Delay-dependent modulation of memory retrieval by infusion of a dopamine D1 agonist into the rat medial prefrontal cortex

Dopamine (DA) in the medial prefrontal cortex (PFC) can modulate the short-term retention of information and other executive functions. The present study examined whether administration of a DA D-1 agonist into the PFC could have differential effects on memory retrieval in circumstances in which memory was either excellent or poor. Separate groups of rats were trained on a delayed version of the radial maze task. On the test day, the delay between the phases was either 30 min or 12 hr. Infusions of the D-1 receptor agonist SKF 81297 (0.05, 0.10, or 0.20 mug/0.5 mul) into the PFC before the test phase improved memory retrieval after a 12-hr delay but disrupted performance after a 30-min delay. These data suggest that D-1 receptor activity can exert differential effects over PFC function, depending on the strength of the memory trace. When memory is decremented by an extended delay, activation of PFC DA D-1 receptors by an agonist can improve cognitive function.