2026-02-12 国立精神・神経医療研究センター,玉川大学
.jpg "なぜヒトの手はこんなに器用? 古い神経回路と新しい神経回路が役割分担して 柔軟さと安定性を両立させていることを発見")
図1 精密な手指運動を制御する二つの神経回路
<関連情報>
- https://www.ncnp.go.jp/topics/detail.php?@uid=NUUUjAzrwUvRfGp7
- https://www.science.org/doi/10.1126/sciadv.aea1184
霊長類の巧緻な手指運動は機能的に異なる二つの運動前神経システムによって制御されている Primate dexterous hand movements are controlled by functionally distinct premotoneuronal systems
Tomohiko Takei, Tomomichi Oya, and Kazuhiko Seki
Science Advances Published:11 Feb 2026
DOI:https://doi.org/10.1126/sciadv.aea1184
Abstract
Dexterous hand movements are uniquely developed in primates and indispensable for their daily activities. Traditionally, they were thought to depend primarily on the evolutionarily “newer” direct corticomotoneuronal (CM) pathway. However, recent studies suggest that the “older” indirect corticospinal pathways, mediated by spinal premotor interneurons (PreM-INs), also contribute, highlighting the need to clarify their functional differences. Here, we recorded neuronal activity from PreM-INs and CM cells in macaques during a precision grip task to compare their roles in generating hand muscle activity. Our results show that PreM-INs exert stronger facilitation across a broader set of muscles, promoting synergistic coactivation, whereas CM cells provide more selective facilitation, enabling control of relatively individual muscles. Decomposition analysis further revealed that these systems correspond to different control modes—synergy-based and individual-based control—balancing stability and flexibility. These findings redefine our understanding of primate dexterous hand control as emerging from the cooperative integration of evolutionarily distinct premotoneuronal systems.
