Following alpha-latrotoxin application to cerebellar slices, bursts of
miniature IPSCs (mIPSCs) were observed in interneurons of the molecul
ar layer. Within bursts, mIPSCs had homogeneous amplitudes with a narr
ow Gaussian distribution. Analysis of successive event amplitudes reve
aled an interaction between consecutive IPSCs, indicating that bursts
originate at single release sites. A mean receptor occupancy of 76% wa
s calculated. IPSCs within a burst were analyzed using nonstationary n
oise analysis. The results indicate that individual release sites diff
er in the number, unitary conductance, and peak opening probability of
their postsynaptic channels. In addition, the IPSC decay kinetics wer
e very different among release sites. Finally, a significant correlati
on was found between several pairs of single site synaptic parameters.