Descending command neurons instruct spinal networks to execute basic locomotor functions, such as gait and speed. The command functions for gait and speed are symmetric, implying that a separate unknown system directs asymmetric movements, including the ability to move left or right. In the present study, we report that Chx10-lineage reticulospinal neurons act to control the direction of locomotor movements in mammals. Chx10 neurons exhibit mainly ipsilateral projection, and their selective unilateral activation causes ipsilateral turning movements in freely moving mice. Unilateral inhibition of Chx10 neurons causes contralateral turning movements. Paired left-right motor recordings identified distinct mechanisms for directional movements mediated via limb and axial spinal circuits. Finally, we identify sensorimotor brain regions that project on to Chx10 reticulospinal neurons, and demonstrate that their unilateral activation can impart left-right directional commands. Together these data identify the descending motor system that commands left-right locomotor asymmetries in mammals.

中文翻译：

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脑干神经元，控制哺乳动物的运动不对称。

下降命令神经元指示脊髓网络执行基本的运动功能，例如步态和速度。步态和速度的命令功能是对称的，这意味着一个单独的未知系统会引导不对称运动，包括向左或向右移动的能力。在本研究中，我们报告Chx10谱系网状脊髓神经元的作用是控制哺乳动物运动的方向。Chx10神经元主要表现出同侧投射，并且它们的选择性单侧激活在自由移动的小鼠中引起同侧转弯运动。Chx10神经元的单侧抑制会导致对侧转向运动。成对的左右运动记录确定了通过肢体和轴向脊髓回路介导的定向运动的不同机制。最后，我们确定投射到Chx10网状脊髓神经元的感觉运动脑区域，并证明它们的单侧激活可以传递左右方向的命令。这些数据共同确定了在哺乳动物中控制左右运动不对称的下降运动系统。