HI all, 

I have a animal model that I would like to use for an fMRI experiment.  The disease model we use  requires a bolus injection of heparin at the start. I'm wondering if I measure the change in bold signal over time with a heparin challenge can I create a regressor model for the heparin? Alternately if all my animals have the same injection of heparin at the same time will it regress itself out, or should I shoot to have the heparin in a steady state before we start scanning?

Thanks, 

austin