Hello all. I am interested in using a custom HRF and separately a custom basis set in SPM5 and would like to enable this option in as elegant a way as possible. I do know that a custom HRF needs to have the correct microtime. The current default is 16 bins/second and I will do that in the creation of the custom functions. Is there a way to add an extra option to the Basis functions pull down when specifying the fMRI 1st level model? Then from there the spm_get_bf function will need to be modified to recognize the new case. Any ideas? Thank you very much Jason Steffener