[Eeglablist] best approach to reject bad components when using a 256-channel (EGI)

[Isaiah Innis]

Hello Anoop Jagadeesh:


1. If you are using ICA for artifact correction purposes it is fine to
reduce the number of components. In general our labs that use ICA and 256ch
EGI do not see meaningful (ie non "mixed") components beyond the first 32
or even 24. Now if you are operating in component space there may be other
considerations. Someone in the list could hopefully advise on that.

2. These "dot" components may be indicative of bad channels or some sort of
other artifact. According to Delorme et all 2012, good components are
dipolar. (See their paper here:
https://doi.org/10.1371/journal.pone.0030135)


3. How strict you must be depends on what you are doing. If only using ICA
to remove artifacts it may only be necessary to remove a blink, eye
movement, and emg component. In your case you could ask yourself, are the
sleep spindles "noise" to you or are they activity of interest in the
experiment? Again, other eeglab users who are more familiar with ICA space
will likely have additional information.


Thank you,

-- 
Isaiah Innis
Indiana University '13
EEG Technician and MR Operator, IUB IRF
https://www.indiana.edu/~irf/home
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