A study of analysis parameters that influence the sensitivity of event-related fMRI analyses

To assess the effect of various analysis parameters on the sensitivity of e vent-related fMRI analyses, 36 analyses were performed on a single fMRI dat a-set, varying parameters along four axes: (1) resampled voxel size; (2) sp atial smoothing; (3) temporal smoothing; and. (4) the set of basis function s used to model event-related responses. Sensitivity (i.e., the probability of detecting an activation given it exists) was assessed in terms of Z sco res and by a metric for corrected P values,. the negative log of the expect ed Euler characteristic. Sixteen brain regions distributed across cortical and subcortical areas were included in the meta-analysis. Main effects on s ensitivity were found for resampled voxel size, spatial smoothing, temporal smoothing, and the set of basis functions chosen. The analysis parameters that generally produced the most sensitive analyses were a 2-mm(3) resample d voxel size, 10-mm spatial smoothing, 4-s temporal smoothing, and a basis set comprising a hemodynamic response function and its temporal derivative. (C) 2000 Academic Press.