Modulation of Neuronal Output

Leslie Kay lmk2 at garnet.berkeley.edu
Thu Jul 7 10:50:47 EST 1994

In article <KEVIN.94Jul6184536 at jackson.head.neurology.wisc.edu>,
Kevin Hellman <kevin at jackson.head.neurology.wisc.edu> wrote:
>including piriform cortex!  Why do you singe single out the Olfactory 
>bulb?  Freeman's work was less on cognition in the olfactory bulb, but
>on epileptogensis.  

Just to clear up a misconception:  Only a portion of Freeman's work
is on epileptogenesis; it occured as a result of fiddling with parameters
in the KIII model and seeing that the thing had seizures.  He discovered
that increase in inhibition in the model or a decrease in the gain of
excitatory pathways induced seizures.  Recently work by Stripling, presented
at last year's Neuroscience meeting, has shown that seizures in rats
are produced when he stimulates the feedback pathways to the granule
cells (inhibitory) in the olfactory bulb.  There are several mysterious
drug actions which may also be explained by the "runaway inhibition" 
theory, but this is all quite speculative at this point. 

Freeman's main work is on the physiology of perception.  In fact, his
results have been confirmed now in primary visual, somatosensory, olfactory 
(pyriform), and auditory cortex of rabbits.  This was presented last year at
Neurosciences and at a couple of other conferences.  It is now being
submitted for publication (and I believe it is also in a book, but I
do not have the reference with me).

I emphasize the work _perception_, not cognition.  We really don't know
what a rat or a cat or a rabbit or even a monkey _thinks_ (or for that
matter, a human ;-) ).  We can,
however, distinguish sensory from perceptual events.  The sensory event
would be the evoked potential, and the perceptual event occurs some
200-300 msec later.  The perceptual event has to do with meaning, while
the evoked potential does not.

Leslie Kay
lmk2 at garnet.berkeley.edu

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