ICA on 275ch MEG... removing artifacts

[Suresh Muthukumaraswamy]

Hi Everybody,
     I have started playing with the componentanalysis and rejectcomponent
functions to try to remove eye artefacts from CTF 275 channel MEG data. The
aim is to try to remove eye artefacts and then run SAM analyses.
Technically, I have the approach working fine and it does seem to reduce the
eye artefact in the MEG channels near the front of the helmet (I have EOG
traces as well)
Specifically I was wondering

  Typically how many components do people normally estimate and then how
many of these would normally get rejected as containing eye artefact? 270
components is alot to look through! I see one can limit the number of
components the function can return....

 Do people normally reject solely on topography or do they do a frequency
analysis of the component time-course or perhaps other things?

Moreoever, I was also wondering if anyone had carried out any kind of
systematic comparison between this approach for MEG compared to traditional
EEG approaches to this problem (e.g. projecting out the EOG channels)?

Thanks in advance

  Suresh

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