¥ STEP
5: Perform a deconvolution analysis
on Subject EDÕs data with 3dDeconvolve
G
GWhat is the difference between regular linear regression
and deconvolution analysis?
åWith linear
regression, the hemodynamic response is
already assumed (we can get a fixed
hemodynamic model by running the AFNI waver program)
åWith deconvolution
analysis, the hemodynamic response is
not assumed. Instead, it is computed by 3dDeconvolve from the data
íOnce the HRF is modeled by 3dDeconvolve, the program then runs a
linear regression on the data
íTo compute the hemodynamic response function with 3dDeconvolve, we include the ÒminlagÓ
and ÒmaxlagÓ options on the command
line
¥The
user (you) must determine the lag time of an input stimulus
¥1
lag = 1 TR = 2 seconds
åIn this example, the lag time of the input stimulus has
been determined to be about 15 lags
íAs such, we will add a ÒminlagÓ of 0 and a ÒmaxlagÓ of
14 in our 3dDeconvolve command