Entrainment of visuomotor responses to target speed during interception.

Motor actions adapt dynamically to external changes through the brain's ability to predict sensory outcomes and adjust for discrepancies between anticipated and actual sensory inputs. In this study, we investigated how changes in target speed (v) and direction influenced visuomotor responses, focusing on gaze and manual joystick control during an interception task. Participants tracked a moving target with sinusoidal variations in v and directional changes, generating sensory prediction errors and requiring real-time adjustments. Our results demonstrate slow variations in v entrained gaze and joystick metrics, with participants synchronizing their responses to the cycles of target motion. While target directional changes alone had limited impact, combining them with sinusoidal variations in v led to robust behavioral entrainment. Participants also exhibited rapid within-trial adjustments, with peak gaze and joystick gains increasing linearly with v frequency, highlighting the critical role of manual control in matching or exceeding v for successful interception. Additionally, responses to sudden phase changes in the v sinusoid revealed the continuous monitoring of prediction errors driven by the magnitude of phase shifts. These findings illustrate the brain's predictive system's ability to integrate continuous visual feedback and sensory prediction errors to fine-tune motor responses and anticipate future target speeds.