The role of the medial prefrontal cortex and nucleus accumbens in the motivation and reinforcement processes underlying food-seeking behavior

This dissertation reviews behavioral concepts of reinforcement and motivation, and suggests the behavioral effects of food deprivation as a point of convergence between these two disparate constructs. In spite of this, neurobiological theories of motivation and reinforcement largely ignore food deprivation as a variable. Presented here are the results of studies testing the relationship between food deprivation and goal-directed behavior, as well as the neural substrates of such behaviors. Four studies were designed and executed, with the following broad aims: (1) to determine the nature of food deprivation's influence on the output of two different types of behavior, a food-reinforced operant behavior and spontaneous locomotion; (2) to determine whether mesocorticolimbic terminal regions process information about behaviorally-relevant periods of food deprivation and food presentation; and (3) to assess effects of both targeted inactivation and dopamine receptor blockade of mesocorticolimbic terminal regions on food-reinforced behavior during varying conditions of food deprivation. These results are reviewed in terms of contemporary theory about the neurophysiology and behavioral function of the mesocorticolimbic dopamine system and the brain substrates of decision-making.