Neuromodulation of excessive reward-directed behavior

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DESCRIPTION (provided by applicant): This project will explore the molecular pathways involved in reward perception and reward-seeking behavior in the honey bee. Most drugs of abuse usurp neural circuitry involved in pleasure and reward seeking; discerning how reward is processed in the brain is essential for understanding how drugs of abuse generate addictive behavior. Forager bees express an excessive reward-seeking drive that is regulated by social feedback, and we will develop this as a natural model for studying reward motivation in a social context. Foragers perform symbolic dances that communicate their estimation of the profitability of their foraging trip to hive-mates. The dance language is a 'declarative' report of reward quality providing a unique system to study reward perception in a simple animal model. We will 1. examine how the biogenic amines modulate reward-directed behavior in the bee. Preliminary results indicate aminergic involvement. We will combine pharmacological treatments with assays of dance and foraging behavior to examine how dopamine, serotonin and octopaine contribute to reward perception and reward-seeking drive in the bee. 2. examine how cocaine distorts reward processing and social behavior in bees. We will study how low doses of cocaine misdirect foraging effort, sensitivity to social feedback on foraging effort and perception of reward reported through dances. The principal significance of this research is that it will establish a new model system for studying the molecular pathways of excessive reward-directed behavior in a simple nervous system. This will set the stage for the use of new and emerging genomic technologies for the bee to explore pathways identified in reward processing in detail, to further develop the bee model system. Extensive conservation of nervous system function at the molecular level across the animal kingdom indicates that the principles of reward coding we aim to elucidate in the bee will have general relevance.