引用

成熟的运动系统损伤导致轴突自发萌发，而不是轴突再生。了解轴突萌发的电路水平决定因素对损伤后修复电机电路以实现功能康复具有重要意义。竞争性相互作用在发育过程中形成了皮质脊髓束轴突的生长和退缩。竞争是否以及如何促进成熟脊髓运动回路的重组尚不清楚。为了研究这个问题，我们检查了在两种互补的本体感觉传入操作下皮质脊髓轴突的可塑性变化:(1)通过电刺激增强本体感觉传入活动;(2)通过背侧小根根切断术减少输入。实验在成年大鼠身上进行。电刺激产生本体感觉传入芽生，伴随显著的皮质脊髓轴突消退，内侧中间区胆碱能中间神经元和运动神经元上的C扣的皮质脊髓连接减少。相反，背侧根根切断术导致皮质脊髓连接显著增加，包括胆碱能中间神经元的连接;C钮扣密度相应增加。 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.,Neuroplasticity is limited in maturity, but it is promoted after injury. Axons of the major descending motor pathway for motor skills, the corticospinal tract (CST), sprout after brain or spinal cord injury. This contributes to spontaneous spinal motor circuit repair and partial motor recovery. Knowing the determinants that enhance this plasticity is critical for functional rehabilitation. Here we examine the remodeling of CST axons directed by sensory fibers. We found that the CST projection is regulated dynamically in maturity by the competitive, activity-dependent actions of sensory fibers. Knowledge of the properties of this competition enables prediction of the remodeling of CST connections and spinal circuits after injury and informs ways to engineer target-specific control of CST connections to promote recovery.