Figure 4.

Terminals originating from an individual axon but contacting different cell types display different PPR. (A) Voltage and current traces: action potentials triggered by intracellular current pulses in a presynaptic CA3 pyramidal cell (1) evoked unitary EPSCs in a monosynaptically connected alveus-oriens interneuron (2) and a subsequently recorded pyramidal cell (3). The traces are composed of seven superimposed sweeps. (B) Histogram: Summary graph (n = 3). PPR is p2/p1. (In, interneurons; Pyr, pyramidal cells) (C) Micrograph of a typical Lucifer yellow filled oriens/alveus interneuron in culture. The horizontally extending dendrites run parallel to the stratum pyramidale (Upper) and to the alveus (Lower). (Bar = 60 μm.)