LEARNING AND MEMORYFos expression in mesocorticolimbic areas during heroin place conditioningHonsberger, Michael J.M.; Leri, FrancescoAuthor Information Department of Psychology, University of Guelph, Guelph, Ontario, Canada Correspondence to Professor Francesco Leri, PhD, Department of Psychology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 Tel: +1 519 824 4120; fax: +1 519 837 8629; e-mail: [email protected] Received 24 September 2007; accepted 8 October 2007 NeuroReport: January 8, 2008 - Volume 19 - Issue 1 - p 63-67 doi: 10.1097/WNR.0b013e3282f31d82 Buy Metrics Abstract We studied Fos immunoreactivity within targets of the mesocorticolimbic dopamine systems at different stages of acquisition of heroin place conditioning. Fos was quantified in groups of rats after one or four exposures to 0.3-mg/kg heroin only, or to the conditioning compartment only, or to both heroin and the conditioning compartment, or to neither stimuli. Increases in Fos were found primarily after the first exposure. Further, the medial prefrontal cortex was the only region displaying higher Fos expression in the group exposed to both heroin and conditioning compartment. It is concluded that the medial prefrontal cortex may be the neural site whereby neural representations of novel stimuli with motivational value are associated during associative learning. © 2008 Lippincott Williams & Wilkins, Inc.