Mixed attentional and executive deficits in medial frontal cortex lesionedrats

Two groups of rats were trained to detect brief, unpredictable visual stimu li in attentional paradigms with different response selection requirements. Animals had to hold their heads in a central location for a variable delay and then respond to either the same (same condition) side as or the opposi te (opposite condition) side to where the visual stimulus had occurred. Fol lowing bilateral excitotoxic lesions of the medial prefrontal cortex (mPFC) , rats in the same condition were impaired relative to controls, as reveale d by reductions in choice accuracy and speed of responding. In the opposite condition, mPFC-lesioned animals performed at chance and were faster than controls to respond to the target. These results extend previous findings o f accuracy deficit in mPFC-lesioned rats in a five-choice serial reaction t ime task in which the animals are not required to respond to targets from a fixed position. In addition, the finding of a larger deficit in the opposi te condition suggests a more prominent role for the mPFC in the selection o f difficult, "incompatible" responses relative to easy, "compatible" ones.