Abstract：
Congenital unilateral absence of the hand (amelia) completely deprives individuals of sensorimotor experiences with their absent effector. The consequences of such deprivation on motor planning abilities are poorly understood. Fourteen patients and matched controls performed two grip selection tasks: 1) overt grip selection (OGS), in which they used their intact hand to grasp a three-dimensional object that appeared in different orientations using the most natural (under-or over-hand) precision grip, and 2) prospective grip selection (PGS), in which they selected the most natural grip for either the intact or absent hand without moving. For the intact hand, we evaluated planning accuracy by comparing concordance between grip preferences expressed in PGS vs. OGS. For the absent hand, we compared PGS responses with OGS responses for the intact hand that had been phase shifted by 180°, thereby accounting for mirror symmetrical biomechanical constraints of the two limbs. Like controls, amelic individuals displayed a consistent preference for less awkward grips in both OGS and PGS. Unexpectedly, however, they were slower and less accurate for PGS based on either the intact or the absent hand. We conclude that direct sensorimotor experience with both hands may be important for the typical development or refinement of effector-specific internal representations of either limb.
摘要：
先天性单侧缺乏手（amelia）完全剥夺了个体的感觉运动经历，而他们的效应器缺失。人们对这种剥夺对运动计划能力的影响知之甚少。14名患者和匹配的对照组执行了两项握力选择任务：1）公开握力选择（OGS），在其中，他们用他们完整的手抓住三维物体，这些物体使用最自然的（手下或手下）精确的握力以不同的方向出现，和2)前瞻性握力选择(PGS)，在其中，他们选择了最自然的抓地力，无论是完整的手还是不动。对于完好的手，我们通过比较PGS中表达的握力偏好与OGS.对于缺席的手，我们比较了相位偏移180°的完整手的PGS反应与OGS反应，从而考虑了两个肢体的镜像对称生物力学约束。像控件一样，釉质个体在OGS和PGS中均表现出对不那么笨拙的抓握的一致偏好。出乎意料的是,然而,基于完整或不存在的手，它们对于PGS的速度较慢且准确性较低。我们得出的结论是，双手的直接感觉运动体验对于任一肢体的效应器特异性内部表征的典型发展或完善可能很重要。
