Brunelli Giorgio, von Wild Klaus
Foundation for research on Spinal Cord Lesions, Brescia, Italy.
J Korean Neurosurg Soc. 2009 Jul;46(1):1-4. doi: 10.3340/jkns.2009.46.1.1. Epub 2009 Jul 31.
To report an unsuspected adaptive plasticity of single upper motor neurons and of primary motor cortex found after microsurgical connection of the spinal cord with peripheral nerve via grafts in paraplegics and focussed discussion of the reviewed literature.
The research aimed at making paraplegics walk again, after 20 years of experimental surgery in animals. Amongst other things, animal experiments demonstrated the alteration of the motor endplates receptors from cholinergic to glutamatergic induced by connection with upper motor neurons. The same paradigm was successfully performed in paraplegic humans. The nerve grafts were put into the ventral-lateral spinal tract randomly, without possibility of choosing the axons coming from different areas of the motor cortex.
The patient became able to selectively activate the re-innervated muscles she wanted without concurrent activities of other muscles connected with the same cortical areas.
Authors believe that unlike in nerve or tendon transfers, where the whole cortical area corresponding to the transfer changes its function a phenomenon that we call "brain plasticity by areas", in our paradigm due to the direct connection of upper motor neurons with different peripheral nerves and muscles via nerve grafts motor learning occurs based on adaptive neuronal plasticity so that simultaneous contractions of other muscles are prevented. We propose to call it adaptive functional "plasticity by single neurons". We speculate that this phenomenon is due to the simultaneous activation of neurons spread in different cortical areas for a given specific movement, whilst the other neurons of the same areas connected with peripheral nerves of different muscles are not activated at the same time. Why different neurons of the same area fire at different times according to different voluntary demands remains to be discovered. We are committed to solve this enigma hereafter.
报告在截瘫患者中通过移植将脊髓与周围神经进行显微外科连接后发现的单个上运动神经元和初级运动皮层意外的适应性可塑性，并对相关文献进行集中讨论。
经过20年的动物实验手术，该研究旨在使截瘫患者重新行走。动物实验表明，与上运动神经元连接可导致运动终板受体从胆碱能转变为谷氨酸能。同样的模式在截瘫患者中也成功实施。将神经移植物随机植入脊髓腹外侧束，无法选择来自运动皮层不同区域的轴突。
患者能够选择性地激活她想要的重新支配的肌肉，而不会同时激活与同一皮层区域相连的其他肌肉。
作者认为，与神经或肌腱转移不同，在神经或肌腱转移中，与转移相对应的整个皮层区域会改变其功能，我们将这种现象称为“按区域的脑可塑性”，而在我们的模式中，由于上运动神经元通过神经移植物与不同的周围神经和肌肉直接连接，运动学习基于适应性神经元可塑性发生，从而防止其他肌肉同时收缩。我们建议将其称为适应性功能性“单个神经元可塑性”。我们推测，这种现象是由于在给定的特定运动中，分布在不同皮层区域的神经元同时被激活，而同一区域与不同肌肉周围神经相连的其他神经元不会同时被激活。同一区域的不同神经元为何根据不同的自愿需求在不同时间放电仍有待发现。我们致力于在此后解开这个谜团。
