Hi,
I have what I believe are two relatively simple questions:
My fMRI study consists of an event-related design in which stimuli are presented every 20 seconds. There are two different experimental conditions and a control condition.
Using SPM99, I have been playing around with plotting event/epoch related responses in an attempt to create a graph that plots the average activation timecourse – over a 20 sec. window – at a selected voxel for all the trials in a given condition.
I seem to have no control over the amount of time on the x axis. For my experiment, it appears to be set at a 35 sec time frame. Is there any way I can change this?
Also, when the slope of my graph is negative, does that imply less activation in the given experimental condition than the control?
Many thanks,
Susan McLaughlin
Dept. of Speech and Hearing Sciences
University of Washington
|