Figure 8. Odor recognition test.

(A) In a first acquisition test of 2 min duration, both holes were odorized with the same compound and were equally explored by the animals. In a recall test after a delay of 30 min, one hole was odorized with the previously presented odor during the acquisition test, while the other hole contained a new and unknown odorant compound. The placement of the familiar and new odors was randomized to avoid place preference bias. (B) Odor recognition test. Rats were subjected to the acquisition test (2 min) with either carvone or limonene present in both holes of the hole-board. The percent investigation times (vertical axis) of both holes were similar (open bars: “Acquisition,” Hole 1 and Hole 2). Immediately following the acquisition test, all animals received an i.p. injection of control (physiological saline) and were submitted to the recall test after a delay of 30 min. The bars (Recall-novel odor) represent the mean exploration time of the hole containing the new odor, expressed as the percentage of the total exploration time of both holes. At a delay of 30 minboth holes were equally explored, indicating that rats could no longer remember the familiar odor (one-sample t-test; p > 0.05).