Audiovisual integration in macaque face patch neurons

Primate social communication depends on the perceptual integration of visual and auditory cues, reflected in the multimodal mixing of sensory signals in certain cortical areas. The macaque cortical face patch network, identified through visual, face-selective responses measured with fMRI, is assumed to contribute to visual social interactions. However, whether face patch neurons are also influenced by acoustic information, such as the auditory component of a natural vocalization, remains unknown. Here, we recorded single-unit activity in the anterior fundus (AF) face patch, in the superior temporal sulcus, and anterior medial (AM) face patch, on the undersurface of the temporal lobe, in macaques presented with audiovisual, visual-only, and auditory-only renditions of natural movies of macaques vocalizing. The results revealed that 76% of neurons in face patch AF were significantly influenced by the auditory component of the movie, most often through enhancement of visual responses but sometimes in response to the auditory stimulus alone. By contrast, few neurons in face patch AM exhibited significant auditory responses or modulation. Control experiments in AF used an animated macaque avatar to demonstrate, first, that the structural elements of the face were often essential for audiovisual modulation and, second, that the temporal modulation of the acoustic stimulus was more important than its frequency spectrum. Together, these results identify a striking contrast between two face patches and specifically identify AF as playing a potential role in the integration of audiovisual cues during natural modes of social communication. [Display omitted] •Audiovisual integration was examined among neurons in macaque AF and AM face patches•Most neurons in AF were modulated by the acoustic component of macaque vocalizations•Acoustic modulation in AF was contingent on visual facial structure•Very few neurons in AM exhibited auditory responses or modulation Khandhadia et al. examine neural responses in two macaque face patches (AF and AM) to audiovisual renditions of vocalizing macaques. They find that the auditory component consistently modulates face-selective, single-unit activity in AF, but not in AM, suggesting an important role for AF in the audiovisual integration of social stimuli.