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--></style></head><body lang=FR link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Dear EEGLAB Community,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m trying to study the ERD/ERS (event related spectral pertubations) of multiple subjects in different conditions (multiple trials, epochs [-4000 1000], Fs=1000 Hz, Notch filtered) but I have some questions and I can’t find answers despite many questions asked on the list about this subject…<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My questions (and solutions so far…) are : <o:p></o:p></p><p class=MsoNormal><b>1 – How to extract ERSP according to Pfurscheller </b><i><o:p></o:p></i></p><p class=MsoNormal>So far I did this : <o:p></o:p></p><p class=MsoNormal> >> [STUDY ALLEEG] = std_precomp(STUDY, ALLEEG, {}, 'interp', 'on', 'recompute', 'on', 'ersp', 'on', 'erspparams', {'cycles' [7 0.1] 'freqs' [7 23] 'ntimesout' 388 'freqscale' 'linear' 'padratio' 4 'baseline' [-3000 -2000]}); %% Compute ERSP with a baseline set between -3sec & -2sec<o:p></o:p></p><p class=MsoNormal> >> STUDY = pop_erspparams(STUDY, 'condstats', 'on','freqrange',[]); <o:p></o:p></p><p class=MsoNormal> >>[ STUDY erspdata ersptimes erspfreqs pgroup pcond pinter] = std_erspplot(STUDY,ALLEEG,'plotfunc','newtimef','timerange', [],'trialbase', 'on','freqrange', [], 'channels', {'C1';'CZ';'C2';’etc….’}) <o:p></o:p></p><p class=MsoNormal> >> ersp=erspdata{:,:,:,:}; %% change erspdata (cell) to double<o:p></o:p></p><p class=MsoNormal> >> ersp2=(10.^(ersp/10)-1)*100; %% Pfurscheller’s formula of ERSP in percentage <i>and not</i> <i>ERSP=10*log10(A/R) (which is the format of values given by time frequency decomposition ? ) </i><span style='font-family:Wingdings'>à</span> Is it correct? I found it on this post : <a href="https://sccn.ucsd.edu/pipermail/eeglablist/2012/004755.html">https://sccn.ucsd.edu/pipermail/eeglablist/2012/004755.html</a><i> <o:p></o:p></i></p><p class=MsoNormal><i><o:p> </o:p></i></p><p class=MsoNormal>Is this method good to extract ERSP in percentage (with 0% the value at Baseline) ? Is it the format of values in the variable ‘ersp2’ ? I’m a bit lost between log, linear and std format of the data given by the time-frequency decomposition in EEGLAB Study design….<o:p></o:p></p><p class=MsoNormal>There is an other post about that : <a href="https://sccn.ucsd.edu/pipermail/eeglablist/2013/006061.html">https://sccn.ucsd.edu/pipermail/eeglablist/2013/006061.html</a>. I’m not sure what is the format of the data (standard deviation of log-transformation ?)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> >> S1ersp=ersp(:,:,:,1); %%extract data for S1<o:p></o:p></p><p class=MsoNormal> >> S2ersp=ersp(:,:,:,2); %% extract data for S2<o:p></o:p></p><p class=MsoNormal> >> idxfreqalpha=find(erspfreqs>=7 & erspfreqs <= 13); % alpha band between 7-13 Hz<o:p></o:p></p><p class=MsoNormal> >> idxfreqbeta=find(erspfreqs>=16 & erspfreqs <= 21); <o:p></o:p></p><p class=MsoNormal> >> idxtime=find(ersptimes >= -2000 & ersptimes <=400); %% Analyze ersp between -2 seconds and +400ms<o:p></o:p></p><p class=MsoNormal> >> timex=ersptimes(ersptimes>= -2000 & ersptimes<=400); <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal><b>2- Is there a faster way (or better) to Compute ERD (percent change) ? <o:p></o:p></b></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b>3-Is it possible to use the statcond() function to do this kind of statistical analysis : Compare ERSP between 2 differents conditions of multiple subjects for each channel</b> ? What is the format of data given in the workspace ?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b>4 - Is it ok to do a wavelet transform [7 0.1] for frequencies between [7-23] ?</b> Because I lost the first second (-4000 to -3000ms) doing this kind of wavelet transform.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sorry for all these questions at the same time but if anyone could give me some leads I would really appreciate because I don’t know if i’m doing right …<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sincerely,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Benjamin, <span style='font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Courier New"'><o:p> </o:p></span></p></div></body></html>