Dose-dependent effects of prefrontal dopamine on behavioral state in rats.

An inverted-U mechanism has been proposed to explain findings that both under- and overstimulation of dopamine (DA) receptors in medial prefrontal cortex (mPFC) result in working memory impairments. Dopamine release in the mPFC is also associated with the mediation of other behavioral processes such as affective regulation, reward, and nociception. The present studies investigated mPFC DA dose-dependent effects on the performance of tasks that tap these other processes, including delayed alternation in the T maze for working memory, a water maze task for escape, the elevated plus maze for anxiolytic/anxiogenic effects, place preference conditioning for reward effects, the tail flick test for nociception, and a measure of locomotor activity for general arousal.