THE EFFECT OF PERCUTANEOUS MOTOR CORTEX STIMULATION ON H REFLEXES IN MUSCLES OF THE ARM AND LEG IN INTACT MAN
THE EFFECT OF PERCUTANEOUS MOTOR CORTEX STIMULATION ON H REFLEXES IN MUSCLES OF THE ARM AND LEG IN INTACT MAN
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DOI：
10.1113/jphysiol.1986.sp016190
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发表时间：
1986-08-01
影响因子：
5.5
通讯作者：
ROTHWELL, JC
中科院分区：
文献类型：
--
作者：
COWAN, JMA;DAY, BL;ROTHWELL, JC
通过头皮电极对大脑进行电刺激的技术已经被用于激活正常人的皮质脊髓通路。当被测试的肌肉完全放松时，刺激的强度被调整到低于引起直接肌电图反应所需的阈值。用H反射（单突触）测试测量脊髓兴奋性的变化。通过这种方式，发现即使在没有直接肌肉反应的情况下，阈下头皮刺激也可以产生下行皮质脊髓齐射。脊髓兴奋性的变化的时间过程中进行了评估，唤起测试H反射在不同的时间间隔相对于头皮刺激。在手腕和手指屈肌的七个科目，一个单一的阈下头皮休克产生的H反射，平均持续2.5毫秒的初始峰值便利。结束的初始便利的标志是返回的H反射向基础水平，并在一个场合由坦率的抑制。结果表明，单突触兴奋性突触后电位（e.p.s.p.s.）并被随后到达的双突触抑制性突触后电位（i.p.s.p.s.）截断。最初的便利化之后是第二阶段的便利化的H反射。第二阶段比第一阶段更弱，更易变，持续时间更长（从5到20 ms）。对H反射产生影响所需的头皮刺激强度的阈值对于促进的第一和第二阶段是相同的。几种可能的解释进行了讨论的机制负责后期和持久的促进。在两个主题的手腕和手指伸肌进行了研究。H-反射的变化的时间过程是类似的屈肌，除了最初的促进随后由一个坦率的抑制在两个科目。在一个主题鱼际肌肉和胫骨前肌进行了研究，并表现出类似的手腕和手指屈肌肌肉。在7名受试者中研究了对比目鱼肌H反射的影响。在其中五名受试者中，与研究的其他肌肉相反，最初的事件是H反射的抑制。这种抑制也可以在平均整流表面肌电图（e.m.g.）记录当头皮刺激时，在比目鱼肌的弱自愿激活。这表明，比目鱼肌的单突触兴奋性皮质脊髓投射是弱的短潜伏期抑制性事件相比。比目鱼肌的主要兴奋性投射可能主要是多突触的。
The technique of electrical stimulation of the brain via scalp electrodes has been used to activate corticospinal pathways in intact man. The intensity of stimulation was adjusted to be below the threshold necessary to evoke a direct electromyographic response when the muscles being tested were totally relaxed. Changes in spinal cord excitability were measured using H-reflex (monosynaptic) testng. By this means it was found that subthreshold scalp stimulation can produce a descending corticospinal volley even in the absence of a direct muscle response. The time course of changes in spinal cord excitability was evaluated by evoking test H reflexes at different intervals relative to the scalp stimulus. In wrist and finger flexor muscles of seven subjects, a single subthreshold scalp shock produced an initial peak facilitation of the H reflex which on average lasted for 2.5 ms. The end of the initial facilitation was marked by a return of the H reflex towards basal levels and on one occasion by a frank inhibition. It is suggested that the initial facilitation is produced by arrival at the motoneurones of monosynaptic excitatory post-synaptic potentials (e.p.s.p.s.) and is truncated by the subsequent arrival of disynaptic inhibitory post-synaptic potentials (i.p.s.p.s.). The initial facilitation was followed by a second phase of facilitation of the H reflex. The second phase was weaker, more variable and longer lasting (from 5 to 20 ms) than the first phase. The threshold of scalp stimulus intensity required to produce an effect on the H reflex was the same for the first and second phases of facilitation. Several possible explanations are discussed for the mechanism responsible for the late and long-lasting facilitation. In two subjects wrist and finger extensor muscles were studied. The time course of H-reflex changes was similar to that of the flexors except that the initial facilitation was followed by a frank inhibition in both subjects. In one subject thenar muscles and tibialis anterior were studied and behaved similarly to wrist and finger flexor muscles. Effects on the soleus H reflex was studied in seven subjects. In five of these subjects, in contrast to the other muscles studied, the initial event was an inhibition of the H reflex. This inhibition also could be seen preceding the usual period of facilitation in averaged rectified surface electromyogram (e.m.g.) records when scalp-stimuli were given during weak voluntary activation of soleus. It is suggested that for soleus the monosynaptic excitatory corticospinal projection is weak in comparison with short-latency inhibitory events. The dominant excitatory projection to soleus is likely to be largely polysynaptic.