Fig. 12.

Train-dependent facilitation requires VD modulation. The facilitation of currents evoked by a train of 15 APWs (73 Hz; interspike potential, −120 or −140 mV) plotted as a function of the magnitude of VD inhibition produced by 100 μm NE (•) or GABA (▪). The percentage of facilitation was calculated by % facilitation = 100 − [(p₁₅/p₁) · 100], where p₁₅ andp₁ are the peak amplitudes of currents evoked by the 1st and 15th APWs, respectively. The percentage of VD inhibition was calculated as % VD inh = [(1 −I₃/I₁) − (1 −I₄/I₂)] · 100, where I₁,I₂,I₃, and I₄are peak currents evoked by single APWs in control, control + prepulse, GABA, and GABA + prepulse, respectively. The linerepresents linear regression fit; correlation coefficient, 0.95.