Hi Rick,
Thanks for your reply. Yes, we have four runs and you are right about the regressors. Do you think for example, I should include motion regressors or not? I don't know if there is a standard way of doing "IM" analysis. I note that we have a fast event-related design where the stimuli are auditory and last 180ms or less. Also the ITI is for 8-16s with a TR=2s. There is overlap of the HDRs but there is at least 8 s between stimuli and we assume that the response is pretty much baseline by after 12s. Now the question becomes since I tried using 7 tps (6 TR) originally in "IM" but it can't solve the problem, I then decided on 3 coefficients instead. Do you think the 'IM" program gives reasonable results with TENT for 3 middle tps?
If not, what do you think I should do??? Is there any alternative? Do you have any guidelines to follow for which one would be pretty sure that "IM" works? This whole procedure seems uncertain. I would like an estimation of the peak response of individual trials, have any other suggestions?
I thank you very much for your help on this.
-Linda