The entorhinal cortex-nucleus accumbens pathway and latent inhibition: a behavioral and neurochemical study in rats

Latent inhibition (LI) refers to the decrease in conditioned response produced by the repeated nonrein-forced preexposure to the to-be-conditioned stimulus. Experiment I investigated the effects of electrolytic lesions of the entorhinal cortex on LI in a conditioned emotional response procedure. Entorhinal cortex lesions attenuated LI. Experiments 2 and 3 investigated whether this attenuation of LI could result from a modification in nucleus accumbens (NAcc) dopamine (DA) release. Rats with entorhinal cortex lesions displayed normal spontaneous and amphetamine-induced locomotor activity, as well as normal basal and amphetamine-induced release of DA within the NAcc (assessed by microdialysis). Taken together, these results show that entorhinal cortex lesions disrupt LI in a way that is unlikely to be due to an alteration of DA release within the NAcc.