A novel neurobehavioral framework of the effects of positive early postnatal experience on incentive and consummatory reward sensitivity.

Early postnatal experience has a profound influence on the development of organisms. In this integration, we provide a novel framework of the neurobehavioral pathways through which positive early postnatal experience acts to enhance adult reward sensitivity. The heterogeneity of the construct of reward and the underlying neurotransmitter systems (i.e., dopamine in incentive reward, opioids in consummatory reward, and oxytocin in orienting the reward systems to social cues) are first described as a means of organizing the discussion. Then, for each neurotransmitter system, their early postnatal ontogenesis is depicted for identifying potential sensitive periods for the effects of early experience. This is followed by the presentation of a model of the neurobehavioral foundation of two main forms of positive early postnatal experience that, with their essential components - novelty and positive tactile stimulation, facilitate the development of incentive and consummatory reward systems. Next, a detailed analysis of the major effects of positive early prewean and postwean experience on the neural and behavioral functioning of each neurotransmitter system is reviewed. The data support the neurobehavioral model presented, which theorizes that essential components of positive early experience enhance incentive and consummatory reward sensitivities through early activation of particular neural pathways. These activity-dependent effects are sustained via structural modifications of underlying neural circuitries.