[FieldTrip] Pre-stimulus baseline correction for response-locked ERPs

[Marijke Beulen]

Dear all,

I was wondering if anyone knows how to define a stimulus-locked baseline period to correct a response-locked ERP using ft_timelockbaseline.

So far, I've been plotting stimulus-locked ERPs and using ft_timelockbaseline with the 300ms before stimulus onset for baseline correction. I've tried other methods to do baseline correction manually, but so far, ft_timelockbaseline has given me the best results. However, now I also want to plot response-locked ERPs. To keep things comparable, I would like to use the same 300ms pre-stimulus interval for baseline correction, but my trials have different lengths. This means that after response-locking the data, the time stamp of that interval is different on every trial. Is there any way to e.g. define separate baseline windows for each trial or to give FieldTrip another (stimulus-locked) dataset to use as a baseline in ft_timelockbaseline?

I've already searched through FieldTrip's documentation, but I haven't been able to find a solution. Any advice on how to do this would be much appreciated!

Sincerely,

Marijke Beulen

--
M.A. Beulen, MSc.
PhD student at University of Groningen, dept. Artificial Intelligence
Bernoulliborg, room 320
Nijenborgh 9
9747 AG Groningen 
The Netherlands
Phone: +31 50 363 6915
m.a.beulen at rug.nl

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