Cuadra Cristian, Wojnicz Wiktoria, Kozinc Ziga, Latash Mark L
Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA; Escuela Kinesiología, Facultad de Ciencias de la Rehabilitación, Universidad Andres Bello, Calle Quillota 980, Viña del Mar, Chile.
Department of Mechanics and Mechatronics, Mechanical Engineering Faculty, Gdansk University of Technology, Gdansk, Poland.
Neuroscience. 2020 Jun 15;437:34-44. doi: 10.1016/j.neuroscience.2020.04.023. Epub 2020 Apr 24.
We tested several predictions of the theory of motor control with spatial referent coordinates related to effects of muscle coactivation on force production and perception. In particular, we predicted that subjects would produce unintentional force increase by finger flexors and be unaware of this force increase. Healthy subjects performed steady force production task in isometric conditions with visual feedback on the force level. They coactivated muscles of the arm trying to keep the force constant in the absence of visual feedback. This led to a consistent force increase not perceived by the subjects as reflected by their verbal reports. In contrast, when asked to match the force with the contralateral hand, adequate force matching was observed. Using the "inverse piano" apparatus confirmed no change in the referent coordinate of the fingers and an increase in its apparent stiffness. The results confirm the earlier hypothesis on the reciprocal command being hierarchically higher than the coactivation command. The observations suggest that verbal reports and force matching use different neural mechanisms of force perception; the former are dominated by sense of effort, which reflects primarily the magnitude of the reciprocal command. There were only minor differences between the dominant and non-dominant hands, likely reflecting the faster unintentional drifts of control variables in the dominant hand.
我们用与肌肉共同激活对力量产生和感知的影响相关的空间参照坐标，测试了运动控制理论的几个预测。具体而言，我们预测受试者的手指屈肌会产生无意的力量增加，并且他们不会意识到这种力量增加。健康受试者在等长条件下执行稳定力量产生任务，并在力量水平上有视觉反馈。他们共同激活手臂肌肉，试图在没有视觉反馈的情况下保持力量恒定。这导致了受试者未察觉到的持续力量增加，这从他们的口头报告中得到了反映。相比之下，当要求他们用对侧手匹配力量时，观察到了适当的力量匹配。使用“反向钢琴”装置证实手指的参照坐标没有变化，但其表观刚度增加。结果证实了早期关于交互指令在层次上高于共同激活指令的假设。这些观察结果表明，口头报告和力量匹配使用不同的力量感知神经机制；前者主要由努力感主导，这主要反映了交互指令的大小。优势手和非优势手之间只有微小差异，这可能反映了优势手中控制变量更快的无意漂移。
