Song Weiguo, Martin John H
Department of Physiology, Pharmacology and Neuroscience, City University of New York School of Medicine, New York, New York; and.
Department of Physiology, Pharmacology and Neuroscience, City University of New York School of Medicine, New York, New York; and
J Neurophysiol. 2017 Mar 1;117(3):1143-1155. doi: 10.1152/jn.00584.2016. Epub 2016 Dec 28.
Spinal cord direct current stimulation (sDCS) has the potential for promoting motor function after injury through its modulatory actions on sensory processing, reflex functions, the motor cortex (M1) motor map, and motor output. Here we addressed systems-level mechanisms underlying sDCS neuromodulation of spinal circuits activated by M1 and peripheral forelimb electrical stimulation in anesthetized healthy rats. We determined the effects of cathodal and anodal sDCS (c- and a-sDCS) on local field potentials (LFP) and single-unit activity recorded at 32 sites simultaneously within the sixth cervical segment using a silicon multielectrode array. M1 stimulation produced distinctive dorsomedial and ventral LFP responses that showed polarity-dependent sDCS modulation. c-sDCS enhanced and a-sDCS depressed significantly ventral M1 responses; neither modulated dorsal responses significantly. Using evoked changes in β- and γ-oscillations to assay network function, c-sDCS enhanced and a-sDCS reduced oscillation power ventrally. c-sDCS increased and a-sDCS decreased background firing and firing synchrony of recorded pairs of single units. Peripheral stimulation produced a region-dependent response that showed polarity-dependent sDCS modulation. The dorsomedial LFP was unaffected by c-sDCS and weakly suppressed with a-sDCS. Peripheral-evoked unit responses showed limited polarity dependence. Our findings stress that ventral motor network behavior is enhanced by the neuromodulatory actions of c-sDCS. The combined actions of c-sDCS on M1-evoked neural responses and network behavior in the cervical spinal cord help explain the reported enhanced motor effects of this neuromodulation approach and inform the mechanisms of sDCS for promoting motor rehabilitation after spinal cord or brain injury. Spinal cord direct current stimulation (sDCS) modulates spinal functions and shows potential for neural rehabilitation after motor systems injury. Using a multichannel electrode array, we found that cathodal DCS enhanced, and anodal depressed, M1-evoked local field potentials, network oscillations, neuronal activity, and neuronal synchrony, especially in the ventral horn. With this new understanding, it is hoped that sDCS can be developed into a tunable spinal neuromodulatory tool for promoting function after brain or spinal injury.
脊髓直流电刺激（sDCS）具有通过对感觉处理、反射功能、运动皮层（M1）运动图谱和运动输出的调节作用来促进损伤后运动功能恢复的潜力。在此，我们研究了在麻醉的健康大鼠中，sDCS对由M1和外周前肢电刺激激活的脊髓回路进行神经调节的系统水平机制。我们使用硅多电极阵列，测定了阴极和阳极sDCS（c-sDCS和a-sDCS）对在第六颈椎节段内32个位点同时记录的局部场电位（LFP）和单单位活动的影响。M1刺激产生了独特的背内侧和腹侧LFP反应，这些反应表现出极性依赖性的sDCS调节。c-sDCS增强而a-sDCS显著抑制腹侧M1反应；两者均未对背侧反应产生显著调节作用。利用β和γ振荡的诱发变化来检测网络功能，c-sDCS增强而a-sDCS降低腹侧振荡功率。c-sDCS增加而a-sDCS降低记录的单单位对的背景放电和放电同步性。外周刺激产生了区域依赖性反应，该反应表现出极性依赖性的sDCS调节。背内侧LFP不受c-sDCS影响，而被a-sDCS微弱抑制。外周诱发的单位反应显示出有限的极性依赖性。我们的研究结果强调，c-sDCS的神经调节作用可增强腹侧运动网络行为。c-sDCS对M1诱发的神经反应和颈脊髓网络行为的联合作用有助于解释该神经调节方法所报道的增强运动效果，并为sDCS促进脊髓或脑损伤后运动康复的机制提供信息。脊髓直流电刺激（sDCS）可调节脊髓功能，并在运动系统损伤后显示出神经康复的潜力。使用多通道电极阵列，我们发现阴极DCS增强而阳极DCS抑制M1诱发的局部场电位、网络振荡、神经元活动和神经元同步性，尤其是在腹角。基于这一新认识，希望sDCS能够发展成为一种可调节的脊髓神经调节工具，以促进脑或脊髓损伤后的功能恢复。
