Temporal Dynamics of Sensorimotor Integration for Non-Visual Target Information During Movement Preparation and Online Control

Online movement variability in non-visual (auditory and proprioceptive) target reaching is modality-dependent. This study investigated whether such modality-specific effects emerge during movement preparation and whether this phase influences subsequent online control. Participants performed reaching movements toward auditory, proprioceptive, or audio-proprioceptive targets. Electromyography and movement kinematics were recorded to examine the effects of sensory modality on sensory encoding and motor coordination during movement preparation, as well as online control at 5%, 50%, and 100% of movement time. Results revealed a modality-dependent sensory encoding phase, whereas a modality-independent motor coordination phase. Movement variability was greater for auditory targets than for proprioceptive and audio-proprioceptive targets at 50% and 100% of movement. Only motor coordination influenced early online control (5%), but this effect was modality-independent. These findings demonstrate that the influence of sensory modality extends beyond execution to the preparatory phase of movement. The results support a four-stage model of action control: a modality-dependent sensory encoding phase of preparation and late online control, alongside a modality-independent motor coordination phase and early online control. These findings offer new insight into the temporal dynamics of sensorimotor control without vision, indicating that non-visual sensory information is differentially used during distinct phases of movement preparation and execution.