[Eeglablist] Topographic plot question
koutras at giapi.wcl2.ee.upatras.gr
Wed Jan 25 08:18:57 PST 2006
I'm interested in plotting the topographic map of a set of specific
independent components that ICA has found on some EEG recordings. The
number of EEG electrodes is 64. However the problem I face, is that the
only data that I have, is a subset of N independent components where
N<number of electrodes together with the N vectors of the ICA weights (W
has dimension of Nx64) and the channel locations.
Would it be possible to perform such a thing? I know that classical ICA
results in a separating SQUARE matrix 64x64, the inverse of which is
used by topoplot (the columns of A=inv(W) to be more specific).
In my case however the separating matrix W is rectangular and no matrix
inversion can be performed. Can the pseudo-inverse of W be used without
error? Would this work for the case of say only one independent component?
Has anyone faced the same problem?
Thanks in advance,
Athanasios Koutras, PhD
Electrical & Computer Engineer
University of Patras
26100 Patras, Hellas
Tel: (+30)2610 969116
e-mail: koutras at giapi.wcl2.ee.upatras.gr
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