[FieldTrip] Cluster Permutation Data Formatting

Tavabi, Kambiz TAVABIK at email.chop.edu
Mon Dec 13 17:33:50 CET 2010

Greetings, I am using the recommendations on http://fieldtrip.fcdonders.nl/tutorial/cluster_permutation_timelock#within-subjects_experiments to carry out within-subjects permutation tests on MEG data from 10 subjects in a 2x2 design. Briefly, for each subject I have the conditional source-space (2 virtual electrodes) time-frequency representations computed between 1.5-80Hz (0.5 freq step) using Morlet wavelets throughout the stimulus duration (i.e., trial epochs from -0.8 - 1.6 sec). As per tutorial I have created data structures, which to the best of my knowledge are suitable for use with ft_freqstatistics(cfg, cond1, cond2). Also, I have minimally modified the routine in the tutorial to create the cfg structure. As the final state of the dataset was not arrived at using the FT pipeline I am afraid there might be input structure field(s) I may have not defined, or defined incorrectly (e.g. channel labling and layout). Essentially I simply wish to run the tests and view results on two time-frequency representation plots (eg., imagesc)! I would very much appreciate if someone with more experience in these routines would take a look at my script (see attachment) and e.g. data structure and let me know what is missing and/or wrong with them.

ExpHi =
         freq: [1x158 double]
         time: [1x2880 double]
    powspctrm: [4-D double]
       dimord: 'subj_chan_freq_time'
        lable: {2x1 cell} (ie., {['MLT']; ['MRT']}

size(ExpHi.powspctrm) =
          10           2         158        2880 (i.e., Subjects x channes x freqs x timepoints)

Currently I am recieving the following errors

??? Reference to non-existent field 'label'.
Error in ==> prepare_timefreq_data>forcedimord at 509
  output.label  = input.label;
Error in ==> prepare_timefreq_data at 87
  [remember{c}, hascrsspctrm] = forcedimord(varargin{c}); Error in ==> statistics_wrapper at 217
  [cfg, data] = prepare_timefreq_data(cfg, varargin{:}); Error in ==> ft_timelockstatistics at 117 [stat, cfg] = statistics_wrapper(cfg, varargin{:});

Kambiz Tavabi PhD
Biomedical Imaging Laboratory
The Children's Hospital of Philadelphia
34th Street and Civic Center Boulevard
Philadelphia, Pa. 19104
Tel: 267.426.0302
email: tavabik at email.chop.edu

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