constant (at 10:55) wasn't intuitive to me, either. I actually was thinking about that kind of relationship during the part that where we were reading through the question/problem for the second part (around 3:28); i.e. I ended up thinking about membrane resistance and the thickness of the dendrites, and was like "huh, am I meant to think about this like an electrical wire, maybe? Probably, I guess". But I totally am not yet familiar with the derivation of those relationships/equations (the square root confused me very much at first, until i was like "oh that's probably because we need to think about cross-sectional areas and stuff"). But it was helpful seeing it just get applied, yepyep!


Anyway,
great series of videos!