Fig. 5. Ca²⁺-induced potentiation of excitatory and inhibitory synaptic transmission improves spike capacity and timing precision. Effect of intracellular Ca²⁺-induced synaptic potentiation on spike encoding and neuronal intrinsic properties. The potentiation of excitatory and inhibitory synaptic inputs was mimicked by strong depolarization and hyperpolarization pulses. Data were obtained under control conditions (), adenophostin-A infusion alone (gray triangles) or adenophostin-A together with strong depolarization (new threshold stimuli, Tsti') and AHP (). (A) Strong depolarization pulses reduce adenophostin-A-induced prolongation of the absolute RP. There is no statistical difference between adenophostin-A-treated () and control () RPs in spike 1; however, a difference was observed with spike 3 for adenophostin-A infusion alone versus control ( versus , respectively). (B) The mixture of strong depolarization/AHP pulses lowers adenophostin-raised V_ts–V_r () compared with that recorded with adenophostin-A alone (gray triangles, P<0.05). (C) Spike waveforms superimposed from 20 traces with adenophostin-A treatment alone. (D) Waveforms from 20 traces under adenophostin-A infusion with strong depolarization and AHP. (E) ISI values for corresponding spikes 2-4 between the three conditions are statistically different (P<0.01). (F) SDST values for spikes 2-5 under strong depolarization and AHP are significantly different (P<0.01) to those in adenophostin-A-treated and control.