Disturbance of rat lever-press learning by hippocampo-prefrontal disconnection

To determine whether the medial prefrontal cortex (PFC), ventral hippocampus and hippocampo-PFC pathway are involved in operant lever-press learning, we conducted lidocaine injections to these brain sites. Rats were injected immediately after lever-press acquisition in the first training, and the second 5-min test the next day. Results showed the response rate of either PFC- or ventral hippocampus-inactivated rats to be lower than that of control rats in the test the next day. Rats having lidocaine injected into the unilateral ventral hippocampus combined with contralateral medial PFC also showed lower response rate in their tests. These results suggest that hippocampo-PFC disconnection disturbs operant learning.