[Eeglablist] Why most of good 'brain' ICs are 'dipolar' with show 'red'-centerd scalp topos, although 2/3 of the cortex is in sulci?

[Scott Makeig]

There was an abstract presentation at a company-sponsored? session at OHBM
several years ago.  I am sure Don is still interested <dmtucker at mac.com>

Scott

On Tue, Jan 9, 2024 at 12:33 AM Евгений Машеров <emasherov at yandex.ru> wrote:

> Thank you. I would like to clarify his methodology. Perhaps it is
> described in detail somewhere? It seems to me that the frequency at which
> the impedance is measured may be significant here.
>
> Eugen Masherov
>
> > Yes, this electrical stimulation approach was attempted by Don Tucker's
> EGI
> > group for many years - with results that were not encouraging, the
> problem
> > being that almost all the injected current flows through the scalp, whose
> > local and time-varying conductivity also then has significant effect...
> The
> > SCALE approach treats the independent component signals compatible with
> an
> > effective source in cortex (having a strongly dipolar scalp projection
> with
> > equivalent dipole located in brain) as cortical stimulations, and
> > iteratively finds the (single) skull conductivity value that
> > minimizes reconstruction error of the brain sources to 'sparse, compact,
> > and smoothly' varying distribution (sometime, two bilaterally
> > near-symmetric distributions) on the imaged cortical surface - using an
> > electrical forward problem head model constructed from an individual MR
> > image - the SCS source inversion algorithm of Cao Cheng. Our next step
> > should be to build a multidimensional skull conductivity map. Again, we
> are
> > attempting to put the SCALE software on NSG (
> https://urldefense.com/v3/__http://www.nsgportal.org__;!!Mih3wA!BNS_5aZCEDYflkuo2qfpDZgsY0Z-xv87AU3QM1QiNdQklstxqDvGifU6oaUANNcbLSF18LJVuTtkYo2KIrZI$
> ) for free
> > use.
> >
> > Scott Makeig
> >
>


-- 
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott