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Non-hippocampal theta: mechanisms?

F. Frank LeFever flefever at ix.netcom.com
Thu Apr 15 22:06:41 EST 1999


Matt Jones, in a recent comment, cited some temporal parameters of GABA
activity in the hippocampus which neatly fit the requirements for
hippocampal theta, but he was quick to point out to me that this did
not mean it was necessarily the ONLY basis for it, and cited a few more
cellular-level processes which might also be considered (sorry, Matt,
if I summarize you imprecisely).

The more I read about hippocampal theta (and perhaps thalamic
oscillations in this range), the more it seems to me that (1) extrinsic
factors may be fundamental (septal input for hippocampus; pontine for
thalamus?), and (2) other kinds of theta, especially those associated
with focal or diffuse pathologies, may be based on quite different
mechanisms.

I haven't been able to find relevant work in recent literature, but
maybe it is to be found in older lit (an editorial in J. Clin.
Neurophysiol last year pointed out that there has been a dearth of
really fundamental EEG research in the past 20 years).

Will be grateful for any references or ideas about cellular basis of
diffuse or focal slowing, "theta bursts" or "paroxysmal slowing".

n.b.: looking for CELLULAR basis--not looking for conditions in which
they occur, unless you think you know of some I haven't heard of yet
(already know about it in Alzheimers, ADD, stroke, hepatic
encephalopathy, etc.)...

However: although I already know about it in mild head injury, would
welcome any citations I may have missed; also any I may have missed re
infecttion, inflammation, etc.

F. Frank LeFever, Ph.D.
New York Neuropsychology Group



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