Michael Marxen1,2, Ryan J. Cassidy1,
Tara L. Dawson1, Bernhard Ross1,2, Simon J. Graham1,2
1Rotman Research Institute, Baycrest,
Toronto, Ontario, Canada; 2Heart and Stroke Foundation Centre for
Stroke Recovery, Toronto, Ontario, Canada
BOLD
fMRI time courses for somatosensory stimuli of variable lengths are modeled
using the general linear model with a latency optimized hemodynamic impulse
response function and three different neuronal input functions: boxcar (model
A), boxcar + offset transient (model B), onset transient + boxcar + offset
transient (model C). Only model C is capable of fitting the bimodal nature of
the response to the 7s stimulus and the relative peak amplitudes for all
stimulus lengths in key areas of the somatosensory-motor system. Therefore,
including onset and offset transients provides a more comprehensive picture
of the underlying brain activity.
Keywords