Behavioral Apparatus

An 8-arm radial maze was used throughout the entire experiment for all tasks. The radial maze allows testing in both RM and WM in one single spatial environment and thus permits to determine a clear distinction between processes required for these different forms of memory. The apparatus consisted of an elevated radial maze.⁴⁰ Eight arms (65 cm long × 12 cm wide) ended by rectangular platforms (17 cm × 25 cm) were arranged around an octagonal central platform (33 cm diameter). Each arm could be automatically moved in an upward (open) or a downward position (close) by the experimenter monitoring rat movements using a video camera above the maze while located in a room directly adjacent to the testing room. Lowering (closing) an arm prevented access to the platform located at its end. Food rewards (Dustless Precision Pellets; Bioserve, Frenchtown, NJ) could be placed in squared food wells of 2 × 2 cm and 0.5 cm deep located on each rectangular platform. The maze was located in a room with a number of extramaze cues (e.g., door, furniture) allowing the rats to use spatial (hippocampal-dependent) memory to remember locations of food rewards. All rats' movements in the maze were recorded for off-line examination.