Abstract
The frequency, amplitude and time course of spontaneous excitatory junction potentials (SEJP) and their relationship to the time course and amplitude of evoked excitatory junction potentials (EJP) were examined. The frequency and amplitude of SEJP varied dramatically between cells. There was good correlation between their rise and decay times. The amplitude and time course of EJP also varied between cells. EJP with large amplitudes and fast time courses were recorded in cells with high SEJP frequencies. Active responses propagated only for very limited distances. The frequency of SEJP decreased after reserpine and 6-hydroxydopamine (6-OHDA) treatments, suggesting the SEJP were related to spontaneous release of noradrenaline [norepinephrine] from nerve terminals.