From Hedonia to Neural Circuits: A Historical and Neurobiological Framework of Reward Processing

Reward is a central concept in neuroscience, yet its contemporary meaning is the result of a long conceptual and experimental transformation. This review traces the historical development of reward processing from philosophical accounts of pleasure to current neurobiological frameworks. We first examine how classical and early modern philosophical traditions explored pleasure as both an ethical concern and a factor influencing human motivation and behavior, emphasizing the roles of desire, experience, and anticipated consequences. We then follow its transition into experimental psychology, where Thorndike, Pavlov, and Skinner established objective approaches to the study of learning, prediction, and reinforcement. The discovery of intracranial self-stimulation by Olds and Milner subsequently made it possible to investigate reinforcement through direct manipulation of the brain, opening the way to neurochemical accounts centered on catecholamines and, eventually, dopamine. Electrophysiological and behavioral studies further refined this framework by identifying patterns of dopaminergic activity consistent with reward prediction-error signaling and by distinguishing partially dissociable components of reward, including hedonic impact (“liking”), incentive motivation (“wanting”), and learning. These advances shifted the search for a unitary reward substrate toward the study of distributed and interacting neural systems in which valuation, internal state, memory, emotional significance, prediction, and action selection are integrated across time. From this historical perspective, reward emerges not as a fixed neural circuit or a synonym for pleasure, but as a dynamic neural function through which experience and present conditions are integrated to anticipate outcomes, guide adaptive action, evaluate its consequences, and update future behavior.