改变神经通路治疗脑损伤后上肢功能障碍中健侧大脑皮层新生功能区运动控制机制的研究

Central nervous system injury often left severe limb dysfunction. It is difficult to recover the function of the paralyzed limb. Our group proposed a new strategy which let healthy cerebral hemisphere control the paralyzed upper limb through cross-neck C7-C7 nerve transfer. The motor function of the paralyzed upper limb was improved significantly after the cross-neck C7-C7 nerve transfer. Moreover, Functional imaging and optogenetic experiments showed that a new functional areas emerged in the M1 area of the contralateral motor cortex, accompanying functional recovery of the paralyzed upper limb. However, retrograde tracing with PRV showed that neurons within contralateral M2 and S1 area also appears to innervate paralyzed upper limb, in addition to the contralateral M1 area, which indicated the paralyzed upper limb is controlled by M1, M2 and S1 area together. But the mechanism of M1, M2 and S1 area for controlling upper limb is not clear. In this study, rabies virus will be used to make neurons in the heathy cerebral cortex which control paralyzed upper limb specifically express light- sensitive protein (hChR2-EYFP or eNpHR3.0). Activating or inactivating M1, M2 and S1 areas with optogenetic techniques, the movement and EMG of the upper limbs will be record, as well as the influence on fine tasks also will be assessed, through which we will reveal the different roles of the contralateral M1, M2 and S1 area in motor control, and explain the motor control mechanism of the new functional areas emerged in the healthy cerebral hemisphere.

中枢神经系统损伤常遗留偏瘫等严重的肢体功能障碍，而对瘫痪肢体功能的恢复十分困难。课题组提出了通过周围神经交叉移位建立健存半脑支配瘫痪肢体的新策略。通过颈7神经交叉移位治疗，患者瘫痪上肢的运动功能可明显恢复。进一步研究证实在健侧皮层M1区出现支配瘫痪上肢的新功能区。而动物逆行示踪实验发现，新功能区不仅在M1区，健侧皮层的M2及S1区也有大量支配瘫痪上肢的神经元。这提示瘫痪上肢运动功能可能是由M1、M2及S1区共同支配的，但对新功能区运动控制的机制还不清楚。本课题拟用一侧脑外伤后健侧颈7神经移位的小鼠模型，应用示踪病毒使健侧大脑皮层支配瘫痪上肢的椎体神经元特异性表达光敏蛋白，再通过光遗传学技术分别对M1、M2及S1区进行兴奋或抑制，同步记录和评估对双侧上肢运动和执行精细任务的影响，揭示健侧皮层M1、M2及S1区新生功能区在运动控制中的不同作用，阐释健侧皮层新生功能区运动控制的机制。

一侧脑损伤后偏瘫肢体功能修复是临床上面临的重大挑战，课题组原创提出通过左右颈七神经交叉移位术（CC7）利用健侧大脑半球支配瘫痪上肢，以修复患肢运动功能的新策略。但神经移位后健侧半球对上肢运动控制的机制还不清楚。本课题通过构建一侧脑损伤后左右C7神经交叉移位（TBI+CC7）的小鼠模型，运用神经示踪、光遗传学、电生理学和行为学等手段揭示了左右C7神经交叉移位后健侧大脑皮层控制两侧上肢运动功能的主要皮质脊髓投射环路，并证实其在健侧皮层控制同侧瘫痪上肢精细的技能性运动中发挥重要作用。这一研究为进一步促进左右C7神经交叉移位后瘫痪上肢功能康复的研究提供了理论支持和干预靶点。此外，我们通过PRV神经示踪明确了支配一侧臂丛上干、中干和下干的皮质脊髓神经元（CSN）在大脑皮层M1、M2、S1及S2等多个脑区的空间分布特征，以及支配不同臂丛神经干的CSN在各脑区内的组织模式。这一研究填补了对支配神经干的CSN在大脑皮层空间分布和组织模式的认知，并为解释左右C7神经交叉移位后瘫痪上肢的运动控制和功能恢复的机制，以及进一步开发利用左右C7神经交叉移位的研究提供了理论支持。另外，我们改进了小鼠左右C7神经交叉移位的手术方式，可使两侧移位的神经直接吻合，大大缩短神经移位后上肢运动功能修复的时间，因此也可缩短TBI+CC7小鼠模型研究的实验周期，为后续的相关动物研究提供极大便利。

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