Time frequency Analysis!

Wed Jan 31 14:03:52 CET 2007

Hello,

Thankyou for the suggestions now the timefrequency analysis works perfectly
i get better results now
Thankyou for the suggestions it was the zlim which i need to use it lower
the limits
and i also reduced the time window

I have asked questions about the other DICS analysis from Fieldtrip
i have not got any reply on that
if u can go through the previous discussion between me and Prof.Robert
I have tried using resolution to 1 Hz

A basic question, i do not have any anatomical MRI data is it useful to do
the source analysis
without it, in future i will have the MRI data

Is it possible to load the laplacian transformed data to the fieldtrip and
work on it with the
Frequency analysis, But the actual laplace transformed data is a huge file
with for ex:[151000*39] were first 35 channels are the lap.transformed EEG
channels
and the last 4 channels 36,37,38,39 are the Lap.transform EMG channels.

Is there a way to import this daten file(.mat file) to the fieldtrip and
then working on it
for the DICS analysis and then i also think then the results of the my
coherence analysis using welch periodogram method
will be comparable with the fieldtrip methods

Thanking you

With regards
M.Muthuraman.

>From: Jan Mathijs Schoffelen <Jan.Schoffelen at FCDONDERS.RU.NL>
>Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
>To: FIELDTRIP at NIC.SURFNET.NL
>Subject: Re: [FIELDTRIP] Time frequency Analysis!
>Date: Wed, 31 Jan 2007 11:21:46 +0100
>
>Dear Muthuraman,
>
>In your last mail you wrote:
> >I do get any warning while executing the singleplotTFR function
>Does this mean that you do, or do not get any warnings?
>
> >cfg.ouput='powandcsd';
>Please note that it should read cfg.ouTput (without the capital letter T)
>
>
> >cfg.baselinetype=[0.1 1.0];
>This is obviously wrong: cfg.baselinetype specifies how to do baseline
>correction. This can be 'relative' 'absolute' or 'relchange'. Please
>consult
>the help of this function, or of freqbaseline.m
>You specify the baseline-interval with cfg.baseline.
>
> >cfg.zlim=[-2e-27 2e-27];
>Your values seem to be completely clipped. Did you try around with
>different
>zlims? A typical value of 2e-27 applies to MEG, when no relative or
>relchange baselining is involved. EEG is measured in mV's, and power is
>measured in mV's-squared, so something in the order of 2e-6 seems more
>appropriate to me.
>
>Note that the nans arise when there is not sufficient data in the
>timewindow
>outside [0.25 0.75]. This of course is due to the fact that your data is
>only defined between [0 1], and your timewindow for the time-frequency
>analysis is 0.5 seconds.
>
>Yours,
>
>Jan-Mathijs
>
>
>
>
> >From: Jan Mathijs Schoffelen <Jan.Schoffelen at FCDONDERS.RU.NL>
> >Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
> >To: FIELDTRIP at NIC.SURFNET.NL
> >Subject: Re: [FIELDTRIP] Time frequency Analysis!
> >Date: Tue, 30 Jan 2007 17:34:44 +0100
> >
> >Dear Muthuraman,
> >
> >It pleases us that we finally got you to try multi-tapers for your
>spectral
> >analysis! Sometimes it's hard convincing people, but in the end...
> >
> >First of all there's a typo in your configuration for the frequency
> >analysis; this does not explain your results, but as an extra service to
> >you
> >I'd like to point it out. You specify cfg.ouput, where I guess you mean
> >cfg.output. Moreover, since you have an EMG-channel in your data, you
>might
> >be interested in computing the coherence, but therefore you have to
>specify
> >cfg.output = 'powandcsd'.
> >
> >Regarding your nans: did you check whether there are any numbers in
> >TFRmult.powspctrm. If this is the case, your problem most likely arises
>in
> >the plotting. You specify cfg.baselinetype = 'relative', but you do not
> >specify the baseline-interval. Do you get a warning when executing the
> >singleplotTFR-function?
> >If there are only nans in your TFRmult, then I don't get it, because your
> >configuration looks OK to me?
> >
> >By the way, which version of fieldtrip are you using? If you are using an
> >old one, it might be worthwile to download the latest version (there's a
> >daily update on the FTP-server, you can get there through the
> >fieldtrip-website), and try the script again (with the small changes
> >suggested).
> >
> >Yours,
> >
> >Jan-Mathijs
> >
> >
> >-----Original Message-----
> >From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On
>Behalf
> >Of Muthuraman Muthuraman
> >Sent: Tuesday, January 30, 2007 3:40 PM
> >To: FIELDTRIP at NIC.SURFNET.NL
> >Subject: [FIELDTRIP] Time frequency Analysis!
> >
> >Hello Fieldtrippers,
> >
> >I have question regarding the Time-Frequency analysis using tapers,
> >'mtmconvol' or time frequency analysis using wavelets 'wltconvol'
> >these are the parameters i use, i get all the values to be Nan's
> >Is there something wrong which i need to change in the parameters for the
> >timefrequency analysis
> >
> >hdr     = read_fcdc_header('pd_mof_tr0_c_0306.cnt');
> >emgindx = strmatch('M', hdr.label);
> >rstindx = setdiff(1:length(hdr.label),emgindx);
> >
> >trl = [];
> >trl(:,1) = [21:1000:74520-1000]';
> >trl(:,2) = [1020:1000:74520]';
> >trl(:,3) = 0;
> >
> >
> >cfg.dataset = 'pd_mof_tr0_c_0306.cnt';
> >cfg.trl     = trl;
> >cfg.channel = hdr.label(rstindx);
> >cfg.blc     = 'yes';
> >data        = preprocessing(cfg);
> >
> >cfg.channel  = hdr.label(emgindx);
> >cfg.hpfilter = 'yes';
> >cfg.hpfreq   = 10;
> >cfg.rectify  = 'yes';
> >emg          = preprocessing(cfg);
> >
> >for j = 1:length(emg.trial)
> >   emg.trial{j} = blc(emg.trial{j});
> >end
> >data         = appenddata([],data,emg);
> >
> >%---freqanalysis-mtmconvol
> >cfg=[];
> >cfg.ouput='pow';
> >cfg.sgn='data';
> >cfg.method='mtmconvol';
> >cfg.channel    = channelselection({'all' 'M1'}, data.label);
> >cfg.foi=2:2:30;
> >numfoi=length(cfg.foi);
> >cfg.t_ftimwin=zeros(1,numfoi);
> >cfg.t_ftimwin(:)=0.5;
> >cfg.tapsmofrq=zeros(1,numfoi);
> >cfg.tapsmofrq(:)=10;
> >cfg.toi=-0.5:0.05:1.0;
> >cfg.taper='dpss';
> >cfg.pad=2;
> >cfg.keeptrials='no';
> >TFRmult=freqanalysis(cfg,data);
> >
> >%---Plotting
> >cfg=[];
> >cfg.baselinetype='relative';
> >cfg.zlim=[-2e-27 2e-27];
> >cfg.showlabels='yes';
> >cfg.channel='C3';
> >singleplotTFR(cfg,TFRmult);
> >
> >
> >Thanking you
> >
> >With regards
> >M.Muthuraman.
> >
> >_________________________________________________________________
> >Tickle your funny bone with Rahul Phondke
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>h
> >tm
>
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