freqanalysis & cfg.channel

[Akiko Ikkai]

Hi,

I'm trying to run TFR on MEG data and plot the results, and getting puzzling figures.

Both freqanalysis and multiplotTFR run fine, and figures are produced, but the first channel (first channel in ft_data.label) is always extremely noisy (barely changing from the baseline, but showing random patches of activations across time and freq). When I take out that channel with

cfg.channel = {'all','-1'}; % when the first channel is noisy

the second channel (now the first in label) shows the same trend, if I take out the second, the third one is bad, etc... Other channels don't seem to be affected.

I'm pasting my code during this process below. Can anyone tell me what might be going wrong, and when the best point to delete bad channels?

Thanks in advance, Akiko

%%% to run freq analysis %%%
cfg.output       = 'pow';

cfg.method       = 'mtmconvol';
cfg.taper        = 'hanning';
cfg.foi          = 4:2:50;
cfg.t_ftimwin    = ones(length(cfg.foi),1).*0.5;
cfg.toi          = -.5:0.05:2;
cfg.channel = {'all','-1'}; % when the first channel is noisy

TFRhann_Rvalid = freqanalysis(cfg, Rvalid);

cfg = [];
cfg.baseline     = [-.1 0];
cfg.baselinetype = 'relative'; 	
cfg.xlim = [-0.1 1.2];
cfg.showlabels   = 'yes';	
cfg.colorbar = 'yes';

figure(1);clf
cfg.ylim = [5 50];
cfg.zlim = [0 2];
multiplotTFR(cfg, TFRhann_Rvalid); % after importing channel layout

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