Figure 3.

Cumulative record showing within-session pattern of responding for monkey G during a representative vehicle (V) session and sessions preceded by the administration of 0.25, 0.5, and 1.25 μmol/kg of IMD or 1 μmol/kg ALP alone, and a combination of this dose of ALP with 1.25 μmol/kg IMD on days 4, 8, and 15 of repeated IMD (1.25 μmol/kg) treatment. The same single dose of ALP was administered alone on day 2 after discontinuation of a 17-day repeated IMD treatment. The response pen stepped with each correct response and was deflected downward each time food was presented. Errors are indicated by the event pen (below each record), which was held down during each timeout. The event pen was deflected and the response pen reset each time the component of the multiple schedule changed. Each session began with an acquisition component (A) and then alternated with a performance component (P) after 10 reinforcements or 15 min, whichever occurred first.