[FieldTrip] Cluster based permutation plot

[Luca Moretti]

Dear all,

I am having some problems with plotting the results of a cluster based permutation test.

I am running a within subjects’ experiment with 8 conditions combined in a 2X2X2 design. Theta and Alpha power are used as dependent variables. I would like to test some main effects and interactions, but first of all I have tried to compare two conditions ignoring the others (just as a practice before combining the conditions for a more theoreticaly relevant comparison).

To this aim, I have created a cell array in which I have stored the normalized frequency power for each of the 20 participants. In this way I get a cell array with 8 conditions, each containing 20 cells (one per participant).

Here is what I did:

cfg = [];
cfg.layout=layout;
cfg.method = 'template';
cfg.template = 'C:\Fieldtrip\template\neighbours\easycapM1_neighb.mat';
cfg.feedback = 'yes';
cfg.elecfile = 'C:\Fieldtrip\template\electrode\easycap-M1.txt';
neighbours = ft_prepare_neighbours(cfg);

subj = 20;
design = zeros(2,2*subj);
for i = 1:subj
design(1,i) = i;
end
for i = 1:subj
design(1,subj+i) = i;
end
design(2,1:subj)        = 1;
design(2,subj+1:2*subj) = 2;

cfg = [];
cfg.channel          = {'all'};
cfg.frequency        = [4 12];
cfg.latency          = [0 1.5];
cfg.method           = 'montecarlo';
cfg.statistic        = 'depsamplesT';
cfg.correctm         = 'cluster';
cfg.clusteralpha     = 0.05;
cfg.clusterstatistic = 'maxsum';
cfg.minnbchan        = 2;
cfg.tail             = 0;
cfg.clustertail      = 0;
cfg.alpha            = 0.05;
cfg.numrandomization = 500;
cfg.design   = design;
cfg.ivar     = 2;
cfg.uvar = 1;
cfg.neighbours = neighbours;

stat1 = ft_freqstatistics(cfg,  normalized{1,1}{:}, normalized{1,2}{:});

So far so good. Following the online tutorial I have tried to execute the following code:

sigposmask = (stat1.posclusterslabelmat==1) & stat1.mask;
signegmask = (stat1.negclusterslabelmat==1) & stat1.mask;

cfg = [];
cfg.frequency  = [4 12];
cfg.avgoverrpt = 'yes';
cfg.parameter  = {'powspctrm','powspctrm_b'};
WDW_avg = ft_selectdata(cfg, normalized{1,1}{:});
CDW_avg = ft_selectdata(cfg,  normalized{1,2}{:});

WDW_avg.mask = signegmask;
CDW_avg.mask = signegmask;

cfg = [];
cfg.elec          = elec;
cfg.colorbar      = 'no';
cfg.maskparameter = 'mask';  % use the thresholded probability to mask the data
cfg.maskstyle     = 'box';
cfg.parameter     = 'powspctrm_b';
cfg.maskfacealpha = 0.5;

figure; ft_multiplotER(cfg, WDW_avg, CDW_avg);

However, when I try to run the line:

WDW_avg = ft_selectdata(cfg, normalized{1,1}{:});
there are no repetitions, so averaging is not possible

I have therefore tried to remove the {:}, but still:

WDW_avg = ft_selectdata(cfg, normalized{1,1};
Invalid input argument of type 'cell'. Input must be a structure or a Java or COM object

I do understand the errors, but I don’t see how the data should have been stored if not in a cell array. Can someone help?

Thank you in advance,
Luca

Inviato da Posta<https://go.microsoft.com/fwlink/?LinkId=550986> per Windows 10

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