[FieldTrip] Question regarding coherence statistics

Hwee Ling Lee hweeling.lee at gmail.com
Wed Aug 13 10:43:22 CEST 2014


Dear all,

I refer to a previous post regarding 'question about coherenece statistics
for group analysis related to J. Neuroscience 2011 and Science 2005 (both
papers by Jan-Mathijs Schoffelen).

I tried to follow the suggestions regarding the comparison of coherence for
two conditions.

This is what I set up for my case:

cfg = [];
cfg.keeptrials = 'no';
cfg.channel = {'all'}; (there are 60 EEG channels in this case).
cfg.channelcmb = {cfg.channel, cfg.channel};

freq1 = ft_connectivityanalysis(cfg, cond1); %this is done for 5 subjects
separately
freq2 = ft_connectivityanalysis(cfg, cond2); %this is done for 5 subjects
separately

freq1 = atanh(freq1.cohspctrm) - atanh(freq2.cohspctrm); %this is done for
5 subjects separately
freq2.cohspctrm(:) = 0; %this is done for 5 subjects separately

cfg = [];
cfg.layout = 'EEG1010.lay';
cfg.latency = 'all';
cfg.avgovertime = 'no';
cfg.parameter = 'cohspctrm';
cfg.method = 'montecarlo';
cfg.statistic = 'diff';
cfg.tail = 0;
cfg.alpha = 0.05;
cfg.numrandomization = 10000;
cfg.ivar = 2;
cfg.uvar = 1;

% design matrices
clear design;
design(1,:) = [1:5, 1:5];
design(2,:) = [ones(1,5), ones(1,5) * 2];
cfg.design = design;

cfg.avgoverfreq = 'yes';
cfg.frequency = [2 4]; % this will be performed for different frequency
bands
[prec200_delta_stat] = ft_freqstatistics(cfg,
sub01_freq1, sub02_freq1,  sub03_freq1,  sub04_freq1,  sub05_freq1,
sub01_freq2, sub02_freq2,  sub03_freq2,  sub04_freq2,  sub05_freq2);

However, when I tried to run this script, I get an error message:

Reference to non-existent field 'label'.

Error in ft_freqstatistics (line 131)
  haschan(i)  = ~isempty(strfind(varargin{i}.dimord, 'chan')) ...

Can someone please help?

Thanks!

Cheers,
Hweeling
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