Task-based functional MRI (tb-fMRI) is a relatively new type of test, which has FDA approval, and is broadly available.  Is shows where brain networks, such as those that control language or movement are located.  Generally, the patient needs to be awake and reliably able to perform tasks such as language testing while in the MRI machine.  In HH, it is not generally performed unless the team is concerned seizures are coming from somewhere besides the HH and want to know where brain networks are located near proposed seizure onset zones.