This is actually a pretty big question concerning deconvolution and the GLM. But basically, the analysis knows what the overlap is since you tell it which stimulus is presented when and what the shape of the HDR looks like. The analysis then computes the amplitude of the HDR for each condition, which is what is reported in the roi summary.
Cameron Ellis wrote:
Hi, I am running an ROI analysis on a set of event-related data obtained through spmhrf analysis. When I run roisumamry-sess to obtain the values needed to calculate a percent signal change the number of estimations per condition is 1, which makes sense since I am looking at the entire time window. I have three conditions, however, and only three numbers corresponding to each condition to be used in a total % signal change calculation are generated. My question is, how are these overall values for each condition calculated? More specifically, how are the TRs assigned to a particular condition to calculate a value specifc to a condition when each condition overlaps within the timewindow? Thanks in advance to anyone who can help, Cameron _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer