It is generally assumed that the main function of the corticospinal tract (CST) is to convey motor commands to bulbar or spinal motoneurons. Yet the CST has also been shown to modulate sensory signals at their entry point in the spinal cord through primary afferent depolarization (PAD). By sequentially investigating different routes of corticofugal pathways through electrophysiological recordings and an intersectional viral strategy, we here demonstrate that motor and sensory modulation commands in mice belong to segregated paths within the CST. Sensory modulation is executed exclusively by the CST via a population of lumbar interneurons located in the deep dorsal horn. In contrast, the cortex conveys the motor command via a relay in the upper spinal cord or supraspinal motor centers. At lumbar level, the main role of the CST is thus the modulation of sensory inputs, which is an essential component of the selective tuning of sensory feedback used to ensure well-coordinated and skilled movement.

中文翻译：

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皮质脊髓束主要调节小鼠腰椎的感觉输入

一般认为皮质脊髓束 (CST) 的主要功能是向延髓或脊髓运动神经元传递运动指令。然而，CST 也被证明可以通过初级传入去极化 (PAD) 在脊髓的入口点调节感觉信号。通过电生理记录和交叉病毒策略依次研究皮质真菌通路的不同途径，我们在这里证明小鼠的运动和感觉调制命令属于 CST 内的隔离路径。感觉调制完全由 CST 通过位于深背角的一组腰椎中间神经元执行。相比之下，皮层通过上脊髓或脊髓上运动中枢中的中继传递运动命令。在腰椎层面，