Figure 4.

(a) Acquisition of lever pressing response during the 10 sessions of instrumental learning for control (diamonds, n=5), QUIN 0.1 (circles, n=7), and QUIN 0.5 group (squares, n=6). (b) Evolution of instrumental responses during the eight sessions of contingency degradation when the contingency was maintained (white symbols) or degraded (black symbols). (c) Lever pressing rate during the 5-min choice extinction test between levers associated with the previously intact (white) or degraded (black) contingency. Data are expressed as mean±SEM relative to the lever press rate observed during the last session of instrumental training. *P<0.05, NS, nonsignificant (two-way ANOVA).