[Eeglablist] ahout the ERSP baseline setting

[Lili Wu]

Hello,
  I have a question on the baseline setting of ERSP.
   
  I want to use the eeg before stimulus onset (from a timepoint before the stimulus to the stimulus onset) as the baseline and to compute the ERSP related to the response.
   
  The continuous eeg data was epoched according the stimulus and response.
   
  When the epochs relative to the response were longer than the epochs relative to the stilmulus, the powbase from the stimulus-epoch can not used as the baseline of the response-epoch, for the matrix is not consisten.
   
  But I do not use a very long stimulus-epoch, for example, as long as 1500ms or longer than that. 
   
  Could I segment the stimulus-epoch to be a little longer, such as from a timepoint before the stimulus to a timepoint after the stimulus onset, may be 
  -1000~500ms, and compute the powbase. If the response-epochs are -1200~300ms(response onset as zero), then use the powbase matrix from the stimulus-epochs as the baseline to compute the ERSP, the matrix will be consistent.
   
  I do not know whether this is correct, so I am look for your suggestions.
   
  Lili Wu
   
   
   
   

       
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