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自愿肢体运动所涉及的感觉运动整合的时间动态。

Temporal dynamics of the sensorimotor convergence underlying voluntary limb movement.

机构信息

Department of Developmental Physiology, National Institute for Physiological Sciences, National Institute of Natural Sciences, Okazaki, Aichi 444-8585, Japan.

Department of Integrated Neuroanatomy and Neuroimaging, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.

出版信息

Proc Natl Acad Sci U S A. 2022 Nov 29;119(48):e2208353119. doi: 10.1073/pnas.2208353119. Epub 2022 Nov 21.

Abstract

Descending motor drive and somatosensory feedback play important roles in modulating muscle activity. Numerous studies have characterized the organization of neuronal connectivity in which descending motor pathways and somatosensory afferents converge on spinal motor neurons as a final common pathway. However, how inputs from these two pathways are integrated into spinal motor neurons to generate muscle activity during actual motor behavior is unknown. Here, we simultaneously recorded activity in the motor cortices (MCx), somatosensory afferent neurons, and forelimb muscles in monkeys performing reaching and grasping movements. We constructed a linear model to explain the instantaneous muscle activity using the activity of MCx (descending input) and peripheral afferents (afferent input). Decomposition of the reconstructed muscle activity into each subcomponent indicated that muscle activity before movement onset could first be explained by descending input from mainly the primary motor cortex and muscle activity after movement onset by both descending and afferent inputs. Descending input had a facilitative effect on all muscles, whereas afferent input had a facilitative or suppressive effect on each muscle. Such antagonistic effects of afferent input can be explained by reciprocal effects of the spinal reflex. These results suggest that descending input contributes to the initiation of limb movement, and this initial movement subsequently affects muscle activity via the spinal reflex in conjunction with the continuous descending input. Thus, spinal motor neurons are subjected to temporally organized modulation by direct activation through the descending pathway and the lagged action of the spinal reflex during voluntary limb movement.

摘要

下行运动驱动和躯体感觉反馈在调节肌肉活动中起着重要作用。许多研究已经描述了神经元连接的组织,其中下行运动通路和躯体感觉传入在脊髓运动神经元上汇聚为最终的共同途径。然而,在实际运动行为中,这些两条途径的输入是如何整合到脊髓运动神经元中以产生肌肉活动的仍然未知。在这里,我们在猴子执行伸手和抓握运动时同时记录了运动皮层(MCx)、躯体感觉传入神经元和前肢肌肉的活动。我们构建了一个线性模型,使用 MCx(下行输入)和外周传入(传入输入)的活动来解释即时肌肉活动。将重建的肌肉活动分解为每个子成分表明,运动前的肌肉活动首先可以用主要来自初级运动皮层的下行输入来解释,而运动后的肌肉活动可以用下行输入和传入输入共同解释。下行输入对所有肌肉都有促进作用,而传入输入对每块肌肉都有促进或抑制作用。传入输入的这种拮抗作用可以用脊髓反射的交互作用来解释。这些结果表明,下行输入有助于肢体运动的启动,并且这种初始运动随后通过与连续的下行输入相结合的脊髓反射影响肌肉活动。因此,脊髓运动神经元受到通过下行途径的直接激活和在自愿肢体运动期间脊髓反射的滞后作用的时间组织调节。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/75ae/9860324/09ea0b3ae36e/pnas.2208353119fig01.jpg

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