Fig. 5.

Frequency of spontaneous neurotransmitter release is higher, and amplitude of quantal events is larger, in mutant animals. A, Traces of membrane potential showing spontaneous transmitter release (miniature potentials) in mutants and controls. Calibration bar: 2 mV, 1 sec. The downward deflections in the mutant trace are 1 mV calibration pulses; ∼4 sec of data are shown.B, Summary of frequency of spontaneous miniature potentials from 10 mutant and 8 control cells. C, Amplitude histogram of spontaneous miniature potentials recorded from mutant and control animals. These histograms were constructed from data recorded from four mutant (244 events) and four control (222 events) cells. The data are grouped into 0.3 mV bins.