Chen Yi, Chen Xiang Yang, Jakeman Lyn B, Schalk Gerwin, Stokes Bradford T, Wolpaw Jonathan R
Laboratory of Nervous System Disorders, Wadsworth Center, New York State Department of Health, State University of New York, Albany, New York 12201, USA.
J Neurosci. 2005 Jul 20;25(29):6898-906. doi: 10.1523/JNEUROSCI.1684-05.2005.
New and old motor skills can interfere with each other or interact in other ways. Because each skill entails a distributed pattern of activity-dependent plasticity, investigation of their interactions is facilitated by simple models. In a well characterized model of simple learning, rats and monkeys gradually change the size of the H-reflex, the electrical analog of the spinal stretch reflex. This study evaluates in normal rats the interactions of this new skill of H-reflex conditioning with the old well established skill of overground locomotion. In rats in which the soleus H-reflex elicited in the conditioning protocol (i.e., the conditioning H-reflex) had been decreased by down-conditioning, the H-reflexes elicited during the stance and swing phases of locomotion (i.e., the locomotor H-reflexes) were also smaller. Similarly, in rats in which the conditioning H-reflex had been increased by up-conditioning, the locomotor H-reflexes were also larger. Soleus H-reflex conditioning did not affect the duration, length, or right/left symmetry of the step cycle. However, the conditioned change in the stance H-reflex was positively correlated with change in the amplitude of the soleus locomotor burst, and the correlation was consistent with current estimates of the contribution of primary afferent input to the burst. Although H-reflex conditioning and locomotion did not interfere with each other, H-reflex conditioning did affect how locomotion was produced: it changed soleus burst amplitude and may have induced compensatory changes in the activity of other muscles. These results illustrate and clarify the subtlety and complexity of skill interactions. They also suggest that H-reflex conditioning might be used to improve the abnormal locomotion produced by spinal cord injury or other disorders of supraspinal control.
新的和旧的运动技能可能会相互干扰或以其他方式相互作用。由于每种技能都需要一种依赖活动的可塑性分布模式，因此简单的模型有助于对它们的相互作用进行研究。在一个特征明确的简单学习模型中，大鼠和猴子会逐渐改变H反射的大小，H反射是脊髓牵张反射的电模拟。本研究评估了正常大鼠中这种新的H反射条件反射技能与已确立的旧的地面行走技能之间的相互作用。在条件反射实验中通过下调使比目鱼肌H反射（即条件反射H反射）降低的大鼠中，在行走的站立和摆动阶段引出的H反射（即运动H反射）也较小。同样，在通过上调使条件反射H反射增加的大鼠中，运动H反射也较大。比目鱼肌H反射条件反射不影响步周期的持续时间、长度或左右对称性。然而，站立H反射的条件性变化与比目鱼肌运动爆发幅度的变化呈正相关，且这种相关性与目前对初级传入输入对爆发贡献的估计一致。虽然H反射条件反射和行走不会相互干扰，但H反射条件反射确实会影响行走的产生方式：它改变了比目鱼肌爆发幅度，并且可能诱导了其他肌肉活动的代偿性变化。这些结果说明了并阐明了技能相互作用的微妙性和复杂性。它们还表明，H反射条件反射可能用于改善脊髓损伤或其他脊髓上控制障碍所产生的异常行走。
