Hi,
I have a question that appears related a query about “strange dips” in the August 1st 2007 FSL
digest. In my design subject ratings are used as a Custom 1 predictor. The subjects are presented
with a long duration thermal stimulus (270 second cycle). Subsequently, the subject rating is often
constant at the beginning of each scan. Unfortunately, a initial “spike” artifact appears in the ev
after it is convolved with an HRF. While I can make this problem "go away" by not convolving with
the HRF, I would like to know if there anything else that I can do.
Regards,
Kent Conover,
Research Associate,
Centre for Studies in Behavioral Neuribiology,
Concordia University,
Montreal, Canada
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