[Eeglablist] CSD maps in STUDY design

[Marco Montalto]

Thanks for the information Arno! So if I understood you correctly what I can do is prepare the data (CSD transform the data) using, for example, the CSD toolbox. Then I import into EEGLAB and create a study with the CSD transformed datasets. And then the resulting maps generated after precomputing measures for power spectra will be equivalent to CSD maps. Is this correct?

Regards,
Marco

On 20 Jan 2013, at 22:04, Arnaud Delorme <arno at ucsd.edu> wrote:

> Dear Marco,
> 
> it seems that for power spectrum, although you can compute the laplacian of the spectrum power maps, it does not correspond to the CSD (since spectral decomposition are not linear). Juggen pointed that out in email to the list.
> 
> Rigth now, your only option is to compute CSD on all datasets then build a STUDY, and compute the spectrum.
> 
> Best,
> 
> Arno
> 
> On 20 Jan 2013, at 05:37, Marco Montalto wrote:
> 
>> Dear Arno,
>> 
>> I have tried the code you have so kindly provided me with but every time I use it MATLAB freezes and I have to quit the program.
>> 
>> I am inputting the code in the following manner:
>> 
>> mergelocs = eeg_mergelocs(ALLEEG.chanlocs);
>> [STUDY spec ] = std_specplot(STUDY,ALLEEG,'channels', { mergelocs.labels }, 'topofreq', [8 12]);
>> for cond = 1:3
>> 	spec_cond = spec{cond}
>> TMP = EEG(1);
>> TMP.chanlocs = mergelocs;
>> TMP.data = squeeze(spec{1});
>> CSD = eeg_laplac(TMP, 1);
>> average_CSD = mean(CSD,2); 
>> figure; topoplot(average_CSD, mergelocs);
>> 
>> Would you by any chance know what I am doing wrong?
>> 
>> Thanks and regards,
>> Marco
>> 
>> On 20 Jan 2013, at 07:07, Arnaud Delorme <arno at ucsd.edu> wrote:
>> 
>>> Dear Marco,
>>> 
>>> yes, this code is actually for power spectrum. 
>>> For 3 conditions, loop on each condition
>>> 
>>> for cond = 1:3
>>> 	spec_cond = spec{cond}
>>> 	... % compute CSD and plot
>>> end;
>>> 
>>> Best,
>>> 
>>> Arno
>>> 
>>> On 19 Jan 2013, at 03:07, Marco Montalto wrote:
>>> 
>>>> Dear Arno,
>>>> 
>>>> Thank you for your reply and for all the information you have supplied me with. I just have two questions:
>>>> 
>>>> 1) Can I use this code if I precompute measures in STUDY design for power spectrum?
>>>> 
>>>> 2) I have three conditions in STUDY design. How do I produce CSD maps for each condition?
>>>> 
>>>> Thanks once again and looking forward to your reply.
>>>> 
>>>> Regards,
>>>> Marco
>>>> 
>>>> On 19 Jan 2013, at 02:59, Arnaud Delorme <arno at ucsd.edu> wrote:
>>>> 
>>>>> Dear Marco,
>>>>> 
>>>>> based on another email I sent earlier to the list.
>>>>> 
>>>>> % merge all channel location structures for the STUDY
>>>>> mergelocs = eeg_mergelocs(ALLEEG.chanlocs);
>>>>>  
>>>>> % get ERSP results (scalp maps) - for example scalp topography of spectrum in the alpha band
>>>>> [STUDY spec ] = std_specplot(STUDY,ALLEEG,'channels', { mergelocs.labels }, 'topofreq', [8 12]);
>>>>> 
>>>>> then you may use one of the many laplacian function eeg_laplac.m is a good one although you will have to rebuild a dataset to use it. Something like
>>>>> 
>>>>> TMP = EEG(1);
>>>>> TMP.chanlocs = mergelocs;
>>>>> TMP.data = squeeze(spec{1});
>>>>> CSD = eeg_laplac(TMP, 1);
>>>>> 
>>>>> % plot average CSD scalp topography
>>>>> average_CSD = mean(CSD,2); % average across subjects
>>>>> figure; topoplot(average_CSD, mergelocs);
>>>>> 
>>>>> Best,
>>>>> 
>>>>> Arno
>>>>> 
>>>>> <Screen Shot 2013-01-18 at 17.58.30.png>
>>>>> 
>>>>> On 17 Jan 2013, at 13:56, Marco Montalto wrote:
>>>>> 
>>>>>> Dear List,
>>>>>> 
>>>>>> Is there a way of producing CSD (current source density) maps in EEGLAB, in a STUDY design?
>>>>>> 
>>>>>> Marco Montalto
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>>>>> 
>>>> 
>>> 
>> 
> 

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