Figure 1.

Variations of the four-object temporal order memory tasks tested. (a) Effect of different ISIs on temporal order memory performance. Animals were presented with a sequence of four objects with either a 5 min or 60 min ISI between each object. In the test phase, animals were presented with either the first and fourth object from the sequence (long lag) or the second and third object from the sequence (short lag). (b) Effect of varying the delay between S2 and S3 on temporal order memory performance. The delay between S1 and S4 was kept constant, while the delay between S2 and S3 was varied; in the short-delay condition, the delay between S2 and S3 was 10 min, and in the long-delay condition, the delay was 160 min. (c) Testing recognition memory of the objects presented in the sequence, the animals were presented with a sequence of four objects with an ISI of 60 min and the animals were presented with one object from the sequence and a novel object at the test phase.