IPSC decay time constant is determined by the type of the postsynaptic target cell. A, B, Sequential triple recording from a presynaptic BC and a postsynaptic BC (left traces, first pair) and the same presynaptic BC and a postsynaptic GC (right traces, second pair obtained subsequently after pipette removal from the postsynaptic BC). Presynaptic action potential (top), single unitary IPSCs (6 sweeps superimposed, center), and average IPSC (from 22 sweeps, bottom) are depicted. Shown are single action potential in A and pair of two action potentials inB (10 msec interpulse interval). Note the difference in decay time constants but the comparable paired-pulse ratio. The fast inward current preceding the IPSC in the BC–BC traces represents putative electrical coupling. C, Summary bar graphs of 20–80% rise time, latency, and amplitude-weighted average decay time constant. D, Summary bar graphs of peak IPSC amplitude (left) and paired-pulse ratio (A₂/A₁ , 10 msec interval, right). Bars indicate means (with SEMs). Data from seven sequential triple recordings;circles connected by lines represent data from the same triple recording. Note a significant difference in the decay time constant (**p ≤ 0.006), determined by the type of the postsynaptic target cell.