首页> 外文期刊>The Journal of Neuroscience: The Official Journal of the Society for Neuroscience >Competition with Primary Sensory Afferents Drives Remodeling of Corticospinal Axons in Mature Spinal Motor Circuits
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Competition with Primary Sensory Afferents Drives Remodeling of Corticospinal Axons in Mature Spinal Motor Circuits

机译:与主要感觉传入的竞争驱动成熟脊髓运动回路中皮质脊髓轴突的重塑。

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Injury to the mature motor system drives significant spontaneous axonal sprouting instead of axon regeneration. Knowing the circuit-level determinants of axonal sprouting is important for repairing motor circuits after injury to achieve functional rehabilitation. Competitive interactions are known to shape corticospinal tract axon outgrowth and withdrawal during development. Whether and how competition contributes to reorganization of mature spinal motor circuits is unclear. To study this question, we examined plastic changes in corticospinal axons in response to two complementary proprioceptive afferent manipulations: (1) enhancing proprioceptive afferents activity by electrical stimulation; or (2) diminishing their input by dorsal rootlet rhizotomy. Experiments were conducted in adult rats. Electrical stimulation produced proprioceptive afferent sprouting that was accompanied by significant corticospinal axon withdrawal and a decrease in corticospinal connections on cholinergic interneurons in the medial intermediate zone and C boutons on motoneurons. In contrast, dorsal rootlet rhizotomy led to a significant increase in corticospinal connections, including those on cholinergic interneurons; C bouton density increased correspondingly. Motor cortex-evoked muscle potentials showed parallel changes to those of corticospinal axons, suggesting that reciprocal corticospinal axon changes are functional. Using the two complementary models, we showed that competitive interactions between proprioceptive and corticospinal axons are an important determinant in the organization of mature corticospinal axons and spinal motor circuits. The activity- and synaptic space-dependent properties of the competition enables prediction of the remodeling of spared corticospinal connection and spinal motor circuits after injury and informs the target-specific control of corticospinal connections to promote functional recovery.
机译:对成熟运动系统的伤害会导致明显的自发性轴突发芽,而不是轴突再生。知道轴突出芽的电路水平决定因素对于受伤后修复运动电路以实现功能恢复很重要。已知竞争相互作用会影响发育过程中皮质脊髓束突突的生长和退缩。竞争是否以及如何促进成熟的脊髓运动回路的重组尚不清楚。为了研究这个问题,我们研究了皮质脊髓轴突的塑性变化,以响应两种互补的本体感受传入操作:(1)通过电刺激增强本体感受传入活动;或(2)通过背根根切开术减少其输入。实验是在成年大鼠中进行的。电刺激产生本体感受传入发芽,伴随着显着的皮质脊髓轴突撤回,中间中间区胆碱能中枢神经元和运动神经元C boutons上的皮质脊髓连接减少。相反,背根根切开术导致皮质脊髓连接的显着增加,包括胆碱能神经元上的连接。胸肉密度相应增加。运动皮质诱发的肌肉电位显示出与皮质脊髓突触轴突平行的变化,这表明相互的皮质脊髓突触轴突具有功能。使用两个互补模型,我们表明本体感受性和皮质脊髓轴突之间的竞争性相互作用是组织成熟的皮质脊髓轴突和脊髓运动回路的重要决定因素。比赛的活动和突触空间依赖性特性可预测受伤后剩余的皮质脊髓连接和脊髓运动回路的重塑,并告知皮质脊髓连接的靶标特异性控制以促进功能恢复。

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