[FieldTrip] Problems time-frequency analysis of Local Field Potential

[chenzuyue]

Hi, everyone,
I am a new user of FieldTrip. In my
study, I want to computes the difference of time-frequency
representations of event-related LFP in two conditions.
The data in the first condition is a 4
X 1100 X 103 matrix (Nchan X Nsamples X Ntrials).  The data in the
second condition is a  4 X 1100 X 107 matrix. The data reformatted
are as follows:
dataset1.label   (4 X 1 cell );
dataset1.fsample 1000;
dataset1.trial (1 X 103 cell );
dataset1.time (1X 103 cell);           
   % time is from -100ms to 999ms.



dataset2.label   (4 X 1 cell );
dataset2.fsample 1000;
dataset2.trial (1 X 107 cell );
dataset2.time (1X 107 cell );          
    % time is from -100ms to 999ms.



 The frequency interested is 0-100Hz.
The method to calculate TFRs is the multitaper method. The
configuration is as below:
cfg = [];
cfg.output     = 'pow';
cfg.method     = 'mtmconvol';
cfg.foi        = 1:2:100;
cfg.t_ftimwin  = 5./cfg.foi;
cfg.tapsmofrq  = 0.4 *cfg.foi;
cfg.toi        = -0.1:0.05:1;
cfg.pad        = 'maxperlen';  
TFRmult1 = ft_freqanalysis(cfg, dataset1);
But after running, I can not get the right results. When I use
ft_singleplotTFR to plot graph, there is only blue color. I wonder
whether the process and configuration is right. 

The method is from one paper of E Maris
and R Oostenvels published on the Journal of Neuroscience
Methods.164(2007), 177-190; Figure 3.
http://www.ncbi.nlm.nih.gov/pubmed/17517438
Any help is much appreciated.
Yours Sincerely,
Zuyue

 		 	   		  
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