Adolescence and Reward: Making Sense of Neural and Behavioral Changes Amid the Chaos

Abstract

Adolescence is a time of significant neural and behavioral change with remarkable development in social, emotional, and cognitive skills. It is also a time of increased exploration and risk-taking (e.g., drug use). Many of these changes are thought to be the result of increased reward-value coupled with an underdeveloped inhibitory control, and thus a hypersensitivity to reward. Perturbations during adolescence can alter the developmental trajectory of the brain, resulting in long-term alterations in reward-associated behaviors. This review highlights recent developments in our understanding of how neural circuits, pubertal hormones, and environmental factors contribute to adolescent-typical reward-associated behaviors with a particular focus on sex differences, the medial prefrontal cortex, social reward, social isolation, and drug use. We then introduce a new approach that makes use of natural adaptations of seasonally breeding species to investigate the role of pubertal hormones in adolescent development. This research has only begun to parse out contributions of the many neural, endocrine, and environmental changes to the heightened reward sensitivity and increased vulnerability to mental health disorders that characterize this life stage.

A three‐wave longitudinal study of subcortical–cortical resting‐state connectivity in adolescence: Testing age‐ and puberty‐related changes

“…Recent animal evidence suggests that puberty may be a critical driver in reward‐circuitry development. For instance, animal work has observed a reduction in medial PFC volume and synapses in postpubertal rats, and neuronal losses during pubertal onset (Walker et al, ; Willing & Juraska, ). In humans, decreases in gray matter density in frontal regions (Peper et al, ), as well as hippocampus, amygdala, and caudate volumes (Goddings et al, ; Wierenga et al, ) have been related to pubertal development, but—to our knowledge—these findings are one of the first to test and compare effects of pubertal development on RS functional connectivity (but see also Ernst et al, ).…”

Dissociation of Puberty and Adolescent Social Development in a Seasonally Breeding Species

“…The use of seasonal species to study such interactions has several unique advantages over gonadectomy and hormone replacement [20]. SD-rearing circumvents potential confounds that can accompany gonadectomy, including early-life surgical stress [21,22] and compensatory neuroendocrine changes after removal of gonadal steroid negative feedback [23].…”

Signatures of sex: Sex differences in gene expression in the vertebrate brain

“…During adolescence, the brain undergoes significant synaptic pruning which extends into the twenties in humans and P35-45 in rodents (Figure 1). Connectivity within the mesolimbic reward pathway continues to develop and is modulated by hormone signaling (reviewed in Walker et al, 2017;Delevich, Wren Thomas, & Wilbrecht, 2019). This pathway intersects with social behavior circuitry to modulate sex differences in motivated behaviors such as parenting, sexual behavior, threat avoidance, and intake of drugs of abuse (Becker, 2009;Gee et al, 2018;O'Connell & Hofmann, 2011).…”