Memory consolidation, neural substrate of reward, and addiction

OBJECTIVES: The present article aims to analyze the associations among reward and learning and memory processes. DEVELOPMENT: Several studies have described how information on rewards influences behavior and how the brain uses this information to control learning and memory processes. The nature of reward seems to be processed in different ways by neurons in distinct brain structures, ranging from the detection and perception of rewards to the use of information about predicted rewards for the control of goal-directed behavior. The neural substrate underlying this processing of reward information is clearly involved in improving learning and memory processes. Evidence from several experimental studies indicates that this neural system can facilitate memory consolidation in a wide variety of learning tasks. From a molecular perspective, certain cardinal features of reward have been described as forms of memory. Studies of human addicts and of animal models of addiction have shown that chronic drug exposure produces stable cellular and molecular changes in the brain that underlie the long-lasting behavioral plasticity associated with addiction. These molecular and cellular adaptations involved in addiction also seem to be involved in learning and memory processes. Dopamine seems to be a critical common signal to activate various genetic mechanisms that ultimately remodel synapses and circuits. CONCLUSIONS: Although memory is an active and complex process mediated by different brain areas, the neural substrate of reward seems able to improve memory consolidation in several paradigms. Therefore, we believe that there are many equivalent traits between reward and learning and memory processes.