CERVO Brain Research Center, Laval University, Québec City, Québec G1J 2G3, Canada
CERVO Brain Research Center, Laval University, Québec City, Québec G1J 2G3, Canada.
J Neurosci. 2023 Jul 26;43(30):5521-5536. doi: 10.1523/JNEUROSCI.2089-22.2023. Epub 2023 Jul 3.
Animals interact with their environment through mechanically active, mobile sensors. The efficient use of these sensory organs implies the ability to track their position; otherwise, perceptual stability or prehension would be profoundly impeded. The nervous system may keep track of the position of a sensorimotor organ via two complementary feedback mechanisms-peripheral reafference (external, sensory feedback) and efference copy (internal feedback). Yet, the potential contributions of these mechanisms remain largely unexplored. By training male rats to place one of their vibrissae within a predetermined angular range without contact, a task that depends on knowledge of vibrissa position relative to their face, we found that peripheral reafference is not required. The presence of motor cortex is not required either, except in the absence of peripheral reafference to maintain motor stability. Finally, the red nucleus, which receives descending inputs from motor cortex and cerebellum and projects to facial motoneurons, is critically involved in the execution of the vibrissa positioning task. All told, our results point toward the existence of an internal model that requires either peripheral reafference or motor cortex to optimally drive voluntary motion. How does an animal know where a mechanically active, mobile sensor lies relative to its body? We address this basic question in sensorimotor integration using the motion of the vibrissae in rats. We show that rats can learn to reliably position their vibrissae in the absence of sensory feedback or in the absence of motor cortex. Yet, when both sensory feedback and motor cortex are absent, motor precision is degraded. This suggests the existence of an internal model able to operate in closed- and open-loop modes, requiring either motor cortex or sensory feedback to maintain motor stability.
动物通过机械活跃、可移动的传感器与环境相互作用。这些感觉器官的有效利用意味着它们能够跟踪自己的位置；否则，感知稳定性或抓握能力将受到严重阻碍。神经系统可能通过两种互补的反馈机制——外周重反射（外部、感觉反馈）和传出副本（内部反馈）来跟踪感觉运动器官的位置。然而，这些机制的潜在贡献在很大程度上仍未得到探索。通过训练雄性大鼠将其胡须中的一根置于预定的角度范围内而不接触，这是一项依赖于胡须相对于脸部位置的知识的任务，我们发现外周重反射不是必需的。运动皮层的存在也不是必需的，除非没有外周重反射来维持运动稳定性。最后，红核（从运动皮层和小脑接收下行输入，并投射到面部运动神经元）对于执行胡须定位任务至关重要。总之，我们的结果表明存在一种内部模型，它需要外周重反射或运动皮层来最佳地驱动自主运动。动物如何知道一个机械活跃、可移动的传感器相对于其身体的位置？我们在使用大鼠的触须运动来解决感觉运动整合中的这个基本问题。我们表明，大鼠可以在没有感觉反馈或没有运动皮层的情况下可靠地定位它们的触须。然而，当感觉反馈和运动皮层都不存在时，运动精度就会降低。这表明存在一种内部模型，能够在闭环和开环模式下运行，需要运动皮层或感觉反馈来维持运动稳定性。
