Carly Gregg¹ (), Kenji Koyano², Will Robison¹, Jess Taubert³, David Leopold¹; ¹Section on Cognitive Neurophysiology and Imaging, NIMH, ²Advanced Neuroimaging Center, QST, ³School of Psychology, The University of Queensland

Facial recognition, a critical skill in primate social behavior, is supported by specialized brain areas in the temporal and frontal cortices. We previously reported that neural responses in face-selective regions of the inferior temporal cortex, including the anterior fundus (AF) and anterior medial (AM) face patches, are shaped by both average facial structure and local feature details. The same neural populations exhibited minimal selectivity for pareidolia stimuli, namely objects whose internal configural arrangements cause them to resemble faces. The aim of the present study is to replicate and extend these findings in additional face patches in the temporal and frontal cortex. In two male Rhesus macaques, we used fMRI to localize the AM and perirhinal (PRh) face patches in the temporal cortex and the orbitofrontal cortex (PO) and frontal pole (FP) face patches in the prefrontal cortex. We implanted one 64-channel chronic brush electrode into each patch in both animals. We simultaneously recorded single-unit responses from the four areas to (1) identity morphed faces, (2) feature-recombined faces, and (3) pareidolia images. For the identity morphing experiment, animals viewed macaque and human faces across identity levels including caricatures (exaggerated identity), antifaces (negative identity), and near-average faces. Responses in frontal vs. temporal lobe face patches were generally similar for these stimuli, exhibiting V-shaped tuning around the average face. For the local features experiment, a set of 10 images was broken into component parts (eyes, nose-mouth, outer face, etc.) and recombined to create a set of 450 images which the animals viewed. Preliminary analysis shows that AM and PRh neurons are more strongly driven by local features than the frontal cortex face patches. Lastly, all cells responded only weakly to pareidolia stimuli. Together, these results highlight a significant overlap in response selectivity among fMRI-identified face patches in the temporal and frontal cortices.