Gerasimenko Yury, Sayenko Dimitry, Gad Parag, Kozesnik Justin, Moshonkina Tatiana, Grishin Aleksandr, Pukhov Aleksandr, Moiseev Sergey, Gorodnichev Ruslan, Selionov Victor, Kozlovskaya Inessa, Edgerton V Reggie
Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia.
Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, United States.
Front Physiol. 2018 Sep 19;9:1196. doi: 10.3389/fphys.2018.01196. eCollection 2018.
Neuronal control of stepping movement in healthy human is based on integration between brain, spinal neuronal networks, and sensory signals. It is generally recognized that there are continuously occurring adjustments in the physiological states of supraspinal centers during all routines movements. For example, visual as well as all other sources of information regarding the subject's environment. These multimodal inputs to the brain normally play an important role in providing a feedforward source of control. We propose that the brain routinely uses these continuously updated assessments of the environment to provide additional feedforward messages to the spinal networks, which provides a synergistic feedforwardness for the brain and spinal cord. We tested this hypothesis in 8 non-injured individuals placed in gravity neutral position with the lower limbs extended beyond the edge of the table, but supported vertically, to facilitate rhythmic stepping. The experiment was performed while visualizing on the monitor a stick figure mimicking bilateral stepping or being motionless. Non-invasive electrical stimulation was used to neuromodulate a wide range of excitabilities of the lumbosacral spinal segments that would trigger rhythmic stepping movements. We observed that at the same intensity level of transcutaneous electrical spinal cord stimulation (tSCS), the presence or absence of visualizing a stepping-like movement of a stick figure immediately initiated or terminated the tSCS-induced rhythmic stepping motion, respectively. We also demonstrated that during both voluntary and imagined stepping, the motor potentials in leg muscles were facilitated when evoked cortically, using transcranial magnetic stimulation (TMS), and inhibited when evoked spinally, using tSCS. These data suggest that the ongoing assessment of the environment within the supraspinal centers that play a role in planning a movement can routinely modulate the physiological state of spinal networks that further facilitates a synergistic neuromodulation of the brain and spinal cord in preparing for movements.
健康人类的踏步运动的神经元控制基于大脑、脊髓神经元网络和感觉信号之间的整合。人们普遍认识到，在所有日常运动过程中，脊髓上中枢的生理状态会不断发生调整。例如，视觉以及关于受试者环境的所有其他信息来源。这些大脑的多模式输入通常在提供前馈控制源方面发挥重要作用。我们提出，大脑通常利用这些对环境的不断更新的评估，向脊髓网络提供额外的前馈信息，这为大脑和脊髓提供了协同前馈作用。我们在8名未受伤的个体中测试了这一假设，这些个体处于重力中性位置，下肢伸展到桌子边缘之外，但垂直支撑，以促进有节奏的踏步。实验是在监视器上可视化一个模仿双侧踏步或静止不动的简笔画人物的同时进行的。使用非侵入性电刺激对腰骶脊髓节段的广泛兴奋性进行神经调节，以触发有节奏的踏步运动。我们观察到，在相同强度水平的经皮脊髓电刺激（tSCS）下，可视化简笔画人物的踏步样运动的存在或不存在分别立即启动或终止了tSCS诱导的有节奏的踏步运动。我们还证明，在自愿和想象踏步过程中，当使用经颅磁刺激（TMS）皮层诱发时，腿部肌肉的运动电位得到促进，而当使用tSCS脊髓诱发时则受到抑制。这些数据表明，在运动计划中起作用的脊髓上中枢内对环境的持续评估可以常规调节脊髓网络的生理状态，这进一步促进了大脑和脊髓在运动准备中的协同神经调节。
