problems with DICS

[Nathan Weisz]

hi,

i'm not sure whether the following question is a fieldtrip-related
question or a rather general question.

we use a 148 sensor BTI system.
since a couple of days we're struggling with a data-set in which we'd
like to localize auditory cortical alpha desynchronizations. on a
sensor level they are clearly observable (see attached Pitcure 2).
however when running DICS it seems like the brain is more or less
increasing power post-stimulus.
what makes me wonder is that it's exactly the same script (i could
provide more details of course) which worked very successfully
previously. our notion was initially that something is weird with the
leadfield. but -illegally- testing it with a leadfield from another
subject where things worked out basically gave more or less the same
picture. now we assume that something is fishy with the data itself,
that is not clearly observable when looking at the data on a trial-by-
trial basis, leading to bad spatial filters. any suggestions how this
could be diagnosed?

are there any other suggestions? or has anybody had similar problems
lately?

cheers,
n









--------------------------------------------
Dr. Nathan Weisz

OBOB-Lab
University of Konstanz
Department of Psychology
P.O. Box D23
78457 Konstanz
Germany

Tel: ++49 - (0)7531 - 88 45 84
Email: nathan.weisz at uni-konstanz.de
Homepage: http://www.uni-konstanz.de/obob

"Nothing shocks me. I'm a scientist." (Indiana Jones)


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