Azim Eiman, Fink Andrew J P, Jessell Thomas M
Departments of Neuroscience and Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, New York 10032
Departments of Neuroscience and Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, New York 10032.
Cold Spring Harb Symp Quant Biol. 2014;79:81-92. doi: 10.1101/sqb.2014.79.024786. Epub 2015 Feb 19.
Skilled motor behavior emerges from interactions between efferent neural pathways that induce muscle contraction and feedback systems that report and refine movement. Two broad classes of feedback projections modify motor output, one from the periphery and a second that originates within the central nervous system. The mechanisms through which these pathways influence movement remain poorly understood, however. Here we discuss recent studies that delineate spinal circuitry that binds external and internal feedback pathways to forelimb motor behavior. A spinal presynaptic inhibitory circuit regulates the strength of external feedback, promoting limb stability during goal-directed reaching. A distinct excitatory propriospinal circuit conveys copies of motor commands to the cerebellum, establishing an internal feedback loop that rapidly modulates forelimb motor output. The behavioral consequences of manipulating these two circuits reveal distinct controls on motor performance and provide an initial insight into feedback strategies that underlie skilled forelimb movement.
熟练的运动行为源于诱导肌肉收缩的传出神经通路与报告和完善运动的反馈系统之间的相互作用。两类广泛的反馈投射会修改运动输出，一类来自外周，另一类起源于中枢神经系统。然而，这些通路影响运动的机制仍知之甚少。在这里，我们讨论了最近的研究，这些研究描绘了将外部和内部反馈通路与前肢运动行为联系起来的脊髓回路。一个脊髓突触前抑制回路调节外部反馈的强度，在目标导向的伸手过程中促进肢体稳定性。一个独特的兴奋性脊髓固有回路将运动指令的副本传递到小脑，建立一个内部反馈回路，该回路迅速调节前肢运动输出。操纵这两个回路的行为后果揭示了对运动表现的不同控制，并为熟练前肢运动背后的反馈策略提供了初步见解。
