Center for Information and Neural Networks, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho Nishiku, Kobe Hyogo 651-2492, Japan.
J Neurophysiol. 2012 Jan;107(1):126-33. doi: 10.1152/jn.00735.2010. Epub 2011 Oct 12.
Efficient control of reciprocal activation and cocontraction of the muscles are critical to perform skillful actions with suitable force and impedance. However, it remains unclear how the brain controls force and impedance while recruiting the same set of muscles as actuators. Does control take place at the single muscle level leading to force and impedance, or are there higher-order centers dedicated to controlling force and impedance? We addressed this question using functional MRI during voluntary isometric wrist contractions with online electromyogram feedback. Comparison of the brain activity between the conditions requiring control of either wrist torque or cocontraction demonstrates that blood oxygen level-dependent activity in the caudo-dorsal premotor cortex (PMd) correlates well with torque, whereas the activity in the ventral premotor cortex (PMv) correlates well with the level of cocontraction. This suggests distinct roles of the PMd and PMv in the voluntary control of reciprocal activation and cocontraction of muscles, respectively.
有效地控制肌肉的交互激活和共同收缩对于用适当的力和阻抗执行熟练的动作至关重要。然而，目前尚不清楚大脑在招募相同的肌肉作为执行器时如何控制力和阻抗。控制是发生在导致力和阻抗的单个肌肉水平上，还是存在专门用于控制力和阻抗的更高阶中心？我们使用功能磁共振成像（fMRI）在自愿等长腕部收缩期间进行了研究，同时在线肌电图反馈。比较需要控制腕部扭矩或共同收缩的条件下的大脑活动表明，依赖血氧水平的尾-背侧前运动皮层（PMd）的活动与扭矩密切相关，而腹侧前运动皮层（PMv）的活动与共同收缩的程度密切相关。这表明 PMd 和 PMv 在自愿控制肌肉的交互激活和共同收缩方面分别发挥着不同的作用。
