Paired motor cortex and cervical epidural electrical stimulation timed to converge in the spinal cord promotes lasting increases in motor responses.
Paired motor cortex and cervical epidural electrical stimulation timed to converge in the spinal cord promotes lasting increases in motor responses.
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DOI：
10.1113/jp274663
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发表时间：
2017-11-15
期刊：
影响因子：
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通讯作者：
Carmel JB
中科院分区：
文献类型：
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作者：
Mishra AM;Pal A;Gupta D;Carmel JB
配对运动皮质刺激和脊髓硬膜外刺激产生了运动皮质诱发电位的大量增强，如果它们在脊髓集中的时间。当脊髓电极置于背根入口区时，脊髓刺激对皮层诱发电位的调节最大。运动皮层和脊髓刺激的重复配对导致两个部位的诱发电位持续增加，但只有在刺激之间的时间是最佳的。配对刺激的即时和持久效应可能是由下行运动回路和大直径传入神经向颈脊髓共同中间神经元的收敛所介导的。神经回路的收敛性活动可以在它们的交叉点产生变化。配对电刺激的规则是最好的理解协议，刺激输入电路和他们的目标。我们采取了一种不同的方法，以下行运动通路和脊髓大直径传入神经的相互作用为目标。我们假设运动皮质和颈脊髓的配对刺激会通过它们的聚合来增强运动反应。我们在大鼠的运动皮层和颈脊髓背侧放置硬膜外电极；测量肱二头肌运动诱发电位（MEPs）。在低于诱发MEP阈值的强度下，脊髓硬膜外刺激可显著增强运动皮层诱发的MEP。增强主要依赖于脊髓刺激的时间和位置。当脊髓刺激与运动皮层刺激的下降波重合时，mep增加了一倍多。然后，我们测试了运动皮层和脊髓刺激重复配对的效果。重复配对引起皮质mep和脊髓兴奋性的强烈增强，在配对5分钟后持续长达1小时。另外的生理学实验支持成对刺激是由下行运动回路和大直径传入脊髓的收敛所介导的假说。该方案的巨大效应量以及在大鼠和人类之间被操纵的回路的守恒性使得中枢神经系统损伤后感觉运动功能的恢复值得追求。配对运动皮质刺激和脊髓硬膜外刺激产生了运动皮质诱发电位的大量增强，如果它们在脊髓集中的时间。当脊髓电极置于背根入口区时，脊髓刺激对皮层诱发电位的调节最大。运动皮层和脊髓刺激的重复配对导致两个部位的诱发电位持续增加，但只有在刺激之间的时间是最佳的。配对刺激的即时和持久效应可能是由下行运动回路和大直径传入神经向颈脊髓共同中间神经元的收敛所介导的。
Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord. The modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone. Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal. Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord. Convergent activity in neural circuits can generate changes at their intersection. The rules of paired electrical stimulation are best understood for protocols that stimulate input circuits and their targets. We took a different approach by targeting the interaction of descending motor pathways and large diameter afferents in the spinal cord. We hypothesized that pairing stimulation of motor cortex and cervical spinal cord would strengthen motor responses through their convergence. We placed epidural electrodes over motor cortex and the dorsal cervical spinal cord in rats; motor evoked potentials (MEPs) were measured from biceps. MEPs evoked from motor cortex were robustly augmented with spinal epidural stimulation delivered at an intensity below the threshold for provoking an MEP. Augmentation was critically dependent on the timing and position of spinal stimulation. When the spinal stimulation was timed to coincide with the descending volley from motor cortex stimulation, MEPs were more than doubled. We then tested the effect of repeated pairing of motor cortex and spinal stimulation. Repetitive pairing caused strong augmentation of cortical MEPs and spinal excitability that lasted up to an hour after just 5 min of pairing. Additional physiology experiments support the hypothesis that paired stimulation is mediated by convergence of descending motor circuits and large diameter afferents in the spinal cord. The large effect size of this protocol and the conservation of the circuits being manipulated between rats and humans makes it worth pursuing for recovery of sensorimotor function after injury to the central nervous system. Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord. The modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone. Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal. Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord.