[Eeglablist] search for spike
smakeig at ucsd.edu
Tue Mar 9 16:16:51 PST 2004
What is your experience in working with ICA components that explain
spikes? In this case, you would not need to choose a portion of the
spike to fit - that is, ICA would suggest a solution to this problem.
Camilo José Borrego Abello wrote:
> Hi Arno and Jeff:
> Thanks for your mail.You are quite right. The best is
> to use menu Plot>component ERP>with scalp component
> maps. The first component in the top line of the
> window was found around the same location for the 3
> epoch lenght used by dipfit.
> The current opinion ( Scherg, Ebersole group´s,
> Lantz-see J. Clin. Neurophysiol. 20(5):311-319,2003)
> is to work with the rise part of the spike. Certainly
> Gotman group´S is not very clear at this matter. They
> use segments lenght of 320 ms and 640 ms (see
> Kobayashi et al, Clin. Neurophysiol. 112(2001):
> 405-413 page 407),or increasing the number of spikes,
> the "density", minimizing the background of EEG
> without success. In the last case they said that it
> was because of the kurtosis is affected, as spikes
> became small and not peaky, but this may not be true
> because the kurtosis is in reality not affected, it is
> just a scale adjustement in the printed drawing.
> That was the reason behind our question of the ideal
> lenght for a good ICA decomposition in
> epilepsy.Increasing the number of channels perhaps is
> not the complete solution.
> This is a warning for people who work on this area
> with DIPFIT as it is possible to miss the right
> location, until a reasonable length is found. The
> ideal epoch length remain to be determined.
> Best regards,
> Camilo Borrego
> Universidad de Antioquia
> Medellin, Colombia
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