> In the documentation it indicates that the iresp option estimates the HRF at each
> voxel at each time point, but I don't know what the estimate means - is it the
> peak amplitude? the auc of the HRF?

Neither. The output from -iresp is the estimated response curve based on the weighted linear combination of the basis functions (SIN in your case) with weights being the beta values. If you want the UAC, you can sum up the values from -iresp using "3dTstat -sum" as Daniel suggested.

> Now, I know that if I average together a few sequential sub-briks from one of the
> iresp files and then divide by the baseline, this gives me a 'percent signal change' file.
> My question is, is this the average percent signal change, or is it an estimate of the
> auc? Not knowing for sure what the iresp sub-brik files represent, I am unsure.

If you have already scaled the BOLD signal by the voxel-wise mean, the UAC value as well as the output from -iresp can be directly interpreted as percent signal change relative to the mean signal. And there is no need for another step of division by the baseline.

Gang



Edited 1 time(s). Last edit at 07/25/2013 10:25AM by Gang.