[Synchronization of discharges of human motor units during voluntary muscle contractions and tonic vibration reflex].
Cross-correlograms (CCGs) of action potentials of single motor unit (MU) pairs of soleus, triceps br. and 1 interosseus dors muscles were plotted. The CCGs of 21 pairs from 126 pairs studied during voluntary muscle contraction revealed peaks at a zero point, the peak width being less than or equal to 5 ms (short-term synchronization). During the tonic vibration reflex of the soleus and triceps br. muscles there were 12 synchronized MU pairs from 86 studied pairs. The CCGs of MU 1 and 2 interosseus dors. muscles revealed the synchronization in 4 pairs from 10 studied pairs. The "strength" of synchronization in all MU pairs was low: usually no more than 6% of all impulses coincided above the probability of accidental coincidences. The short-term synchronization is, presumably, a result of common input to different motoneurons from branches of the last-order premotoneuron nerve fibres. The long-term synchronization of MUs was revealed in the CCGs. This synchronization is supposedly caused by the muscle fatigue during the experiment.
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D000200:Action Potentials / Q000502:physiology; D006801:Humans; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D014732:Vibration
Sinkhronizatsiia razriadov dvigatel'nykh edinits cheloveka pri proizvol'nom sokrashchenii myshtsy i tonicheskom vibratsionnom reflekse.