Effect of the synchronization of the discharges of single motor units for the formation of the summated electromyogram.
The monosynaptic electromyographic reflex (EMG) response to muscle stretching represents a synchronized discharge from the single motor units (MUs). The role of this synchronization, taking into account the effect of the subsequent voluntary activity, has been investigated by calculating the probabilities for the appearance of impulse from a single MU for consecutive 10 ms time intervals. Experimental data on the firing of the single MUs under stationary conditions and before the front of the summated EMG for m. triceps surae are used. The results obtained are compared with the experimental data on the interaction of the stretch reflex and the voluntary movement in response to the stretch. It is shown that the synchronization in itself cannot explain the later responses in the EMG, which are with latencies longer than the latency of the monosynaptic reflex, but shorter than the reaction time of the subsequent voluntary activity.
D004576:Electromyography; D004594:Electrophysiology; D006801:Humans; D008433:Mathematics; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000294:innervation