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首页> 外文期刊>Progress in brain research >Neural control of on-line guidance of hand reaching movements.
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Neural control of on-line guidance of hand reaching movements.

机译：在线控制手到达动作的神经控制。

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Orienting one's gaze towards a peripheral target is usually composed of a hypometric primary saccade followed by a secondary 'corrective saccade' triggered automatically (without conscious perception) by the retinal error at the end of the primary saccade and characterised by a short latency. Due to visual suppression during the saccade, the artificial introduction of a random small target jump during that short period remains undetected and triggers after the end of the primary saccade a normal 'corrective saccade'. As a result this procedure simulates an error in the planning of the primary saccade. On the other hand optimum hand pointing (trade-off between movement time and accuracy) is considered classically to involve a natural parallel initiation of saccade and hand response based on a poor peripheral retinal location, and a further amendment of the hand motor response based on the retinal error provided by the simultaneous vision of target and hand during the movement home phase. To test the hypothesis that the retinal feedback at the end of the primary saccade is used to update the visual target position and amend the ongoing hand motor response, we developed a paradigm involving both an optimum hand pointing and an undetected random target perturbation during the orienting saccade. In order to show that the amendments were controlled by a loop comparing the perceived target location with the dynamic hand position signal, vision of the limb was removed at movement onset. Results showed that the movement was smoothly monitored on-line without additional time processing demands. This functional property of flexibility of the ongoing hand motor response, was generalized from movement extent to movement direction. The undetectability of the perturbation at a conscious level was not a prerequisite for motor flexibility, which was further shown to depend on a critical phase of the limb movement beyond which the latter was no longer amendable, even when the limb was visible. The hand pointing flexibility was further generalised from pointing to the more complex hand reaching and grasping process. It was shown that the flexibility of both the transport and the grasp components were closely coupled. A careful analysis of the data suggested the controlled variable to be the general posture of the upper limb, reaching Bernstein's intuitions about redundancy reduction in skeletomotor systems with degrees of freedom in excess. A kinematics study of the motor flexibility of reaching and grasping in a patient with a bilateral optic ataxia favoured the idea of a posterior parietal cortex involvement in the error processing underlying motor flexibility, reaching the same conclusions as other recent studies using either Positron Emission Tomography or Transcranial Magnetic Stimulation.
机译：将视线对准外围目标通常由低视度主扫视，然后由主扫视结束时的视网膜错误自动触发（无意识知觉）的次要“矫正扫视”。由于扫视过程中的视觉抑制，在短时间内没有人为引入随机的小目标跳跃仍然未被发现，并且在主扫视结束后触发了正常的“校正扫视”。结果，该过程模拟了主扫视的规划错误。另一方面，经典的最佳手法指向（运动时间和准确性之间的折衷）通常被认为涉及扫视和手部反应的自然平行起始，这是由于周围视网膜位置较差而引起的，而手部运动反应的进一步修正是基于运动归位阶段目标和手的同时视觉提供的视网膜误差。为了检验以下假设：在主扫视结束时使用视网膜反馈来更新视觉目标位置并修改正在进行的手部运动反应，我们开发了一种范式，该范式既包括最佳的指向性，又包括定向过程中未检测到的随机目标扰动扫视。为了显示修正是通过一个循环来控制的，该循环将感知的目标位置与动态手位置信号进行比较，在运动开始时去除了肢体的视力。结果表明，该机芯可以在线进行流畅的监控，而无需额外的时间处理要求。从运动程度到运动方向，概括了正在进行的手运动响应的灵活性的这种功能特性。在意识水平上无法检测到摄动并不是运动灵活性的先决条件，这进一步表明，运动依赖于肢体运动的一个关键阶段，超过该阶段，即使肢体可见，后者也不再可修改。从指向更复杂的手到达和抓握过程开始，进一步扩展了手的灵活性。结果表明，运输部件和抓地部件的柔韧性紧密相连。对数据的仔细分析表明，控制变量是上肢的总体姿势，达到了伯恩斯坦关于自由度过大的骨骼运动系统冗余减少的直觉。运动学研究对双侧视神经共济失调患者达到和掌握的运动灵活性的看法支持后顶叶皮层参与运动柔韧性背后的错误处理的想法，得出的结论与最近使用正电子发射断层扫描或正电子发射断层扫描技术进行的其他研究相同。经颅磁刺激。

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