Contradictory hypotheses regarding the nature of synaptic transmission
in the CNS have arisen from indirect methods of quantal analysis. In
this study, we directly count the quanta released following nerve stim
ulation to examine synaptic transmission at a fast glutamatergic synap
se in the mammalian auditory brainstem. Our results demonstrate the re
lationship between spontaneous and nerve-evoked synaptic events, indic
ate that asynchronous transmitter release governs the time course of e
voked transmission, and show that the stochastic quantal release proce
ss, as originally proposed at the neuromuscular junction, is highly co
nserved at this central synapse.