Figure 2.

Massed training at different water temperatures differentially affects the performance of rats in the spatial task. (A) All animals trained at 19°C (Cold Water) have acquired the task. Animals trained at 25°C were divided into two groups, animals that reached the platform four consecutive times in 20 sec or less [Warm Water (+)] and animals that showed higher latencies in reaching the platform [Warm Water (-)]. A significant difference in performance (measured as escape latency) was found between the Warm Water (-) group and both the Cold Water (P < 0.001) and the Warm Water (+) (P < 0.001) groups, with no significant difference between the Cold Water and the Warm Water (+) groups. (B) A quadrant analysis test was conducted 1 h following the last behavioral trial. Rats in the Cold Water group showed a significant bias to swim the longest distance within the quadrant in which the platform had been located previously (Q2; ^* significant difference from chance level (25%): P < 0.0001). In contrast, the Warm Water (+) and the Warm Water (-) groups showed no such bias. This may suggest a primary difference in the quality of the spatial memory between the animals trained in cold water and the good performers of the warm water group, which although they performed well in training (A), failed to perform well in the test (B).