Figure 1.

Schematic of procedures for the object and object-in-location recognition memory tasks. Each trial of both tasks included a study phase and a test phase. For the object recognition memory task, rats encountered two novel objects during the study phase, then a duplicate of one of the study objects and a different novel object during the test phase. For the object-in-location memory task, rats encountered three novel objects during the study phase and three duplicates of the study phase objects during the test phase. One duplicate was placed in the same location as it appeared during the study phase, and two duplicates swapped locations. Rats completed two trials of each task each month from 5 to 12 months of age. Unique novel objects were used for each trial, and locations were counterbalanced across trials (see Materials and Methods for details).