Behavioural procedure
The experiment used the same apparatus as Experiment 1 and 2. Animals were initially habituated to a T-maze or a Y-maze for 3×12 min/day for three days. After each 12 min habituation trial, the animal was removed from the maze and placed in the holding cage while the maze was wiped with a disinfectant. Animals received sham saline injections (4 ml/kg) on the last two days for habituation to the injection procedure. Testing took place on the fourth day over 2×15 min. In the first 15 min phase of the test, the maze was maintained in the same configuration as during habituation. In the second 15 min phase of the test, one of the previously open arms was closed while an arm 45° to the north or south was opened. The maze configuration (T-maze vs. Y-maze) and location of the novel arm (N vs. S) were counterbalanced across the experimental groups.