Bilateral entorhinal cortex lesions impair DRL performance in rats

Abstract

The entorhinal cortex participates in a variety of spatial and locomotor behaviors that are thought to be mediated by the hippocampal formation. The present study examined the possibility that the entorhinal area contributes to the maintenance of an operant behavior in which the hippocampus is also implicated-differential reinforcement of low-rate responding (DRL). Rats with bilateral entorhinal cortex lesions or sham operations were tested for retention of a preoperatively learned DRL (lO-sec delay) task. Rats with entorhinallesions were impaired on measures of response rate, temporal discrimination, and response efficiency for 2 to 3 weeks after surgery. Histological analyses indicated that all the rats sustained complete entorhinallesions. The entorhinal cortex may be an important component of the hippocampal formation contributing to the performance of DRL tasks.