Basic neural processing mechanisms of live human face viewing

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Project Summary Significance. The human brain has a dedicated neural system for processing other humans. However relatively little is known about the basic mechanisms of this processing. Prior research has found that live human face viewing results in more activity in the right temporoparietal junction (TPJ) than does viewing a face simulation like a robot face. This suggests that live faces have characteristics that transcend appearance, motion, co- presence, and embodiment which give them access to sociocognitive systems that face simulations cannot access. Research question. What are the neural mechanisms of this access and how do they relate to stimulus acquisition? Further, how might these mechanisms contribute to dysfunction in psychiatric illnesses like schizophrenia? Addressing these gaps in the literature requires skills in: (1) multimodal data acquisition; (2) advanced analytics; and (3) experimental design for clinical populations. To pursue these questions long-term by becoming an independent researcher, I propose a two-phase training plan. In Aim 1, I will supplement existing skills for multimodal experimental design, acquisition, and preprocessing with intermediate multimodal analytics, advanced programming, dataset management, and professionalization. Approach. I will do this with a study on neurotypical neural processing during live human face viewing with robot face viewing as control and will acquire simultaneous functional Near Infra-Red Spectroscopy (fNIRS), electroencephalography (EEG), eye-tracking, and pupillometry. I will then apply eye-behavior-guided time frequency decomposition of EGG data, cross- frequency phase-amplitude coupling, and fNIRS-constrained EEG source localization. Hypotheses. Visual sensing is an active component of the neural processing of live faces. If true, then we hypothesize that eye movements and pupil size during live face viewing will be greater due to increased attention and arousal and greater acquisition of meaningful information from a live face. These differences are hypothesized to correspond to increased power in gamma (30-100hz)—reflecting configural processing—and theta (4-8hz)—reflecting perceptual binding. These frequencies are hypothesized to be coupled to each other—reflecting information transfer from local to global processing—and to localize to regions identified with fNIRS contrasts of live face and robot face viewing. This will identify the temporal and spatial features of the social processing network. Preliminary Results. Participants show greater pupil size and differences in dwell time during live face viewing. Right-TPJ-localized theta band power is greater during live face than robot face viewing. Aim 2, I will complete post-doctoral training on experimental design for those with schizophrenia and on advanced computational analytics like factor analysis and predictive coding. I will do this through research on live face viewing paradigms, such as emotional expression or direct gaze perception, during multimodal data acquisition with a population of patients and non-patients. This training will give me the skills necessary for long term research independence to explore the role of social neurocognitive function and dysfunction in health and psychiatric illness.