Differential EEG

ken kpaulc at [remove]earthlink.net
Thu Mar 18 02:01:35 EST 2004

Where has 'dinosaur' gone?


K. P. Collins

"Doktor DynaSoar" <targeting at OMCL.mil> wrote in message
news:f2tf405lbunvvibsttlm1d80l6qbvomake at 4ax.com...
> Editing some more, because, as you admit, some of it is a different
> topic.
> On Thu, 04 Mar 2004 18:22:03 GMT, "kpaulc" <kpaulc at earthlink.net>
> wrote:
> } The problem that I'm actually working
> } on in this thread is that of rendering the
> } neural Topology,
> Please explain exactly what you mean by that.
> }  graphically, by work-
> } ing back from EEG data, which is def-
> } initely doable, but which has remained
> } undone [unattempted?] - probably be-
> } cause the EEG-analysis methodologies
> } that are commonly used have been
> } handed-down from Professor to Stu-
> } dent without any Thought being given
> } to rendering data graphically - probably
> } be-cause, as 'dynasoar' has pointed-out,
> } the methodologies date back to the
> } to the Inventor of the EEG, before com-
> } puter graphics existed, and probably be-
> } cause the demands of developing Ex-
> } pertise in the previously-existing meth-
> } odology are such that they coerse the
> } Student away from thinking graphically.
> One problem you haven't confronted is the topography, and by that I
> mean sulci and gyrii, of the cortex. EEG picks up sources
> perpendicular to the surface. The less perpendicular, the less
> sensitive. Sources parallel with the surface don't get seen by the
> closest electrodes, and barely at all by distant ones which may be in
> the proper attitude.
> Seeing it all requires simultaneous MEG, which "sees" perpendicular to
> EEG. No great shakes, methodologically. It's doable.
> I can, and have, merged simultaneous EEG and MEG data, then overlayed
> that on EEG data taken simultaneous with fMRI (MRI plays hell with the
> MEG SQUIDs). The electrode placement was digitized per subject and
> placed on their anatomical MRI. The results, taken as current source
> density, were played back using the real anatomical cortical surface
> as the "screen", and presented sample by sample according to the 500
> Hz digitization rate. I tested all-pairs coherence. Had I used 3 or
> more point Laplacian, I would have done what you've described,
> imrpoved upon by use the the subject's real anatomical structure.
> Laplacian was available -- I just didn't use it.
> None of this software was written in house. It's all commercially
> available.

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