Dopamine and noradrenaline release in the prefrontal cortex of rats duringclassical aversive and appetitive conditioning to a contextual stimulus: interference by novelty effects

Extracellular dopamine and noradrenaline concentrations in the medial prefr ontal cortex were determined using online microdialysis in freely moving ra ts during classical appetitive or aversive conditioning to a contextual con ditioned stimulus (CS). As CS we used placement in a Skinner box where eith er foot shocks or food pellets were delivered as unconditioned stimuli. In the aversive conditioning group we observed a conditioned increase in norad renaline, but not in dopamine release, upon a final exposure to CS-alone. O ther conditioned effects were possibly masked by the continued presence of novelty and handling effects of the transfer to the Skinner box. (C)1999 El sevier Science ireland Ltd. All rights reserved.