Figure 3.
DA modulates integration of EPSPs. A, Overlayed traces of a train of 10 EPSPs demonstrate that DA (gray traces) enhances summation at a depolarized membrane potential but decreases summation near the resting membrane potential. The right panel plots the time course of the effects of DA in two neurons (black circles are summation of 10 EPSPs; gray circles are summation of 5 EPSPs). The time course of the effects of DA in this example indicate that it began shortly after application of DA (at solid bar) and returned close to baseline. B, As demonstrated previously, the effects of DA on summation near Vrest are blocked by ZD7288 but not the effects of DA at a depolarized membrane potential. C, DAergic modulation of the summation of five EPSPs also displayed a voltage dependence and allows more isolated examination of processes involved in DAergic enhancement of integration at depolarized membrane potentials because effects on summation of EPSPs near Vrest are minimal. *p < 0.05, significant difference in a paired t test comparison between baseline and post-DA conditions.