Figure 1.

Schematic of the object-place paired association (OPPA) task and discrimination control conditions. A two-arm radial maze was used for all testing conditions. (A) During testing on the OPPA task, rats were required to discriminate between two distinct objects (e.g., girl figurine or owl); however, in the left arm the girl figurine was rewarded (green check mark) and not the owl (red X). In the right arm, the rats had to discriminate between the same two objects but the owl was the correct choice and the girl figurine was not rewarded, requiring rats to use an object-in-place rule. The placement of rewarded objects over the left or right food wells varied pseudorandomly across trials. (B) For the object discrimination control task, one arm of the maze was blocked and the rat shuttled between the central circle and choice platforms between discrimination trials. The same object was always rewarded (bear; green check mark). (C) The left-versus-right side discrimination control was carried out in the opposite arm of the maze than that used for object discrimination testing. For each trial, two identical objects covered both food wells and a single well on one side was always rewarded across trials (e.g., left well, green check mark). Whether the left or right well was the correct choice varied between rats. See the online article for the color version of this figure.