Moerchen Victoria A, Gruben Kreg G
Department of Human Movement Science, University of Wisconsin-Milwaukee, Milwaukee, WI 53201-0413, USA.
Neurocase. 2006 Oct;12(5):300-6. doi: 10.1080/13554790601126039.
Afferent contributions to the coordination of thumb and index finger forces during non-lift pinch were studied using an anesthetization case study design. Two subjects, one performing with and without digital anesthetization and one with intact sensation, produced dynamic pinch forces against a stable object, with and without visual feedback. Error corrections were less frequent post-anesthetization, and the cross correlation between digit forces was lower when sensation was removed. However, this decrease in cross correlation between digit forces seemed to reflect a loss in the magnitude of tightly coupled error corrections when sensation was removed, rather than more frequent deviations of force magnitude between the digit forces. Force-time output without visual feedback lacked these error corrections, and the correlation between digit forces remained high, irrespective of sensory status. Additionally, with vision occluded, the time rate of force change did not vary in a gradual manner as would be expected from a neural representation of a sinusoidal target, but was instead marked by sudden abrupt reversals of force rate of change, invariant of somatosensory status. The coupling of digit forces and rates of force change during non-lift pinch appear to be controlled primarily with feedforward mechanisms, where the lack of proprioceptive feedback does not seem to disrupt this coupling.
采用麻醉案例研究设计，研究了在非提起捏取过程中传入神经对拇指和示指力量协调的贡献。两名受试者，一名在手指麻醉和未麻醉状态下进行操作，另一名感觉正常，在有和没有视觉反馈的情况下，对稳定物体施加动态捏力。麻醉后错误校正的频率降低，去除感觉后手指力量之间的互相关性降低。然而，手指力量之间互相关性的这种降低似乎反映了去除感觉时紧密耦合的错误校正幅度的损失，而不是手指力量之间力量幅度更频繁的偏差。没有视觉反馈时的力-时间输出缺乏这些错误校正，并且手指力量之间的相关性仍然很高，与感觉状态无关。此外，在视觉被遮挡的情况下，力变化的时间速率并没有像正弦目标的神经表征所预期的那样逐渐变化，而是以力变化速率的突然急剧反转标记，与体感状态无关。在非提起捏取过程中，手指力量和力变化速率的耦合似乎主要由前馈机制控制，其中本体感觉反馈的缺乏似乎不会破坏这种耦合。
