Minimal impact of chronic proprioceptive loss on implicit sensorimotor adaptation and perceived movement outcome

AbstractImplicit sensorimotor adaptation keeps our movements well-calibrated amid changes in the body and environment. We have recently postulated that implicit adaptation is driven by a perceptual error: the difference between the desired and perceived movement outcome. According to this perceptual re-alignment model, implicit adaptation ceases when the perceived movement outcome – a multimodal percept determined by a prior belief conveying the intended action, the motor command, and feedback from proprioception and vision – is aligned with the desired movement outcome. Here, we examined the role of proprioception in implicit motor adaptation and perceived movement outcome by examining individuals who experience deafferentation (i.e., individuals with impaired proprioception and touch). We used a modified visuomotor rotation task designed to isolate implicit adaptation and probe perceived movement outcome throughout the experiment. Surprisingly, both implicit adaptation and perceived movement outcome were minimally impacted by chronic deafferentation, posing a challenge to the perceptual re-alignment model of implicit adaptation.摘要：隐性感觉运动适应（implicit sensorimotor adaptation）可使机体在身体与环境发生变化时，始终维持运动的精准校准状态。本研究团队近期提出假说，认为隐性适应由感知误差（perceptual error）驱动，即预期运动结果（desired movement outcome）与感知运动结果（perceived movement outcome）之间的差值。根据该感知重校准模型（perceptual re-alignment model），当感知运动结果——这一多模态感知（multimodal percept）由表征预期动作的先验信念（prior belief）、运动指令（motor command）以及本体感觉（proprioception）与视觉反馈共同构成——与预期运动结果对齐时，隐性适应便会终止。本研究通过考察存在传入神经阻滞（deafferentation）的个体（即本体感觉与触觉受损人群），探究了本体感觉在隐性运动适应与感知运动结果中的作用。实验采用改良式视觉运动旋转任务（modified visuomotor rotation task），以分离隐性适应并在实验全程探查感知运动结果。令人意外的是，慢性传入神经阻滞对隐性适应与感知运动结果均仅产生极轻微的影响，这对隐性适应的感知重校准模型构成了挑战。