Lesions of the lateral entorhinal cortex disrupt non-spatial latent learning but spare spatial latent learning in the rat (Rattus norvegicus)

Abstract

The current study examined the function of the lateral entorhinal cortex (LEC) in a non-spatial latent learning task and a spatial latent learning task. Latent learning is the acquisition of neutral information that does not immediately influence behavior, but can be recalled and utilized when it becomes relevant to the animal. Based on previous research, it was predicted that the LEC would be necessary for latent learning of non-spatial information, but would not be necessary for latent learning of spatial information. Forty-two male Sprague Dawley rats (Rattus norvegicus) were either given pretraining neurotoxic lesions restricted to the LEC or were given sham (SH) lesions. The rats were then trained and tested on two latent learning tasks: the Latent Cue Preference (LCP) task which assesses single-cue (non-spatial) latent learning and a spatial latent learning task utilizing a Barnes maze. Results showed that rats with LEC lesions were impaired on the nonspatial LCP task compared to SH rats, but showed no impairment on the spatial latent learning task. Therefore, the LEC appears to be selectively involved in processing non-spatial latent learning and does not process, or is at least not necessary for, spatial latent learning. These findings indicate a specific role of the LEC in information processing and provide new information about the function of the entorhinal cortex.