Kira N. Noad¹, Marie-Luise Kieseler², David M. Watson¹, Brad Duchaine², Timothy J. Andrews¹; ¹University of York, ²Dartmouth College

Hyperfamiliarity for faces is a rare condition characterised by an abnormal sense of familiarity for unknown faces. Disorders of face recognition can provide insights into the brain regions involved in the neural representation of familiar faces. Here, we describe a 49-year-old woman (JP) who began experiencing hyperfamiliarity after a severe migraine. She reports having a strong sense of familiarity for faces of people that she does not know, which was not evident before the onset of the disorder. To determine the neural correlates of hyperfamiliarity, we compared the neural responses of JP with neurotypical participants. Structural MRI scans failed to reveal any discernible abnormalities. We then measured fMRI responses in the core face-selective regions to images of unfamiliar faces. JP showed a normal pattern of face-selective responses in the core face regions of the visual brain. To explore the neural response to faces in a more naturalistic setting, we recorded fMRI responses during movie watching. JP watched a movie composed of clips from the TV series Game of Thrones (GoT), which she had not seen before. We measured the response across different regions of the brain in JP and neurotypical participants who were either familiar or unfamiliar with GoT. We found neural responses in the medial temporal lobe of JP were more like familiar participants than unfamiliar participants. We also found that functional connectivity between core face regions and the medial temporal lobe in JP was more like familiar participants than unfamiliar participants. Together, these results demonstrate that hyperfamiliarity for faces manifests in both visual and non-visual parts of the brain, and that connectivity between these regions may play a critical role in the recognition of familiar faces during natural viewing.