Schieppati M, Nardone A, Musazzi M
Hum Neurobiol. 1986;5(1):59-66.
The inhibition of the H-reflex of the Soleus (Sol) muscle that takes place during and after voluntary release of Sol muscle has been attributed to presynaptic inhibition of autogenetic spindle afferences. In the present study, the time-relationship between onset of H-reflex depression and termination of Sol contraction was investigated to ascertain whether the reflex inhibition is linked to the command to release, or whether it is an accompanying phenomenon connected to changes in the neural outflow from the periphery. A parallel investigation was carried out on the temporal characteristics of the facilitation of the H-reflex that precedes onset of Sol contraction, in an attempt to point at the different functional organization of the two motor tasks. Voluntary releases from a bilateral isometric plantar torque, or bilateral plantar flexions, were performed in response to an acoustic stimulus, in a reaction time (RT) situation. The intervals from the starting signal to complete termination, or to beginning, of the Sol EMG were measured. The H-reflex was evoked at random during the tasks in one leg and its amplitude was referred in time to the end, or to the onset, of the EMG recorded from the contralateral Sol muscle. The RTs of the termination of Sol EMG had an average duration of about 100 ms, being some 20 ms shorter than those of the onset of EMG. In the release-task, the H-reflex amplitude was higher than that of the controls during the holding phase, and started to decrease about 20 ms before the cessation of the EMG.(ABSTRACT TRUNCATED AT 250 WORDS)
比目鱼肌（Sol）在自主放松期间及之后出现的H反射抑制，被认为是由于自生性肌梭传入纤维的突触前抑制。在本研究中，对H反射抑制开始与Sol收缩终止之间的时间关系进行了研究，以确定反射抑制是与放松指令相关，还是与外周神经传出变化相关的伴随现象。对Sol收缩开始之前H反射易化的时间特征进行了平行研究，以试图指出这两种运动任务的不同功能组织。在反应时间（RT）情境下，根据声音刺激，进行双侧等长足底扭矩或双侧足底屈曲的自主放松。测量从起始信号到Sol肌电图完全终止或开始的时间间隔。在任务过程中，随机刺激一条腿诱发H反射，并将其幅度与对侧Sol肌记录的肌电图结束或开始时间相关联。Sol肌电图终止的反应时间平均约为100毫秒，比肌电图开始的反应时间短约20毫秒。在放松任务中，在保持阶段H反射幅度高于对照组，并且在肌电图停止前约20毫秒开始下降。（摘要截短于250字）
