Dave,

Thanks for the careful response!

I should apologize, again, as I think my imprecision in wording may have led to some misunderstanding. But I think I have it cleared up now. Just to be sure:

* Although "impulse response function" can be used to describe, say, a characteristic HRF when an instantaneous stimulus is applied, this is not the sense in which it's being used here. Here we are referring to the _observed_ estimated impulse response, calculated on a per-voxel basis, per regressor. This was my main confusion.

* I might consider using Tent basis functions in place of my usual Gamma model -- perhaps because it's easier to bound my time intervals this way?

Hopefully I've gotten it right this time. Thanks for bearing with me!

Cheers,
A