Effects of Varying Spatial Disparities on Multisensory Integration During Movement Planning

Abstract

Proprioception is essential for body awareness and motor planning; however, its role in multisensory integration during movement planning remains poorly understood. Most existing tests only assess conscious proprioception through position-matching and localization tasks, overlooking the role of proprioception in movement planning, which occurs at a largely unconscious level. We recently developed a method to reverse engineer arm-position (REAP) estimates during movement planning. Here, we used this method to investigate how varying spatial disparities between visual and proprioceptive cues influence arm-position estimates during movement planning. Using the KINARM End-Point Lab and an extended-reality (XR) display, participants performed reaching movements while a visual hand cue was shifted in one of eight directions at three magnitudes (0.02, 0.04, or 0.06 m). Participants completed 640 trials within the controlled XR environment while visual feedback of their actual arm was occluded. Kinematic data was recorded at 1 kHz and analyzed to quantify directional biases relative to a baseline condition with no visual-proprioceptive cue disparity. Analyses focused on how the magnitude and direction of visual shifts influenced the weights of visual and proprioceptive cues during movement planning. Preliminary results aligned with previous multisensory integration studies using perceptual tasks, in that visual and proprioceptive weights varied with both the direction and magnitude of cue shifts. These findings suggest that the REAP procedure can be used to augment perceptual reporting in multisensory position sensing assessments.

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