[Eeglablist] eeglablist Digest, Vol 47, Issue 1
Murugappan M
m.murugappan at gmail.com
Mon Sep 8 20:57:16 PDT 2008
Dear all,
I have my own data set for emotion recognition using EEG signals. In my data
acquistion system, i have followed to extract the data in "Average-64"
method.
I also have an option to select "Current Montage" data.
1. Now my doubt is what is the difference between "Average- 64" and Current
Montage. Which one is effcetive one for analysing the EEG signal.
2. I am used Butterworth filtering and Average Mean Reference method for
removing
the noises and artifacts.Will it be enough for removing noises and
artifacts effectively?
3. I started my experiment once i confirmed the Impedance of all eelctrodes
will come
below the thresold value (> 10 Kilo Ohm). However, when the subject move
some
have in randam manner during my experiment means, i faced to have some
electrodes
which is haveing the impedance above the thresold value. Is there any
significance of
this impedance variation in EEG signals for getting an effective one ?
4. For my experiment, What is the number of minimum subjects is required to
validate
my results. Some of them are telling that, 100 0r 200 subjects. But its
quite impossible
for me. According to the universal statistics, what is minimum no of
subjects required
to validate the results?
Pl kindly reply to my quires. Hope my questions not only benifit for myself
also for others.
Thanks in advance.
M Murugappan.
2008/9/7 <eeglablist-request at sccn.ucsd.edu>
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> Today's Topics:
>
> 1. FFT in EEG signal (Mohd Naz)
> 2. advice on exporting to cartool (Hamish Innes-Brown)
> 3. Re: FFT in EEG signal (arno delorme)
> 4. What would be the best way to determine dipole locations for
> P300 responses? (Fuh-Cherng Jeng)
> 5. Re: EEGLAB&FastICA (Arnaud Delorme)
>
>
> ---------- Forwarded message ----------
> From: Mohd Naz <starz_naz at yahoo.com>
> To: eeglablist at sccn.ucsd.edu
> Date: Sun, 31 Aug 2008 12:05:35 +0800 (SGT)
> Subject: [Eeglablist] FFT in EEG signal
> if i want to know frequency content in eeg signal recorded for 30
> minutes, could i make use FFT?
>
> ------------------------------
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>
> ---------- Forwarded message ----------
> From: Hamish Innes-Brown <hinnesbrown at gmail.com>
> To: EEGLab List <eeglablist at sccn.ucsd.edu>
> Date: Wed, 3 Sep 2008 17:36:39 +1000
> Subject: [Eeglablist] advice on exporting to cartool
> Hi there, I'm writing to the list to see if anyone has any advice on how
> best to export data from EEGLAB to Cartool...
> http://brainmapping.unige.ch/Cartool.htm
>
> I have the data in a variety of forms in EEGLAB - continuous, epoched and
> averaged. The best thing (I think) would be to export the continuous data
> in a format that Cartool can read, preferably a format that contains all the
> event onformation as well, like neuroscan .EEG (this is just one I know) or
> EDF.
>
> I looked into it a bit, and discovered the Biosig toolbox distributed with
> EEGlab can read and write EDF, using the "ssave()" command.
>
> help ssave
> SSAVE saves signal data in various data formats
>
> Currently are the following data formats supported:
> EDF, BDF, GDF, BKR, SND/AU, (WAV, AIF)
> and WSCORE event file
>
> HDR = ssave(HDR,data);
> HDR = ssave(FILENAME,data,TYPE,Fs);
>
> FILENAME name of file
> data signal data, each column is a channel
> TYPE determines dataformat
> Fs sampling rate
>
> see also: ssave, sopen, swrite, sclose, doc/README
>
>
>
> Horay! But am I right in thinking this command will simply accept a matrix
> with rows=samples... And no provision for events or epochs? So I would
> have to firstly elect data by each stimulus type, and then export a version
> of [EEG.data] where all the epochs in the 3rd dimension were concatenated
> together, and then hope that there is some way to re-segment in cartool...
>
> Then I searched my archives of eeglablist emails for a dim memory - the
> writecnt function. This looks like it might do the trick, except that my
> data are already epoched, and there is no equivalent "writeeeg" to write a
> neuroscan epoched *.eeg file...
>
> Any tips - has anyone opened ICA-filtered epochs from EEGLAB in Cartool
> before?
>
> Thanks!
>
>
>
> -hamish0
>
>
>
>
> ---------- Forwarded message ----------
> From: arno delorme <arno at ucsd.edu>
> To: starz_naz at yahoo.com
> Date: Fri, 5 Sep 2008 14:51:31 -0700
> Subject: Re: [Eeglablist] FFT in EEG signal
> Dear Starz,
>
> If X is the data, nfft the size of the FFT window and srate the sampling
> rate. The formula below will do all channels at once if they are in the
> first dimension.
>
> tmp = fft(X, nfft, 2);
> f = linspace(0, srate/2, size(tmp,2)/2);
> f = f(2:end); % remove DC (match the output of PSD)
> tmp = tmp(:,2:size(tmp,2)/2,:); % the FFT decomposition is
> symmetrical
> res = 10*log10(mean(abs(tmp).^2,3));
> figure; plot(f, res);
>
> best,
>
> Arno
>
>
>
> ---------- Forwarded message ----------
> From: Fuh-Cherng Jeng <jeng at ohio.edu>
> To: eeglablist at sccn.ucsd.edu
> Date: Tue, 05 Aug 2008 17:45:49 -0400
> Subject: [Eeglablist] What would be the best way to determine dipole
> locations for P300 responses?
> Dear all,
>
> I have recorded P300 responses using a 64-channel cap in two groups of
> participants and found that the P300 latencies in group A is significantly
> longer than those in group B. As a follow-up of this finding, I would like
> to do some dipole fitting and see if the P300 dipole locations are
> significantly different between the two groups. I have two methods in mind,
> but am not sure which method would be making any sense at all. sense than
> the other in terms of finding the dipole locations for P300 responses.
>
> (1) use dipfit_erpeeg() to fit the ERP topography at the time point where
> the P300 latency is determined by the experimenter.
>
> (2) do ICA first and use multifit() to do a dipole fitting on a specific
> ICA component that correspond the best to the P300 responses.
>
>
> If anyone could help me with this or simply tell me a better way of finding
> the P300 dipole locations, I would greatly appreciate it.
>
> Sincerely,
>
> Fuh
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Arnaud Delorme <arno at sccn.ucsd.edu>
> To: stllagialla at yahoo.it
> Date: Fri, 5 Sep 2008 16:22:22 -0700
> Subject: Re: [Eeglablist] EEGLAB&FastICA
> Dear Stela,
>
> I retested fastica below and it works like a charm for me. Be sure to use
> the latest EEGLAB version available on the web.
> Best,
>
> Arno
>
> On 12 août 08, at 04:45, stella gialla wrote:
>
> Dear All
> I have a problem with fastica toolbox.
> I read on the eeglab tutorial that if I want to use fastica algorithm in
> ICA tool I have to download the fastica package and to set the path on
> matlab.
> I did so but when I started ICA tool an error has shown:
> "ERROR EEGLAB:
> error using ==> whitenv
> too many input arguments."
> but I did not do anythingelse written on the eeglab tutorial (ref. KEY STEP
> 9:CALCULATE ICA COMPONENTS). I did not insert any commandline options and my
> data reply what it is reported in the "very important note".
> what do I have to do?
> thank you
> kind regards
> Stella
>
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--
Thanks & Regards,
======================================
M.MURUGAPPAN,
Ph.D Scholar, School of Mechatronics Engineering,
Universiti Malaysia Perlis (UniMAP),
02600, Jejawi, Arau, Kangar,
Perlis, Malaysia.
Phone : (006)-017-4064707
E-mail: m.murugappan at gmail.com
======================================
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