Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Brain Res. 2010 Oct 8;1355:104-11. doi: 10.1016/j.brainres.2010.07.063. Epub 2010 Jul 24.
Previous research with deafferented subjects suggests that efference copy can be used to update limb position. However, the contributions of efference copy to limb localization are currently unclear. We examined the performance of JDY, a woman with severe, longstanding proprioceptive deficits from a sensory peripheral neuropathy, on a reaching task to explore the contribution of efference copy to trajectory control. JDY and eight healthy controls reached without visual feedback to a target that either remained stationary or jumped to a second location after movement initiation. JDY consistently made hypermetric movements to the final target, exhibiting significant problems with amplitude control. Despite this amplitude control deficit, JDY's performance on jump trials showed that the angle of movement correction (angle between pre- and post-correction movement segments) was significantly correlated with the distance (but not time) of movement from start to turn point. These data suggest that despite an absence of proprioceptive and visual information regarding hand location, JDY derived information about movement distance that informed her movement correction on jump trials. The same type of information that permitted her to correct movement direction on-line, however, was not available for control of final arm position. We propose that efference copy can provide a consistent estimate of limb position that becomes less informative over the course of the movement. We discuss the implications of these data for current models of motor control.
先前对去传入神经受试者的研究表明，传出副本可用于更新肢体位置。然而，目前尚不清楚传出副本对肢体定位的贡献。我们检查了一位患有严重、长期感觉周围神经病感觉缺失的女性 JDY 在进行伸展任务时的表现，以探讨传出副本对轨迹控制的贡献。JDY 和 8 位健康对照者在没有视觉反馈的情况下伸手够向一个目标，该目标在运动开始后要么保持静止，要么跳到第二个位置。JDY 始终向最终目标进行超距运动，表现出明显的幅度控制问题。尽管存在幅度控制缺陷，但 JDY 在跳跃试验中的表现表明，运动校正角度（校正前后运动段之间的角度）与从起点到转弯点的运动距离（但不是时间）显著相关。这些数据表明，尽管 JDY 缺乏有关手部位置的本体感觉和视觉信息，但她可以从跳跃试验中获得关于运动距离的信息，从而进行运动校正。然而，对于最终手臂位置的控制，她无法获得允许其在线校正运动方向的相同类型的信息。我们提出，传出副本可以提供肢体位置的一致估计，随着运动的进行，其信息含量会降低。我们讨论了这些数据对当前运动控制模型的影响。
