[Eeglablist] Interpolation and ICA Update?

[Tarik S Bel-Bahar]

Leave questionable electrodes out before ica.
If you have a sparse electrodes array, dont be draconian. some of my best
decompositions come with discounting up to 40% sometimes, although I prefer
not to remove more than 25% or so.

Interpolate if you must after ICA.
After decomposition, Normal ic analyses should not require interpolation,
unless you need equivalent scalp maps across ICs, or you are backprojecting
to scalp/erp land.

You could run a second Ica yourself, after interpolation, to see what
happens to extant IC s
in a new, second decomposition.

Please try  be sure to feed your final conclusions back to the list.
 On Feb 18, 2012 12:50 PM, "Matthew Stief" <ms2272 at cornell.edu> wrote:

> Greetings!
>
> I was wondering if anyone could weigh in on some (as far as I can tell)
> outstanding issues in how to optimally deal with removed channels before
> ICA.
>
> The remaining question seems to me to be this: is it superior to A)
> interpolate the removed channels, run PCA to appropriately reduce the
> dimensionality of the data, and then run ICA, or B) simply leave the
> electrodes out and interpolate after running ICA.
>
> With the fact in mind that both the interpolation and the PCA introduce
> non-linearities into the data, is it the case that the addition of the new
> "clean" interpolated channels provides additional data deriving from neural
> sources for the ICA to work with, or does the fact that it's just a
> combination of data from other electrodes negate this possibility?  The
> negative to the interpolation/PCA approach is clear, and may not be very
> substantial, but is there evidence for any positive at all?
>
> --
> _________________________________________________________________
> Matthew Stief
> Human Development | Sex & Gender Lab | Cornell University
> http://www.human.cornell.edu/HD/sexgender
>
>
> Heterosexuality isn't normal, it's just common.
> -Dorothy Parker
>
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