Functional Imaging Techniques (PET and fMRI) PET and fMRI scans provide information about the function of the brain by revealing which brain areas become more or less active in different conditions. The PET scan (directly above) shows areas in the left hemisphere (Broca’s area, left; lower parietal–upper temporal area, right) that become active when people hold in mind a string of letters for a few seconds. The red areas in the fMRI scans (all views to the left) indicate activity in the auditory cortex of a person listening to music.