Islam Md Anamul, Pulverenti Timothy S, Knikou Maria
Klab4Recovery Research Laboratory, Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, United States.
PhD Program in Biology and Collaborative Neuroscience Program, Graduate Center of the City University of New York and College of Staten Island, New York, NY, United States.
Front Hum Neurosci. 2021 Feb 18;15:620414. doi: 10.3389/fnhum.2021.620414. eCollection 2021.
This study investigated the neuromodulatory effects of transspinal stimulation on soleus H-reflex excitability and electromyographic (EMG) activity during stepping in humans with and without spinal cord injury (SCI). Thirteen able-bodied adults and 5 individuals with SCI participated in the study. EMG activity from both legs was determined for steps without, during, and after a single-pulse or pulse train transspinal stimulation delivered during stepping randomly at different phases of the step cycle. The soleus H-reflex was recorded in both subject groups under control conditions and following single-pulse transspinal stimulation at an individualized exactly similar positive and negative conditioning-test interval. The EMG activity was decreased in both subject groups at the steps during transspinal stimulation, while intralimb and interlimb coordination were altered only in SCI subjects. At the steps immediately after transspinal stimulation, the physiological phase-dependent EMG modulation pattern remained unaffected in able-bodied subjects. The conditioned soleus H-reflex was depressed throughout the step cycle in both subject groups. Transspinal stimulation modulated depolarization of motoneurons over multiple segments, limb coordination, and soleus H-reflex excitability during assisted stepping. The soleus H-reflex depression may be the result of complex spinal inhibitory interneuronal circuits activated by transspinal stimulation and collision between orthodromic and antidromic volleys in the peripheral mixed nerve. The soleus H-reflex depression by transspinal stimulation suggests a potential application for normalization of spinal reflex excitability after SCI.
本研究调查了经脊髓刺激对脊髓损伤（SCI）患者和非脊髓损伤患者在步行过程中比目鱼肌H反射兴奋性和肌电图（EMG）活动的神经调节作用。13名健全成年人和5名脊髓损伤患者参与了该研究。在步行过程中，于步周期的不同阶段随机施加单脉冲或脉冲串经脊髓刺激，分别测定刺激前、刺激期间和刺激后双腿的EMG活动。在对照条件下以及在个体化的完全相似的正负条件 - 测试间隔下进行单脉冲经脊髓刺激后，记录两组受试者的比目鱼肌H反射。经脊髓刺激期间，两组受试者在步行时的EMG活动均降低，而仅脊髓损伤受试者的肢体内部和肢体间协调性发生改变。在经脊髓刺激后的即刻步行时，健全受试者的生理相位依赖性EMG调制模式未受影响。在整个步周期中，两组受试者的条件性比目鱼肌H反射均受到抑制。经脊髓刺激在辅助步行过程中调节了多个节段运动神经元的去极化、肢体协调性和比目鱼肌H反射兴奋性。比目鱼肌H反射抑制可能是经脊髓刺激激活复杂的脊髓抑制性中间神经元回路以及外周混合神经中顺向和逆向冲动碰撞的结果。经脊髓刺激导致的比目鱼肌H反射抑制提示其在脊髓损伤后脊髓反射兴奋性正常化方面具有潜在应用价值。
