Just to prove that this site is about more than anatomy, here is a neurophysiology question for Year 2 students:
Administration of an experimental drug that acts on
A. faster
B. larger
C. slower
D. smaller
E. unchanged
Correct answer and explanation will be posted next week.
3 comments:
We haven't actually covered this yet, but I've found the formula for the length constant and I would say that if the constant is increased it means that the resistance across the membrane is raised i.e. conduction should be slower.
Correct?
I'm the same one of the comment above. I've been thinking further on this blessed length constant and effectively I should say that increasing would make the APs faster as if you are increasing myelination. But I'm still not sure. Not even our neuroscience very expensive book mentions this thing.
The correct answer is A. Well done for working it out.
The space constant of an axon reflects the amount of passive spread of current within an axon. The larger the space constant, the further the current can spread, allowing action potentials to propagate faster. This is why myelin increases the conduction velocity of action potentials down an axon. Conversely, demyelination decreases the space constant and slows action potential conduction.
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