Figure 4.

Representative AII responses to RB output. A, During a paired RB–AII recording, the voltage-clamped RB was depolarized with a waveform designed to mimic a light flash-evoked voltage response. This elicited a very small, slow presynaptic Ca current (i) and evoked exocytosis that was recorded as a postsynaptic current in a voltage-clamped AII (single responses in ii; average responses in iii). B, When the same AII was recorded in the current-clamp configuration, evoked EPSPs were observed (single responses in ii; average responses in iii). Note that spikelets are evident in some individual responses (asterisk) but not others. When spikelets are not evident, individual synaptic events can be resolved in the compound EPSP (arrowheads).