AW: [Eeglablist] alpha like noise

Julie Onton julie at sccn.ucsd.edu
Wed Oct 19 11:43:33 PDT 2005


Yes, I agree. This looks like normal (and good!) data to me.

Julie

-- 
Julie Onton, PhD
Swartz Center for Computational Neuroscience
Institute for Neural Computation
University of California, San Diego
(858) 458-1927 ext 17

> Hi Maarten,
> You are probably looking at real data, leave it in.
> There are several reports of cognitive alpha processes,
> for example in expectancy and also working memory.
> See some references below.
> Best,
> Johannes
>
> Petsche H, Kaplan S, von Stein A, Filz O.
> The possible meaning of the upper and lower alpha frequency ranges for cognitive and creative
> tasks.
> Int J Psychophysiol. 1997 Jun;26(1-3):77-97.
>
> Von Stein et al.
> http://www.pnas.org/cgi/content/full/97/26/14748
>
> von Stein A, Sarnthein J.
> Different frequencies for different scales of cortical integration: from local gamma to long range
> alpha/theta synchronization.
> Int J Psychophysiol. 2000 Dec 1;38(3):301-13
>
> Jensen et al
> http://cercor.oxfordjournals.org/cgi/content/full/12/8/877
>
> Klimesch Group
>
> Basar Schurmann Group
>
> and some others
>
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: eeglablist-bounces at sccn.ucsd.edu [mailto:eeglablist-bounces at sccn.ucsd.edu] Im Auftrag von
> Maarten Mennes
> Gesendet: Dienstag, 18. Oktober 2005 11:32
> An: eeglablist at sccn.ucsd.edu
> Betreff: [Eeglablist] alpha like noise
>
> Dear all,
>
> During some of the tasks we used in our lab we encountered a sort of alpha-wave-like noise in our
> EEG-data (see figures in attachment).
> However, subjects were fully awake and had their eyes opened.
>
> This alpha-noise was sometimes stimulus locked as in the attached figure, however, most of the
> time present in clear bursts. In addition this noise was not always limited to the posterior
> channels where you would expect the true alpha waves.
>
> We did try a number of techniques in order to filter this noise out, but did not succeed. ICA for
> example could not confine this noise to one component.
>
> Has anyone else on this group encounterd this kind of noise in your data and if so, what did you
> do in order to prevent or filter out these wave-patterns?
>
> Would using more electrodes than the current 19 enable ICA to isolate this noise in more confined
> components?
>
> yours sincerely,
> Maarten Mennes
>
> ------------------------------
> Maarten Mennes
> Ph.D. Student
> Laboratory for Neuropsychology
> Department of Pediatrics
> UZ Gasthuisberg, O&N
> Herestraat 49
> 3000 Leuven
> Belgium
>
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