Department of Neuroscience and Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; email:
Annu Rev Neurosci. 2019 Jul 8;42:315-335. doi: 10.1146/annurev-neuro-070918-050436. Epub 2019 Apr 2.
Hand dexterity has uniquely developed in higher primates and is thought to rely on the direct corticomotoneuronal (CM) pathway. Recent studies have shown that rodents and carnivores lack the direct CM pathway but can control certain levels of dexterous hand movements through various indirect CM pathways. Some homologous pathways also exist in higher primates, and among them, propriospinal (PrS) neurons in the mid-cervical segments (C3-C4) are significantly involved in hand dexterity. When the direct CM pathway was lesioned caudal to the PrS and transmission of cortical commands to hand motoneurons via the PrS neurons remained intact, dexterous hand movements could be significantly recovered. This recovery model was intensively studied, and it was found that, in addition to the compensation by the PrS neurons, a large-scale reorganization in the bilateral cortical motor-related areas and mesolimbic structures contributed to recovery. Future therapeutic strategies should target these multihierarchical areas.
手的灵巧性在高等灵长类动物中得到了独特的发展，据认为它依赖于直接皮质运动神经元（CM）通路。最近的研究表明，啮齿动物和食肉动物缺乏直接的 CM 通路，但可以通过各种间接的 CM 通路来控制一定程度的灵巧手部运动。在高等灵长类动物中也存在一些同源通路，其中中颈段（C3-C4）的固有脊髓（PrS）神经元对手的灵巧性有显著的影响。当直接的 CM 通路在 PrS 下游受损，而皮质命令通过 PrS 神经元向手部运动神经元的传递仍然完好时，灵巧的手部运动可以得到显著的恢复。这种恢复模型得到了深入研究，结果发现，除了 PrS 神经元的代偿作用外，双侧皮质运动相关区域和中脑边缘结构的大规模重组也有助于恢复。未来的治疗策略应该针对这些多层次的区域。
