Clower D M, Boussaoud D
Research Service (151S), Veterans Affairs Medical Center, Syracuse, New York 13210, USA.
J Neurophysiol. 2000 Nov;84(5):2703-8. doi: 10.1152/jn.2000.84.5.2703.
Exposure to laterally displacing prisms is characterized by systematic misreaching in the opposite direction after prisms are removed. Other learning tasks involving altered visuomotor mappings can often be mastered by the subject with minimal resulting aftereffects. One variable that may account for this difference is the nature of the feedback provided to the subject: during studies of prism exposure, subjects usually view the hand itself, whereas in many studies of visuomotor learning, subjects view a computer-generated representation of the hand position or movement. We compared the use of actual feedback of the hand with computer-generated representational feedback of its position during exposure to laterally displacing prisms. In the actual feedback condition (ACT), a light on the fingertip was illuminated immediately at the end of each reach. In the representational feedback condition (REP), a computer-generated spot of light was displayed to indicate the exact position of the fingertip at the end of each reach. Whereas the rate and magnitude of error correction were the same in both conditions, only the ACT condition produced the large adaptive aftereffect typically observed after prism exposure. These results suggest that the perception of a physical coincidence between the feedback source and the hand may be a key factor in determining whether adaptation is accomplished through perceptual recalibration or visuomotor skill acquisition.
暴露于横向移位棱镜的特征是在移除棱镜后会朝着相反方向出现系统性的伸手误差。其他涉及改变视觉运动映射的学习任务，受试者通常能够以最小的后续影响来掌握。一个可能解释这种差异的变量是提供给受试者的反馈性质：在棱镜暴露研究中，受试者通常观看手部本身，而在许多视觉运动学习研究中，受试者观看的是手部位置或运动的计算机生成表征。我们比较了在暴露于横向移位棱镜期间，手部实际反馈与手部位置的计算机生成表征反馈的使用情况。在实际反馈条件（ACT）下，每次伸手结束时指尖上的灯会立即亮起。在表征反馈条件（REP）下，会显示一个计算机生成的光点，以指示每次伸手结束时指尖的确切位置。虽然两种条件下误差校正的速率和幅度相同，但只有ACT条件产生了通常在棱镜暴露后观察到的较大适应性后效应。这些结果表明，反馈源与手部之间物理重合的感知可能是决定适应是通过感知重新校准还是视觉运动技能习得来实现的关键因素。
