Previous studies have shown that dentate gyrus damage render rats less efficient than sham-operated controls in the performance of a differential reinforcement of low rates of responding (DRL-20 s) task acquired prior to the lesion; even though the lesioned rats were able to postpone their responses after a previous bar press, they seem to underestimate time relative to sham-operated controls, which interferes with their performance. This study investigated the effects of multiplesite, intradentate, colchicine injections on the acquisition and performance of a DRL-20 s task in rats not exposed to preoperatory training, i.e., trained after the lesion. Results showed that the lesioned rats improved along repetitive training in the DRL-20 s task; however, relative to the sham-operated controls, their acquisition rate was slower and the level of proficiency achieved was poorer, indicating that damage to the dentate gyrus interferes with temporal discrimination.
Temporal discrimination; DRL task acquisition; hippocampus; dentate gyrus
