Ueno Satoko, Yamaguchi Reona, Isa Kaoru, Kawasaki Toshinari, Mitsuhashi Masahiro, Kobayashi Kenta, Takahashi Jun, Isa Tadashi
Department of Neuroscience, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan.
J Comp Neurol. 2024 Dec;532(12):e70007. doi: 10.1002/cne.70007.
During recovery following spinal cord injury in the macaque, the sensorimotor cortex on the same side as the injury (ipsilesional, unaffected) becomes activated and plays a role in guiding movements of the affected hand. Effective regulation of these movements by the ipsilesional sensorimotor cortex would depend not only on its ability to send motor commands directly to target muscles but also on coordinated functioning with higher-level motor planning systems such as the cortico-basal ganglia and cortico-cerebellar loops. In this study, using anterograde viral tracers, we analyzed the axonal trajectories of corticofugal fibers from the contralesional (affected) primary motor cortex (M1) at the brainstem level in two macaque monkeys with sub-hemisection spinal cord injury at the mid-cervical level. They showed considerable recovery of grasping movements after injury. We found an increase in axonal projections from the contralesional M1 to the contralateral putamen, ipsilateral lateral reticular nucleus, and contralateral pontine nucleus compared to projections from the ipsilesional (unaffected) M1. We propose that these increased projections from the contralesional M1 to the striatum and precerebellar nuclei on the nondominant side may function to recruit the ipsilesional M1 through the cortico-basal ganglia and cortico-cerebellar loops to control hand movements on the affected side during recovery.
在猕猴脊髓损伤后的恢复过程中，损伤同侧（损伤侧，未受影响）的感觉运动皮层会被激活，并在引导患侧手部运动中发挥作用。损伤侧感觉运动皮层对这些运动的有效调节不仅取决于其直接向目标肌肉发送运动指令的能力，还取决于与更高层次的运动规划系统（如皮质-基底神经节和皮质-小脑环路）的协同功能。在本研究中，我们使用顺行病毒示踪剂，在两只中颈段半横断脊髓损伤的猕猴中，分析了脑干水平上来自对侧（受影响）初级运动皮层（M1）的皮质下行纤维的轴突轨迹。它们在损伤后抓握运动有相当程度的恢复。我们发现，与来自同侧（未受影响）M1的投射相比，对侧M1向对侧壳核、同侧外侧网状核和对侧脑桥核的轴突投射增加。我们提出，在恢复过程中，对侧M1向非优势侧纹状体和小脑前核的这些增加的投射可能通过皮质-基底神经节和皮质-小脑环路来募集损伤侧M1，以控制患侧的手部运动。
