neuron energy use

Luke Sjulson luke.sjulson at jhu.edu
Tue Oct 27 01:43:05 EST 1998


> > The following questions assume the above conception is correct.
> > * What happens if a neuron is heavily stimulated with messages from its
> > dendrites, but there is not enough energy in the local bloodstream to increase
> > the firing rate very much?
> 
> Happens all the time.  They are called refractory periods in which a neuron cannot
> fire again.  But I think you mean what happens in the case of a lack of energy.

	There are refractory periods, but these are due to 'inactivation' of
voltage-gated sodium channels (and to some extent, K+ efflux, but that
supposedly is more significant in the squid axons where this was figured
out than it is in myelinated human ones), not the neuron running out of
energy.  
	Another thing is that when the original poster talks about "energy" in
the local bloodstream, I think he's under the assumption that blood flow
to the neuron has to increase first in order for firing rate to change,
but neurons operate anerobically for a bit, and blood flow increases a
few seconds after firing rate increases (there's a short time lag when
they measure this in fMRI).
	
hope this helps,

Luke Sjulson
luke.sjulson at jhu.edu



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