Currents evoked from a nucleated patch, recorded in the presence of extracellular magnesium (1 mM) and glycine (10 μM). L-Glutamate (1 mM) was applied in pulses of 1, 2, 10 and 100 ms at holding potentials of both +60 and -60 mV. The top trace represents the duration of the agonist application. Note the similarity in time course of the inward and outward current, indicating a lack of an NMDA-mediated component. Each trace is the average of three sweeps. Inset, plot of the average rise time of evoked glutamatergic synaptic currents against the average decay time constant in 31 cells; membrane potential, -70 mV, ▪. For comparison a Gaussian distribution of the mean evoked synaptic decay time constant (2·60 ± 1·01 ms, mean ±s.d.) and lines representing both the deactivation time constant (1·77 ± 0·21 ms, n= 10) and desensitization time constant (4·01 ± 0·85 ms, n= 9) are superimposed on the graph.