Well, if the short epoch always immediately precedes the long epoch, then at the beginning of the long epoch, the BOLD signal will already be raised (compared to the "baseline" signal). If you put in a baseline/control block, it will allow it to "go back to 0".
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From: SPM (Statistical Parametric Mapping) [[log in to unmask]] On Behalf Of Talya Sadeh [[log in to unmask]]
Sent: Monday, July 05, 2010 3:08 PM
To: [log in to unmask]
Subject: Re: [SPM] The variable duration epoch method
Thanks so much for your reply, Christopher.
Just another little question - why is it that I need the short and long epochs to be seperated by a control/baseline condition?
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