Such an option with 3dDeconvolve has been discussed for a while, and we are now working on implementing it into AFNI.

However, if you have access to Matlab, here is a workaround solution to the option of gamma variate and its time derivative with 3dDeconvolve:

(1) Create a directory (e.g., matscript), and get the package at the following location to the new directory you just created:

[afni.nimh.nih.gov]

(2) Unpack the tarred file with the following command:

tar xvzf afni_matlab.tgz

(3) Set the matlab path appropriately. For csh or tcsh users, add the directory to the MATLABPATH environment variable. If you don't know to do this, ask somebody such as your system administrator for help.

(4) Go to the directory where you want to run regression analysis of some dataset, start Matlab and type "Decon" at the prompt. You will be asked a bunch of streamlined and interactive questions, which would lead you to running 3dDeconvolve with various options including basis functions of gamma variate and its derivative.

Let me know if it works for you.

Gang