Figure 1.

Experimental apparatus and design of the sequential food-water navigation task with variable delayed rewards. A, Open field, reward cylinders (food site, water site) and tone cylinder (tone site) for the task. Windows for nose pokes (reward locations) are indicated. The tone cylinder also contained a small window at the same position as the reward cylinders. B, Schematic of the movements required for the rats to receive rewards at both sites. The rats performed the task under two reward conditions. In the SDR condition, the rats obtained a reward after 2 s of nose poking at each reward site. In the LDR condition, the rats were required to poke their nose for 7–11 s before obtaining the reward. Each reward condition lasted for 30 min and was preceded by a rest period. C, Locations of the microdialysis probes in the DRN. Black bars represent the 2 mm length of the dialysis membranes. Numbers beside each plate correspond to millimeters from bregma. Coronal drawing modified from Paxinos and Watson (1998) with permission.