neural coding of behavior: evidence for precise timing of spikes?
kate at anatomy.ucl.ac.uk
Fri Dec 8 05:52:54 EST 1995
In article otg at eis.wfunet.wfu.edu, laubach at biogfx.bgsm.wfu.edu (Mark Laubach) writes:
> Does anyone know of any study, published or unpublished, that shows
> that the precise timing of action potentials encodes information in
> the CNS?
> Specifically, I am interested in studies that used behaving subjects,
> not reduced preparations.
> My own search of the literature indicates that there is no evidence
> for precise timing of spikes as a neural code in awake, behaving
> subjects. Rather, those who have searched for such coding have
> instead found that local changes in firing rate, not the precise
> temporal pattern of spikes, may serve as a code for environmental
> stimuli, movements, task contingiencies, etc. (e.g., Richmond's work
> on visual cortex). I know that some (e.g., Abeles) have reported that
> precise spike patterns across small ensembles of neurons can occur in
> behaving subjects, but have these patterns been shown to "be good for
> anything" with regard to the subject's performance of the task?
> Thanks in advance for any info.
> Mark Laubach
> Wake Forest University
John O'Keefe's group have shown that hippocampal place cells fire with a
very strict temporal relationship to the ongoing theta EEG rhythm in
behaving animals. Specifically, a cell will advance its firing with
respect to the theta phase as the animal runs through its place field,
always starting at the same theta phase. Thus, by knowing not just
*that* the cell was firing but also *when* it was firing with respect to
theta, it is possible to reconstruct the location of the animal much
more accurately. They have proposed a phase coding model of how an animal
might use this for navigation - I can supply some refs if you want.
k.jeffery at ucl.ac.uk
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