¥ In each voxel, fit data Zn to a curve of the form
¥
¥ bj is amplitude in data of rn(j)=rj(tn) ; i.e., Òhow muchÓ of j th response function in in the data time
series
¥ In simple regression, each rj(t ) is
derived directly from stimulus timing and
user-chosen HRF model
¥ In terms of stimulus times:
¥ If stimulus occurs on the imaging TR time-grid, stimulus can be
represented as a 0-1 time series:
¥
where sk(j)=1 if stimulus #j is on
¥ at time t=k ×TR, and sk(j)=0 if #j is off at that
time: