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73. The Value of Nuance: Aberrations to Fine Motor Control in Psychosis as Assessed via Sensorimotor Synchronization
While the cerebellum has been implicated in the pathophysiology of psychosis, the specific role of cerebellar systems in sensorimotor disturbances in psychosis is not well characterized. Sensorimotor synchronization during tapping, a task for which many basic processes need to be engaged to execute a behavior, can allow parsing of cerebellar contributions to specific, sub-components. In the present study, (1) fine-resolution tapping characteristics of force, initiation time, and impulse (AUC) were derived from gross behavior to determine cerebellar contributions to these sub-components and (2) were compared between healthy control and psychosis samples to pinpoint processes vulnerable to atypical development. The psychosis group (N=10 schizophrenia, 7 schizoaffective) exhibited less adaptive self-paced tapping control as evidenced by higher impulse, a lack of impulse optimization over the course of the task, and increased latency to tap initiation compared to controls (N=13). Initiation latency optimization was negatively correlated with cerebellar activation in both samples and predicted by cerebellar activation and clinical phenomenology (i.e., PANSS negative symptoms) in the psychosis group. The current findings quantify differential cerebellar contributions to a task and further develop a model of sensorimotor dysfunction, which can be evaluated by fine-resolution, sub-component measures.