[Eeglablist] Eeg connectivity

[Scott Makeig]

This is not as simple as it might seem. After all, filtering a signal for a
desired phenomenon is always a matter of filtering out unwanted portions of
the signal. In the scalp EEG case, the projection of each cm^2 of the
cortical surface is broad - meaning that each electrode channel sums
activity from a relatively large (and non-contiguous) portion of cortex.
Thus, simply restricting the locations of the electrodes is not an
excellent way to remove activity from 'uninteresting' spatial sources -
their activities also project to the chosen scalp territory ...  However,
if you want to try that, I would suggest putting the reference electrode in
the center of the scalp array. This will make the resulting EEG
signals small (making SNR an issue), but will minimize contributions from
distant sources. Then use ICA decomposition to look for spatially separable
signals from cortical territories of interest. There is no guarantee of
success, but worth a try? ...

Scott

On Mon, Jan 11, 2021 at 2:46 PM 邓恩良 <dengenliang at icloud.com> wrote:

> I want to evaluate the dynamics of a therapy which focus  ameliorate <
> https://urldefense.com/v3/__http://www.baidu.com/link?url=2JAMESyuNrBaFj4UYhkkcSyXW50QfdMPujjbLd8DwCpg144mWDoe7LWqYXRCawNPS14V0peoJQHIOxcK9jEcnwcnHIllQP0ZGZcm24lCBDO__;!!Mih3wA!XdszptzFZDrSSLIhThtUzDNInQwBtdpnf3tcwKMh02uqngtYT-UI-rIwmIPPZzzTrrsoUg$
> > the motor cortex of stroke patients, however my eeg machine only have 18
> channels. I wander if I could attach 16 electrodes on motor cortex rather
> than the whole scalp. And if it  could work, what else should I resolve?
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-- 
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