artifact threshold and TFR trial length

[Andrew Smart]

Hi,

In the artifact_threshold hold function it says one should specify the thresholds or range in uV/T,
is this µV/T? And what are useful values for this function for MEG data? I have been trying different 
values but could use some guidance.

Also, I have a dataset from a CTF 275 channel machine using epoched recording (ie non-
continuous) and it was recorded with only a 100 ms prestimulus baseline and a 900 ms post-stim 
length. I would like to do  time-frequency and beamforming analysis but am having trouble. So far 
for example I have used this code to look at the alpha frequency, but would like to look at all 
frequencies:

load PreprocData

cfg = [];                                           
cfg.toilim = [0 0.5];    %t to avoid NaNs in the ouput                     
datacond1 = redefinetrial(cfg,dataSP);

cfg = [];
cfg.method='mtmfft';
cfg.output='powandcsd';
cfg.tapsmofrq=4;
cfg.foilim =[10 12];
freqcond1 = freqanalysis(cfg,datacond1);

Do you have any suggestions for this situation? Is the trial length simply too short for using the 
TFR functions? 

Thank you!
andy

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