Neural Coding of Reward in Ventral Forebrain

University Of Michigan At Ann Arbor, Ann Arbor MI

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Abstract

DESCRIPTION (provided by applicant): In this study, we will investigate possible neural coding mechanisms for reward liking and wanting, which are important to drug addiction as well as motivation for natural rewards. We will focus on neural firing in the ventral pallidum (VP), which is a primary target of brain mesolimbic circuits involved in wanting and liking rewards. We will test the idea that neural activity in the ventral pallidum encodes stimuli that are hedonic rewards, such as sucrose taste, and encodes also conditioned incentive stimuli that predict rewards, such as Pavlovian-trained sounds. We will record activity of single neurons in rats trained to discriminate a tone (CS+) that predicts a sucrose reward (UCS) from a tone that predicts nothing (CS-). We anticipate finding that VP neurons have population codes and firing rate codes both for hedonic UCS receipt and for predictive CS+s. To find out whether such codes reflect the value of these reward stimuli or else more stable properties (sensory features or prior associations), we will test VP firing after manipulations that change CS or UCS reward values (e.g., neural sensitization, taste aversion conditioning). Based on preliminary work, we anticipate that VP neuronal firing rates will code CS and UCS reward values independently of other features, providing neural bases for integrating reward liking and wanting. Our findings could lead to a better understanding of the pathophysiology of reward and new therapeutic tactics for drug abuse.