ICA after megrealign

[Giovanni Piantoni]

dear Fieldtrip users,

I am trying to run an ICA decomposition on some MEG/CTF data (normal
infomax runica.m algorithm). The ICA is generally successful (there
are components that have a clear dipole scalp projection).
As I am using ICA not only for artifact rejection but also for data
analysis, I'd like to realign the data first.
However, if I try to run ICA after megrealign (cfg.pruning = 0, to
avoid rank-deficient data), the topoplots of the components look weird
(the same topoplot for all the components with only one electrode
active or with a strong activation on the edges). I tried to change
some parameters in megrealign and componentanalysis but with little
improvement.

Is there any theoretical limitation on running ICA after realignment?
Has anybody tried megrealign + ICA with more success?

Thanks,

Giovanni

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Giovanni Piantoni, Ph.D. student
Dept. Sleep & Cognition
Netherlands Institute for Neuroscience
Meibergdreef 47
1105 BA Amsterdam (NL)

+31 (0)20 5665492
g.piantoni at nin.knaw.nl
www.nin.knaw.nl/research_teams/van_someren_group

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