Rats were trained in the eight arm radial maze tasks until they visited each arm and committed no more than one re-entry error on three consecutive sessions. Once these criteria were achieved, the subjects underwent stereotaxic surgery, as described above. Two weeks after cannulae implantation, the rats were re-trained to these same criteria (i.e. 0 or 1 re-entry errors on three consecutive days) before drug testing in the radial arm maze. The initial training period required between 15 and 20 sessions and the post-surgical training required an additional 8 to 10 days. In each experiment, rimonabant or vehicle was administered 10 min before CP-55,940, Δ9-THC, or vehicle. Rats were then tested in the radial arm maze 20 min later. These time points were based on previous experiments from our laboratory (Lichtman and Martin 1996). All drug conditions were tested in a counterbalanced order, with 5-7 days between tests. Additionally, the rats received a minimum of two days of radial arm maze training between test days.
