Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, Rm. 140, Los Angles, CA 90089, USA.
Exp Brain Res. 2012 Jan;216(2):191-201. doi: 10.1007/s00221-011-2928-0. Epub 2011 Nov 10.
Simple movements can be seen as building blocks for complex action sequences, and neural control of an action sequence can be expected to preserve some control features of its constituent blocks. It was previously found that during single-joint elbow movements to a single target, the proprioceptive feedback control is initially suppressed, and we tested this feedback suppression in a two-segment sequence during which subjects momentarily slowed down at an intermediate target at a 30° distance (first segment) and then immediately moved another 30° to the final target (second segment). Either the first or second segment was unexpectedly perturbed; the latency of the earliest response to the perturbation in the muscle surface electromyogram was analyzed. The perturbations were delivered either at the onset of each segment or about 0.1 s later. We found that in both segments, the response latency to the late perturbation was shorter than the latency to the early perturbation, which suggests that the proprioceptive feedback control is suppressed in the beginning of each segment. Next, we determined the latency of the response to unexpected perturbations in 30° movements to a single target. We found that the response latency was not significantly different in the movement to a single target and in each segment in the sequence. This result suggests that the initial suppression of the proprioceptive feedback control in movements to single targets is preserved in movements through intermediate targets and supports the idea of modular organization of neural control of movement sequences.
简单的动作可以被视为复杂动作序列的组成部分，而对动作序列的神经控制预计会保留其组成部分的一些控制特征。先前已经发现，在单个关节向单个目标进行肘部运动时，本体感觉反馈控制最初会被抑制，我们在两段序列中测试了这种反馈抑制，在此期间，受试者在中间目标（距离 30°）处短暂减速（第一段），然后立即向最终目标（第二段）再移动 30°。第一段或第二段会意外受到干扰；分析了在肌肉表面肌电图中对干扰的最早反应的潜伏期。在每个段的开始或大约 0.1 秒后，施加了干扰。我们发现，在两段中，对后期干扰的反应潜伏期都短于对早期干扰的潜伏期，这表明在每个段的开始时本体感觉反馈控制被抑制。接下来，我们确定了对单个目标的 30°运动中意外干扰的反应潜伏期。我们发现，对单个目标的运动和序列中每个段的运动的反应潜伏期没有显著差异。这一结果表明，对单个目标运动中本体感觉反馈控制的初始抑制在通过中间目标的运动中得到了保留，并支持运动序列神经控制模块化组织的观点。
