Abstract
The role in spatial divided and sustained attention of D1 and D2-like dopamine (DA) receptors in the rat prelimbic medial prefrontal cortex (mPFC) was investigated in a five-choice serial reaction time task. Rats were trained to detect brief flashes of light (0.5-0.25 sec) presented randomly in a spatial array of five apertures. When performance stabilized, animals received bilateral microinfusions of either the D1 DA receptor antagonist SCH 23390, the D1 DA receptor agonist SKF 38393, or the D2 DA antagonist sulpiride into the mPFC. Rats were divided into two groups, with low (<75% correct) and high (>75%) baseline levels of accuracy. Infusions of the D2 receptor antagonist sulpiride had no significant effect on any task variable. SCH 23390 (0.3 microg) selectively impaired the accuracy of attentional performance in rats in the high baseline condition. By contrast, SKF 38393 (0.06 microg) enhanced the accuracy of attentional performance in the low baseline condition, a lower dose (0.03 microg) also increasing the speed of making correct responses. Finally, the beneficial effects of SKF-383893 on choice accuracy were antagonized by SCH 23390 (1.0 microg). The results provide apparently the first demonstration of enhanced cognitive function after local administration of a D1 receptor agonist to the mPFC and suggest dissociable roles of D1 and D2 DA receptors of the mPFC in modulating attentional function.