Ð75Ð
¥ Can have
activations with multiple phases that are not always in the same time relationship to each other
H e.g.,
solving a visually presented puzzle:
² subject sees puzzle
² subject
cogitates a while
² subject
responds with solution
¥ With
fixed-shape regression, this isnÕt too hard, since we can treat each phase as a separate stimulus class and lay
down a separate fixed-shape HRF for each
type of stimulus time
H But
fixed-shape regression is probably not reasonable for this problem, since (at least) the ÒcogitationÓ phase
isnÕt fixed among the trials
¥ Deconvolution assumes that the HRF (although unknown) is the same among all trials in the same class
Advanced Topics in Regression
timing of
events
is
measured