Excitotoxic lesions to the prefrontal cortex of Sprague-Dawley rats do not impair response matching

Perseveration refers to maladaptive persistence of behavior outside appropriate contexts and despite negative outcomes. In humans, perseveration is a symptom of a variety of psychiatric disorders. In rats, perseveration has been observed in reversal learning tasks following lesions of the prefrontal cortex (PFC). However, the exact nature of the impairment underlying this effect remains unclear. Male Sprague-Dawley rats were trained on a novel reversal task that requires switching between two rewarded options varying in effort (concurrent fixed and progressive ratios) necessary to obtain the reward. Following initial training, bilateral lesions of the dorsal PFC, medial PFC, or orbitofrontal cortex were produced by NMDA infusions. When animals were re-tested post-surgery, no significant impairments were found. These results indicate that, in trained rats, the PFC is not necessary for selecting responses on the basis of favorable effort-to-reward contingencies.