Differential involvement of prefrontal cortex, striatum, and hippocampus in DRL performance in mice

Behavioral effects of neurotoxic lesions of the hippocampus, medial prefrontal (prelimbic, infralimbic and anterior cingulate) cortex or dorsal striatum were assessed using a DRL-10s schedule in mice. Post-operative acquisition data indicate that mice with hippocampal, but not prefrontal or striatal lesions received fewer reinforcements during daily 30-min sessions, and were less efficient in the timing of their responses. Additional analysis of inter-response-time (IRT) distributions revealed that the responses of hippocampal-lesioned mice exhibited undistinguishable responses for short IRTs (up to 9s). In addition, prefrontal-lesioned mice demonstrated a degradation of performance with further testing, and a flattened IRT distribution at late test phase, while striatal-lesioned mice behaved similarly to sham-lesioned mice. These results are interpreted in terms of known functions of the hippocampus in behavioral inhibition, and of the prefrontal cortex in executive control/decision making (and time production).