[FieldTrip] Running ICA on neuromag tsss data

[Peter Goodin]

Hi Fieldtrip list,

I've been using ICA (fastICA specifically) to clean blinks and cardiac artefact from my MEG data (neuromag 306 system) but find that I get some components that are "off" for a period and "on" for a period, or in other words some trials have the components "on" and others "off".

I'm assuming these "off" periods are due to the differing dimensionality within the data due to the block by block rw  nature of tsss, but when they're "on", they seem to contain a higher amplitude signal to the other components.

My questions are: Are these on / off components due the differing dimensionality between blocks due to the tsss process? Is it more likely they contain data relating to the brain, something else such as movement, a mix of the two or it's simply impossible to tell?

Thanks to anyone who can shed some light on this,

Peter

__________________________
Peter Goodin,
BSc (Hons), Ph.D Candidate.

Brain and Psychological Sciences Research Centre (BPsych)
Swinburne University,
Hawthorn, Vic, 3122

Monash Alfred Psychiatry Research Centre (MAPrc)
Level 4, 607 St Kilda Road,
Melbourne 3004
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