Patent Issue: NEED HELP

We have a project which is a collabrative project with a big institute. The project is funded by NSF. We are the sub-PI. During this period, we have some new discoveries which we think they may be patentable.So we are thinking to apply the patent. But we don't know if these new technologies belong to the PI institute which is the big institute? Or do we have to apply the patent through the PI institute? Is there any law to talk about this? Thanks a lot!