Figure 6.

Recording and analysis of meIPSCs. A, To determine an appropriate stimulus intensity to elicit meIPSCs, a set of evoked IPSCs is activated by titrating stimulus intensities (administered through a patch electrode) to find small all-or-none events. This titration is illustrated as an increase in the charge transfer of each event (·) from failures at 10 and 12 μA, to no failures and predominantly large events (>100 pA; inset) at stimulus intensities >16 μA. Within a narrow range of stimulus intensities, in this case 14 μA, a mixture of failures and small (30 pA; inset) all-or-none events characteristic of meIPSCs are generated. B₁, B₂ To determine that the meIPSC response is from a synapse activated during the moderate stimulus protocol (driven by an alternate large bipolar stimulating electrode), the meIPSC was preceded 100 ms by the eIPSC (Pair-stim) as described in Materials and Methods, and a change in success rate (compared with meIPSC stimuli alone; Cont) was assessed to determine whether the two stimuli interacted. Ten control responses and paired stimuli are overlayed and expanded in B₁ and clearly show a decrease in successful responses in the pairing protocol. B₂, This was true for each cell used in the experiments in Figure 7 (thick line is averaged effect for 8 cells; dotted line shows cell in B₁). ***p < 0.0003.