Also note (tangentially) that if you're playing with haemodynamic models and seeking further options, the AFNI distribution includes the program "balloon" which implements the fluid physics-based model of Buxton, Wong & Frank.
--
Matthew Belmonte <belmonte at mit.edu> [
www.mit.edu]
Assistant Professor, Department of Human Development, Cornell University
G62A Martha Van Rensselaer Hall, Ithaca, NY 14853-4401