[FieldTrip] artifact rejection

[qi li]

Hi Jörn,

Thanks a lot! Now it makes sense to me.

Best regards,

Qi

On Thu, Jan 5, 2012 at 3:20 AM, "Jörn M. Horschig" <
jm.horschig at donders.ru.nl> wrote:

>  Dear Qi,
>
> Though I am not sure to what z-score formula you are referring to, I guess
> you are talking about the 'summary' mode of ft_rejectvisual. Z-scores are
> computed in different ways here, once across channels and once across time,
> leading to two different plots. The third plot is an accumulated plot of
> these two, where colors indicate the strength of the selected measure (e.g.
> z-score). Thus, in terms of the z-score formula, it is once computed with
> the average and standard deviation across the time-dimension per channel
> and once across the channel-dimension per time bin. I hope this clarifies
> why the two plots don't show the same.
>
> ICA can also be applied to eye blinks, for which an example is given in
> the "Walkthrough"
>
> http://fieldtrip.fcdonders.nl/walkthrough#using_ica_for_eye_artifact_removal
>
> And of course, ICA can be used for anything else you believe in (e.g. look
> for papers by Makeig)
>
> Best,
> Jörn
>
>
> On 1/4/2012 4:52 PM, qi li wrote:
>
> Hi,
>
> I am confused about the plot of the z-score and 'most contribute' channel
> trial plot in the automatic artifact rejection tutorial. The z-score
> formula provided in the tutorial is  linear to the time course of a
> particular channel of a specific trial, but the two plots don't look alike.
>
> ICA in the tutorial only applies to ECG, can it be applied to remove eye
> blink and other known artifacts instead of rejecting trials.
>
> Thanks!
>
> Qi
>
>
>
>
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>
>
> --
> Jörn M. Horschig
> PhD Student
> Donders Institute for Brain, Cognition and Behaviour
> Centre for Cognitive Neuroimaging
> Radboud University Nijmegen
> Neuronal Oscillations Group
>
> P.O. Box 9101
> NL-6500 HB Nijmegen
> The Netherlands
>
> Contact:
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> Tel:    +31-(0)24-36-68493
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>
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