Motor commands for the arm and hand generally arise from the contralateral motor cortex, where most of the relevant corticospinal tract originates. However, the ipsilateral motor cortex shows activity related to arm movement despite the lack of direct connections. The extent to which the activity related to ipsilateral movement is independent from that related to contralateral movement is unclear based on conflicting conclusions in prior work. Here we investigate bilateral arm and hand movement tasks completed by two human subjects with intracortical microelectrode arrays implanted in the left hand and arm area of the motor cortex. Neural activity was recorded while they attempted to perform arm and hand movements in a virtual environment. This enabled us to quantify the strength and independence of motor cortical activity related to continuous movements of each arm. We also investigated the subjects’ ability to control both arms through a brain–computer interface. Through a number of experiments, we found that ipsilateral arm movement was represented independently of, but more weakly than, contralateral arm movement. However, the representation of grasping was correlated between the two hands. This difference between hand and arm representation was unexpected and poses new questions about the different ways the motor cortex controls the hands and arms.

中文翻译：

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运动皮层对同侧和对侧手臂运动有独立的表示，但对抓握有相关的表示。

手臂和手的运动命令通常来自对侧运动皮层，其中大部分相关的皮质脊髓束起源于那里。然而，尽管缺乏直接联系，同侧运动皮层显示出与手臂运动相关的活动。基于先前工作中相互矛盾的结论，与同侧运动相关的活动独立于与对侧运动相关的活动的程度尚不清楚。在这里，我们研究了由两个人类受试者完成的双侧手臂和手部运动任务，其中皮层内微电极阵列植入运动皮层的左手和手臂区域。当他们试图在虚拟环境中进行手臂和手部运动时，神经活动被记录下来。这使我们能够量化与每只手臂的连续运动相关的运动皮层活动的强度和独立性。我们还调查了受试者通过脑机接口控制双臂的能力。通过大量实验，我们发现同侧手臂运动独立于对侧手臂运动，但比对侧手臂运动更弱。然而，抓握的表现在两只手之间是相关的。手和手臂表示之间的这种差异是出乎意料的，并且对运动皮层控制手和手臂的不同方式提出了新的问题。但比对侧手臂运动更弱。然而，抓握的表现在两只手之间是相关的。手和手臂表示之间的这种差异是出乎意料的，并且对运动皮层控制手和手臂的不同方式提出了新的问题。但比对侧手臂运动更弱。然而，抓握的表现在两只手之间是相关的。手和手臂表示之间的这种差异是出乎意料的，并且对运动皮层控制手和手臂的不同方式提出了新的问题。