Development of compulsive drug seeking is hypothesized to involve neural adaptations in brain circuits mediating motivation and reward. Although these circuits have been elucidated by previous work, alterations in functional connectivity in these circuits by abused drugs remain to be described. Therefore, in these experiments, we used manganese-enhanced magnetic resonance imaging (MEMRI) for measuring functional activity changes induced by voluntary alcohol drinking in alcohol-preferring AA (Alko Alcohol) rats. The usefulness of MEMRI for functional imaging is based on the ability of Mn²⁺ ions to enter excitable cells via voltage-gated Ca²⁺ channels and accumulate into neurons in proportion to neural activity. The accumulation of Mn²⁺ in active brain regions can be seen as enhanced signal intensity in T1-weighted scans. When administered during voluntary alcohol drinking, the 120 mg/kg MnCl₂ dose during seven days initially decreased alcohol intake, but during the latter half of MnCl₂ administration alcohol drinking recovered. MEMRI at the end of the 7-day MnCl₂ infusion revealed widespread enhancement of T1 signal in alcohol-drinking rats compared to water-drinking controls. The brain regions showing activation included the terminal fields of the mesolimbic pathway, including the nucleus accumbens, striatum, and areas of prefrontal cortex. These findings demonstrate the feasibility of mapping brain activation in freely behaving rats with MEMRI. The activity patterns suggest that voluntary alcohol drinking by rats increases the functional activity of various interconnected brain regions, including circuits previously suggested for mediation of alcohol reinforcement.