Department of Biomedical Engineering, University of California, Davis, CA, USA; Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA; Clinical and Translational Science Center, University of California Davis Health, Sacramento, CA, USA.
Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA.
Neuroscience. 2024 Jun 21;549:24-41. doi: 10.1016/j.neuroscience.2024.02.033. Epub 2024 Mar 13.
Accurate movements of the upper limb require the integration of various forms of sensory feedback (e.g., visual and postural information). The influence of these different sensory modalities on reaching movements has been largely studied by assessing endpoint errors after selectively perturbing sensory estimates of hand location. These studies have demonstrated that both vision and proprioception make key contributions in determining the reach endpoint. However, their influence on motor output throughout movement remains unclear. Here we used separate perturbations of posture and visual information to dissociate their effects on reaching dynamics and temporal force profiles during point-to-point reaching movements. We tested human subjects (N = 32) and found that vision and posture modulate select aspects of reaching dynamics. Specifically, altering arm posture influences the relationship between temporal force patterns and the motion-state variables of hand position and acceleration, whereas dissociating visual feedback influences the relationship between force patterns and the motion-state variables of velocity and acceleration. Next, we examined the extent these baseline motion-state relationships influence motor adaptation based on perturbations of movement dynamics. We trained subjects using a velocity-dependent force-field to probe the extent arm posture-dependent influences persisted after exposure to a motion-state dependent perturbation. Changes in the temporal force profiles due to variations in arm posture were not reduced by adaptation to novel movement dynamics, but persisted throughout learning. These results suggest that vision and posture differentially influence the internal estimation of limb state throughout movement and play distinct roles in forming the response to external perturbations during movement.
上肢的精确运动需要整合各种形式的感觉反馈（例如视觉和姿势信息）。通过选择性地干扰手部位置的感觉估计，已经对这些不同感觉模式对伸手运动的影响进行了大量研究。这些研究表明，视觉和本体感觉在确定伸手终点方面都有重要贡献。然而，它们对运动过程中运动输出的影响仍不清楚。在这里，我们使用姿势和视觉信息的单独干扰来区分它们对点对点伸手运动中的动态和时间力曲线的影响。我们测试了人类受试者（N=32），发现视觉和姿势调节了伸手动态的某些方面。具体来说，改变手臂姿势会影响时间力模式与手部位置和加速度运动状态变量之间的关系，而分离视觉反馈会影响速度和加速度运动状态变量与力模式之间的关系。接下来，我们研究了这些基线运动状态关系在基于运动动力学的运动适应中的影响程度。我们使用速度相关力场训练受试者，以探究在暴露于依赖运动状态的干扰后，手臂姿势依赖的影响持续的程度。由于手臂姿势的变化导致的时间力曲线的变化并没有通过对新运动动力学的适应而减少，但在整个学习过程中都持续存在。这些结果表明，视觉和姿势在运动过程中不同地影响肢体状态的内部估计，并在运动过程中对外部干扰的反应形成中发挥不同的作用。
