Selionov V A, Ivanenko Y P, Solopova I A, Gurfinkel V S
Laboratory of Neuromotor of Motor Control, Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia.
J Neurophysiol. 2009 Jun;101(6):2847-58. doi: 10.1152/jn.90895.2008. Epub 2009 Apr 1.
Air-stepping can be used as a model for investigating rhythmogenesis and its interaction with sensory input. Here we show that it is possible to entrain involuntary rhythmic movement patterns in healthy humans by using different kinds of stimulation techniques. The subjects lay on their sides with one or both legs suspended, allowing low-friction horizontal rotation of the limb joints. To evoke involuntary stepping of the suspended leg, either we used continuous muscle vibration, electrical stimulation of the superficial peroneal or sural nerves, the Jendrassik maneuver, or we exploited the postcontraction state of neuronal networks (Kohnstamm phenomenon). The common feature across all stimulations was that they were tonic. Air-stepping could be elicited by most techniques in about 50% of subjects and involved prominent movements at the hip and the knee joint (approximately 40-70 degrees). Typically, however, the ankle joint was not involved. Minimal loading forces (4-25 N) applied constantly to the sole (using a long elastic cord) induced noticeable (approximately 5-20 degrees) ankle-joint-angle movements. The aftereffect of a voluntary long-lasting (30-s) contraction in the leg muscles featured alternating rhythmic leg movements that lasted for about 20-40 s, corresponding roughly to a typical duration of the postcontraction activity in static conditions. The Jendrassik maneuver per se did not evoke air-stepping. Nevertheless, it significantly prolonged rhythmic leg movements initiated manually by an experimenter or by a short (5-s) period of muscle vibration. Air-stepping of one leg could be evoked in both forward and backward directions with frequent spontaneous transitions, whereas involuntary alternating two-legged movements were more stable (no transitions). The hypothetical role of tonic influences, contact forces, and bilateral coordination in rhythmogenesis is discussed. The results overall demonstrated that nonspecific tonic drive may cause air-stepping and the characteristics and stability of the evoked pattern depended on the sensory input.
空中踏步可作为研究节律产生及其与感觉输入相互作用的模型。在此我们表明，通过使用不同类型的刺激技术，在健康人类中诱发出非自主节律性运动模式是可能的。受试者侧卧，一条腿或两条腿悬空，使肢体关节能够进行低摩擦的水平旋转。为了诱发悬空腿的非自主踏步，我们要么使用持续的肌肉振动、对腓浅神经或腓肠神经进行电刺激、让受试者做耶德热西克动作，要么利用神经网络的收缩后状态（柯恩斯塔姆现象）。所有刺激的共同特征是它们都是持续性的。大多数技术能在约50%的受试者中诱发出空中踏步，且涉及髋部和膝关节的显著运动（约40 - 70度）。然而，通常踝关节并不参与。持续对脚底施加最小负荷力（4 - 25牛）（使用一根长弹性绳）会引起明显的（约5 - 20度）踝关节角度运动。腿部肌肉自愿进行长时间（30秒）收缩的后效应表现为交替的节律性腿部运动，持续约20 - 40秒，大致对应于静态条件下收缩后活动的典型持续时间。耶德热西克动作本身并不会诱发空中踏步。然而，它显著延长了由实验者手动发起或由短时间（5秒）肌肉振动引发的节律性腿部运动。单腿的空中踏步可以在向前和向后两个方向诱发，且频繁出现自发转换，而不自主的双腿交替运动则更稳定（无转换）。文中讨论了持续性影响、接触力和双侧协调在节律产生中的假设作用。总体结果表明，非特异性的持续性驱动可能导致空中踏步，且诱发模式的特征和稳定性取决于感觉输入。
