Early life stress and brain function: Activity and connectivity associated with processing emotion and reward

Abstract

Investigating the developmental sequelae of early life stress has provided researchers the opportunity to examine adaptive responses to extreme environments. A large body of work has established mechanisms by which the stressful experiences of childhood poverty, maltreatment, and institutional care can impact the brain and the distributed stress systems of the body. These mechanisms are reviewed briefly to lay the foundation upon which the current neuroimaging literature has been built. More recently, developmental cognitive neuroscientists have identified a number of the effects of early adversity, including differential behavior and brain function. Among the most consistent of these findings are differences in the processing of emotion and reward-related information. The neural correlates of emotion processing, particularly frontolimbic functional connectivity, have been well studied in early life stress samples with results indicating accelerated maturation following early adversity. Reward processing has received less attention, but here the evidence suggests a deficit in reward sensitivity. It is as yet unknown whether the accelerated maturation of emotion-regulation circuits comes at the cost of delayed development in other systems, most notably the reward system. This review addresses the early life stress neuroimaging literature that has investigated emotion and reward processing, identifying important next steps in the study of brain function following adversity.

Keywords: Brain function; Early life stress; Emotion processing; Functional connectivity; HPA axis; Reward processing.

Figure 1.

Conceptual illustration of the possibility of a developmental trade-off associated with accelerated maturation of the emotion processing system following ELS (A) as compared to no developmental trade-off (B). To date, the majority of studies examining functional connectivity following ELS have focused on the development of emotion processing systems, with limited work devoted to the functional development of other systems. Behavioral work in individuals who have experienced childhood poverty, maltreatment, and institutional care suggests that the effects of early adversity extend beyond emotion processing and include difficulty processing reward-related information. As such, it may be that the accelerated maturation of emotion-related systems comes at the cost of the development of other neural systems. Due to differences in the maturational courses of neural systems it will be important for future work to evaluate the relative maturity of emotion and reward processing systems to evaluate the possibility of a developmental trade-off.