It is generally believed that task-dependent control of body configuration ("posture") is achieved by adjusting voluntary motor activity and transcortical "long-latency" reflexes. Spinal monosynaptic circuits are thought not to be engaged in such task-level control. Similarly, being in a state of motor learning has been strongly associated only with an upregulation of feedback responses at transcortical latencies and beyond. In two separate experiments, the current study examined the task-dependent modulation of stretch reflexes by perturbing the hand of human subjects while they were waiting for a "Go" signal to move at the different stages of a classic kinematic learning task (visuomotor rotation). Although the subjects had to resist all haptic perturbations equally across task stages, the study leveraged that task-dependent feedback controllers may already be "loaded" at the movement anticipation stage. In addition to an upregulation of reflex gains during early exposure to the visual distortion, I found a relative inhibition of reflex responses in the "washout" stage (sensory realignment state). For more distal muscles (brachioradialis) this inhibition also extended to the monosynaptic reflex response ("R1"). Moreover, these R1 gains reflected individual motor learning performance in the visuomotor task. The results demonstrate that the system's "control policy" in visuomotor adaptation can also include inhibition of proprioceptive reflexes, and that aspects of this policy can affect monosynaptic spinal circuits. The latter finding suggests a novel form of state-related control, probably realized by independent control of fusimotor neurons, through which segmental circuits can tune to higher-level features of a sensorimotor task. (PsycINFO Database Record

中文翻译：

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依赖于任务的脊柱和经皮拉伸反射的调制与运动学习率有关。

通常认为，通过调节自主运动活动和经皮层的“长潜伏期”反射，可以实现任务依赖的身体形态控制（“姿势”）。脊柱单突触回路被认为不参与这种任务级控制。类似地，处于运动学习状态仅与经皮层潜伏期及以后的反馈反应的上调强烈相关。在两个单独的实验中，本研究通过在等待“ Go”信号在经典运动学习任务（视觉运动旋转）的不同阶段运动时扰动人类受试者的手，研究了依赖于任务的拉伸反射调制。 。尽管受试者在整个任务阶段必须同样抵抗所有触觉干扰，该研究利用了与任务相关的反馈控制器可能已在运动预期阶段“加载”的功能。除了早期暴露于视觉畸变期间反射增益的上调外，我发现在“冲洗”阶段（感觉重新排列状态），反射反应受到了相对抑制。对于更多的远端肌肉（臂radi肌），这种抑制作用还扩展到单突触反射反应（“ R1”）。此外，这些R1的获得反映了视觉运动任务中个体运动学习的表现。结果表明，该系统在视觉运动适应中的“控制策略”还可以包括对本体感受反射的抑制，并且该策略的各个方面都可以影响单突触性脊髓回路。后一个发现表明国家相关控制的一种新颖形式，可能是通过对融合运动神经元的独立控制来实现的，分段神经可以通过这些独立控制来调节感觉运动任务的高级功能。（PsycINFO数据库记录