Differential Roles of Dopamine D1 and D2 Receptors in the Nucleus Accumbens in Attentional Performance on the Five-choice Serial Reaction Time Task

Nucleus accumbens (NAC) dopamine may play a role in attentional and executive processes, as it modulates cortico-limbic inputs, including afferents from the prefrontal cortex. The present study examined the role of NAC dopamine D1 and D2 receptors in visual attentional processes and response control in rats as assessed in the five-choice serial reaction time task (5CSRT). Rats were trained to detect the location of brief (0.5 s) visual targets presented randomly in an array of five apertures to receive food reward. They were tested after bilateral infusions of a D1 receptor antagonist (SCH 23390) and agonist (SKF 38393) and a D2 receptor antagonist (sulpiride) and agonist (quinpirole) into the NAC. While intra-NAC SCH 23390 decreased accurate responding and increased response omissions, SKF 38393 improved accuracy and decreased omissions at the lowest dose (0.1 microg/side). At higher doses, SKF 38393 increased premature 'impulsive' responding. Sulpiride impaired the attentional accuracy of responding and slowed the latency to collect the earned food reward. By contrast, intra-NAC infusions of quinpirole did not significantly affect attentional accuracy, but increased perseverative responding. Optimal performance on the 5CSRT depends on both D1 and D2 receptors in the NAC, but they modulate different aspects of performance. D1 receptor agents had more selective effects on attentional accuracy while D2 receptor stimulation did not affect accuracy or premature responses, but enhanced perseverative responding. The data are discussed in terms of the different functions of NAC dopamine receptors in the processing of information from its different cortico-limbic inputs.