Figure 7

Dopamine modulation of multicomponent responses. A. In each of six experiments with multiple components, DA inhibited the components differentially. In experiment number 6, there were three components and each was differentially modulated. Component 1 (Comp1) was measured directly; components 2' and 3' were measured from the calculated responses after exponential extrapolation of the preceding component (or in experiment 6, the preceding two components). B. Differential DA modulation is illustrated in traces from experiment 5, in which we were successful in testing the effects of both D1 and D2 agonists. (B1) The control response had two components (1 and 2). Comp1 was extended by exponential curve fitting and then subtracted from the control trace to isolate Comp2' (blue traces). The sections of the traces measured (for Comp1 and Comp2') are shown thickened. DA (gray thick trace) inhibited Comp1 to 33% of control, while it had no effect on 2' (light blue thick trace). Bicuculline (Bic) blocked both components, nearly completely. (B2) SKF38393 (SKF) facilitated Comp1 (gray thick trace), but had no effect on Comp2' (light blue thick trace). (B3) Quinpirole (Quin), inhibited Comp1 (gray thick trace) and facilitated Comp2' (light blue thick trace). The dashed line indicates the zero current baseline.