BOLD Impulse Response Model
•    Function of blood oxygenation,
    flow, volume (Buxton et al, 1998)
•    Peak (max. oxygenation) 4-6s
    poststimulus; baseline after 20-30s
•    Initial undershoot can be observed
   (Malonek & Grinvald, 1996)
•    Similar across V1, A1, S1…
•    … but differences across:
    other regions (Schacter et al 1997)
    individuals (Aguirre et al, 1998)

Columbia  fMRI