[FieldTrip] problem with surface Laplacian

[Hwee Ling Lee]

Hi,

Would it possible to change the number of channels in the sensor
description? There are some channels that I cannot repair, hence, I decided
to discard them completely from the analyses.

Cheers,
Hweeling


On 17 December 2014 at 15:07, Max Cantor <mcantor at umich.edu> wrote:
>
> It seems like the issue is between the number of channels in your input
> (48) is different from the number of channels in the sensor description
> (60). You should use ft_channelrepair to interpolate the removed channels,
> and then it should work barring any other issues.
>
> On Wed, Dec 17, 2014 at 5:45 AM, Hwee Ling Lee <hweeling.lee at gmail.com>
> wrote:
>
>> Dear all,
>>
>> I have 60 channel EEG resting state data, and after discarding bad
>> channels, I am left with 48 channels common to all subjects.
>>
>> I applied scalp current density to my data before extracting power
>> information from my EEG data. The EEG cap that I used was in a 10-10
>> system, and I don't have the electrode position file. Hence, I used the
>> default electrode position file named 'standard_1005.elc' for the purpose.
>>
>> Here's the part of my script for the surface Laplacian:
>>
>>
>>     cfg_neighb.method = 'template';
>>     cfg_neighb.layout = 'EEG1010.lay';
>>     cfg_neighb.channel = 'all';
>>     cfg_neighb.feedback = 'no';
>>
>>     neighbours = ft_prepare_neighbours(cfg_neighb, data7);
>>
>>     cfg                 = [];
>>     cfg.method          = 'finite';
>>     cfg.elecfile        = 'standard_1005.elc';
>>     cfg.elec            = ft_read_sens(cfg.elecfile);
>>     cfg.trials          = 'all';
>>     cfg.neighbours      = neighbours;
>>     cfg.conductivity    = 0.33;
>>
>>     data8               = ft_scalpcurrentdensity(cfg, data7);
>>
>> When I tried to extract power from data8 (after surface Laplacian), I
>> keep getting an error message (see below). I'm not sure why this would be
>> the case, and would appreciate very much if someone could help me resolve
>> the error!
>>
>> Thank you!
>>
>> Here's my script for extracting the power:
>>  cfg                 = [];
>>     cfg.output          = 'pow';
>>     cfg.channel         = {'all'};
>>     cfg.method          = 'mtmfft';
>>     cfg.keeptrials      = 'no';
>>     cfg.tapsmofrq       = 5;
>>     cfg.layout          = 'EEG1010.lay';
>>
>>     % for frequencies up to 30 Hz
>>     cfg.foilim          = [1 30]; % either the full range of frequencies
>> (data2.hdr.Fs/2) or up to 100 Hz
>>     cfg.taper           = 'hanning';
>>
>>     % find the index for the c200 condition
>>     pre_c200_idx = find(data8.trialinfo == 200);
>>     cfg.trials          = pre_c200_idx;
>>     LF_pre_c200        = ft_freqanalysis(cfg, data8);
>>
>> Here's the output plus error message:
>>
>> the input is raw data with 48 channels and 343 trials
>> Error using ft_datatype_sens (line 375)
>> inconsistent number of channels in sensor description
>>
>> Error in ft_datatype_raw (line 138)
>>       data.elec = ft_datatype_sens(data.elec);
>>
>> Error in ft_checkdata (line 223)
>>   data = ft_datatype_raw(data, 'hassampleinfo', hassampleinfo);
>>
>> Error in ft_freqanalysis (line 209)
>> data = ft_checkdata(data, 'datatype', {'raw', 'raw+comp', 'mvar'},
>> 'feedback',
>> cfg.feedback, 'hassampleinfo', 'yes');
>>
>> Best regards,
>> Hweeling
>>
>>
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>
>
>
> --
> Max Cantor
> Lab Manager
> Computational Neurolinguistics Lab
> University of Michigan
>


-- 
=================================================
Dr. rer. nat. Lee, Hwee Ling
Postdoc
German Center for Neurodegenerative Diseases (DZNE) Bonn

Email 1: hwee-ling.lee<at>dzne.de
Email 2: hweeling.lee<at>gmail.com

https://sites.google.com/site/hweelinglee/home

Correspondence Address:
Ernst-Robert-Curtius Strasse 12, 53117, Bonn, Germany
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