HCP Dataset Loader - Hemodynamic Lag

In the HCP dataset loader there is a skip argument in the condition_frames and selective_average functions. However, it is not being set further down in the code. Does anyone know whether it has been already accounted for the hemodynamic lag in some other preprocessing step? Thanks in advance!

I tried changing the skip value, but it didn’t seem to alter my task results at all.

Ooops, that’s because selective_average is not passing it down to condition_frames

Yes, that I fixed already. However, it is also not used further down: For example in the code for the “Run a simple subtraction analysis” example. Don’t we need to account for hemodynamic lag in this kind of analysis?

For block design tasks, it won’t matter much. But you can set a different value when you call selective_average, if you want.

I see, thanks! As I’m new to fMRI: what would be a reasonable value in this case?

Canonical models of the HRF usually have it peaking ~5 s after stimulus onset.

Alright, thanks a lot for your quick replies! :slight_smile: