Publications [#252333] of Scott Huettel

Journal Articles

1. Huettel, SA; McCarthy, G (2001). The effects of single-trial averaging upon the spatial extent of fMRI activation.. Neuroreport, 12(11), 2411-2416. [doi]
   (last updated on 2026/01/16)

   Abstract:
   We examined effects of trial averaging upon spatial extent, spatial topography, and temporal properties of fMRI activation. Two subjects participated in an event-related visual stimulation design. There was an exponential relation between number of trials and spatial extent, such that additional trials identified, on average, a constant proportion of the remaining voxels. At values typical of fMRI experimentation (e.g. 50 trials) only about 50% of eventually active voxels were significant; asymptotic values were approached by 150 trials. The variability of the estimated hemodynamic response decreased with signal averaging, becoming stable across samples of > or = 25 trials. Therefore, group or condition differences may result from differences in voxelwise noise exacerbated by averaging small numbers of trials.