PROJECT SUMMARY The cerebellum has long been thought to solely process motor information. Yet, there is a growing literature that points to a role of the cerebellum in processes across multiple domains. Individuals with cerebellar lesions classically have motor deficits but, in some instances, also have problems with executive functioning, emotion processing, language, and social cognition. Multiple psychiatric disorders, including autism spectrum disorders (ASD), have been linked to structural and functional differences in the cerebellum. Moreover, numerous functional magnetic resonance imaging (fMRI) studies have reported neural responses in the cerebellum related to a host of non-motor tasks. These findings provide evidence that the cerebellum is involved in non- motor tasks, but it remains entirely unclear how the cerebellum contributes to performance on these tasks. F99 Phase: Models have been successfully developed to explain the role of the cerebellum in motor processing. These models emphasize the cerebellum's role as a learning machine that modulates and perfects ongoing processing through the online comparison of reality to an internal model, thereby utilizing sensory prediction errors. Recent findings in humans and mice suggest that portions of the cerebellum are involved in reward processing; a process which has primarily been investigated in regards to the basal ganglia. It is unclear what computational role the cerebellum plays in this reward processing, as the cerebellum has been said to explicitly operate without reward information. To understand this, the present proposal will use fMRI in healthy young adults to study the cerebellum's contribution to both traditional (e.g. monetary) and social reward processing, and to differentiate it from the role of the basal ganglia in reward processing. The training plan for this proposal includes training in computational modeling methods related to reward processing. It also includes training in social neuroscience theories and task design. Computational modeling will allow us to explore parameters that are not easily discernable from behavioral observations of an experiment alone and to directly test theories about the cerebellum's algorithmic processing, by providing insight into the cerebellum's algorithmic computations across multiple task domains, and its role in traditional and social reward processing. These findings will provide insight into the cerebellum's mechanistic capabilities. K00 Phase: Individuals with ASD exhibit deficits in social cognition and in social reward processing. Structural, functional, and connectivity differences have implicated the cerebellum in this disorder, with neonatal cerebellar damage being the second highest predictor of ASD. The K00 phase will investigate how the cerebellum performs in individuals with autism, who have deficits in social reward processing. The training plan in this phase of the proposal will focus on learning computational modeling of reinforcement learning and applying these models to cerebellum functioning with fMRI. The training plan also includes goals to develop mentorship skills to prepare the applicant to establish a diverse and inclusive independent research laboratory.

PROJECT NARRATIVE This project will combine computational modeling and neuroimaging methods to study social and cognitive computations performed by the posterior cerebellum. The F99 phase will examine how the posterior cerebellum uniquely contributes to monetary and social reward processing, improving our basic scientific understanding of the cerebellum's core algorithmic capabilities and revealing the cerebellum's potential range of neural computations. The K00 phase will explore the cerebellum's mechanistic role in autism spectrum disorder through a reinforcement learning framework, providing insight into how a disruption in these processes may cause the canonical social deficits observed in this disorder.