[Study of participation of reflex mechanisms in postinhibitory rebound by analyzing the activity of individual human motor units].
The mechanism of postinhibitory rebound after maximal and submaximal for M-response nerve stimulation was studied on firing motor units of hand muscles (m. abd. poll. br., m. abd. dig. min.) and leg muscles (m. soleus, m. rect. fem.) of healthy people. The poststimulus histograms and changes in an interspike interval duration were compared with time course of a twitch mechanogram. In all muscles under strong evoked twitch the only cause of the burst following the silent period was the synchronous motoneuron escape from inhibition. Under strong muscle twitch a true motoneuron facilitation was revealed. It is suggested that this is a reflex response to muscle extending in muscle relaxation phase after induced twitching. In leg muscles the revealed facilitation had a latency of spinal monosynaptic reflex with regard to the supposed moment of the burst in spindle afferents. In hand muscles (with H-reflex known to be suppressed in a normal man) the adequate activation of spindles during muscle relaxation caused facilitation only with the latency of polysynaptic reflex. These data are in accordance with a hypothesis on supraspinal presynaptic inhibition of monosynaptic action of spindle afferents in motoneurons of some human muscles.
D004558:Electric Stimulation; D006801:Humans; D009046:Motor Neurons / Q000502:physiology*; D009470:Muscle Spindles / Q000502:physiology*; D009132:Muscles / Q000294:innervation*; D009433:Neural Inhibition; D010525:Peripheral Nerves / Q000502:physiology; D012018:Reflex / Q000502:physiology*; D012023:Reflex, Monosynaptic; D013116:Spinal Cord / Q000502:physiology*
Issledovanie uchastiia reflektornykh mekhanizmov v posttormoznoĭ otdache s pomoshch'iu analiza aktivnosti otdel'nykh dvigatel'nykh edinits cheloveka.