[FieldTrip] Empty array in coherence connectivity analysis

[Schoffelen, J.M. (Jan Mathijs)]

Yes, and be sure that cfg.channelcmb is an Nx2 cell-array:  {‘somechannel’ ‘someotherchannel’; ‘againsomechannel’ ‘someotherchannelaswell’; ‘etc’ ‘etc’}

Best wishes,
Jan-Mathijs
On 30 Mar 2018, at 18:00, Tobias Staudigl <tobias.stdgl at gmail.com<mailto:tobias.stdgl at gmail.com>> wrote:

Hi Taylor,

First  specify
cfg.output = 'fourier'
Or
cfg.output ='powandcsd'

in your ft_freqanalysis.

Then try ft_connectivityanalysis again.

Best,
Tobias


Am 30.03.2018 17:53 schrieb "Rosa Taylor Beale" <TaylorBealeR at cardiff.ac.uk<mailto:TaylorBealeR at cardiff.ac.uk>>:
Hi all,
I’m a final year undergraduate in Cardiff working on pain networks.
I have been trying to calculate coherence between 3 seed regions, however when I run the ft_connectivityanalysis, the labelcmb and cohspctrm arrays are empty (the channel labels don’t look like they were read?). There is no error or warning messages that occur when running the command, so I am unsure why it is not running correctly.

First, I run ft_freqanalysis which seems to run fine:

cfg = []

cfg.method = 'wavelet';

cfg.output = 'pow';

cfg.toi = 0:0.05:2;

cfg.foi = [30:1:100];

time_freq= ft_freqanalysis(cfg, virtualchannel_raw);

time_freq =

label: {3x1 cell}
dimord: 'chan_freq_time'
freq: [1x71 double]
time: [1x41 double]
powspctrm: [3x71x41 double]
cfg: [1x1 struct]

Then I run the connectivity analysis and up with the empty output:

cfg = [];

cfg.method = 'coh';

cfg.channelcmb = {'pfcCont_seed' 'smc_seed'
                   'pfcIps_seed' 'smc_seed'
                   'pfcCont_seed' 'pfcIps_seed'};

coherence = ft_connectivityanalysis(cfg, time_freq);



coherence =

labelcmb: {0x2 cell}
dimord: 'chancmb_freq_time'
cohspctrm: [0x71x41 double]
time: [1x41 double]
freq: [1x71 double]
cfg: [1x1 struct]


>> coherence.labelcmb

ans =

   Empty cell array: 0-by-2


>> coherence.cohspctrm

ans =

   Empty array: 0-by-71-by-41

I have tried with fieldtrip versions 20161011 and 20171015 on matlab r2015a.

I’ve shown this to various people much more experienced at fieldtrip than I and we’ve all been a bit stumped!
Any ideas?
Many thanks
Rosa Taylor Beale


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