Dear list,
Dear faculty,
Am I correct that the canonical HRF that is used in SPM fmri to convolve
the datamatrix is in SPM.xBF.bf?
If so, i was wondering what are the units of the rows in SPM.xBF.bf?
And where does this number of rows come from, since it seems to be
varying with TR?
Related to this: Are the units of SPM.xBF.length in seconds? .length
varies with the length of .bf, but which one is dependent on which one?
And finally: Why is the initial undershoot not modeled by this canonical
function? Is its influence negligible?
Many thanks,
--
Bjorn Roelstraete
Ghent University
Department of Data-analysis
H. Dunantlaan 1, B-9000 Gent, Belgium
Tel: 32-9-2646434
E-mail: [log in to unmask]
|