eeg recording

Jeff Baldwin mvcs at
Sat Sep 7 00:16:12 EST 1996

kspencer at (Kevin Spencer) wrote:

>Marcus <73370.2242 at CompuServe.COM> writes:

>>How far into the cortex does a scalp electrode detect electrical 
>>activity ?  That is, what is the resistance of brain tissue, and 
>>how far does and action potential or a epsp "travel" through the 
>>brain (apart from its propagation along neural processes) ?  Any 
>>ideas ?

>To answer your question briefly, the scalp-recorded EEG at a given
>electrode site represents the temporal and spatial summation of PSPs
>from many cortical pyramidal cells.  The EEG "sources" may not all
>necessarily be in the cortex under the electrode; volume conduction
>through the brain allows sources at other [distant] locations to be
>detected at that given electrode.  A good reference on this topic is
>Paul Nunez's book, "Electric Fields of the Brain".

>Kevin Spencer
>Cognitive Psychophysiology Laboratory and Beckman Institute
>University of Illinois at Urbana-Champaign
>kspencer at

I haven't the time necessary to spend obtaining and reading the book,
but I _AM_ interested: Why just the pyramidal cells. They aren't the
only ones with activity.... why is EEG from only those (or primarily
those) cell types?
Jeffrey L. Baldwin, Mind & Vision Computer Systems
"Intelligent Processing Systems for the Energy Industry"
Voice/Fax/Data: (713) 550-4534     email: mvcs at

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