| Abstract: | Hump-shaped distortion of motor nerve response, resembling spontaneous or single quanta in amplitude and time course were, observed at a temperature of 20°C, produced by stimulating this nerve during experiments on preparations of frog sartorius and cutaneous pectoral muscle involving focal extracellular recording. Having performed statistical analysis, the possibility could be excluded of this effect representing superposition of spontaneous over-evoked signals and the hypothesis could be put forward that it results from relatively unsynchronized release of separate quanta which go to make up a multiquantal response. This hypothesis would appear to be confirmed by clear-cut correlation between the distribution of synaptic delays in unitary response (when quantal content is low) and those observed in asynchronous response (when quantal content is high). Polymodal type distribution of synaptic delay is shown to be common to both cases. It is deduced that both asynchronous response and the discrete nature of variations in synaptic delay are standard features in the mechanisms of transmitter release.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 346–354, May–June, 1986. |
