Mesolimbic regions of the brain, particularly the nucleus accumbens are involved in reward, risk taking, and addictive behaviors. Galvan et al have looked at the development of this system by making behavioral and fMRI brain imaging measurements in adults and children in response to tasks manipulating reward values. Accumbens activity in adolescents looked like that of adults in both extent of activity and sensitivity to reward values, although the magnitude of activity was exaggerated. In contrast, the extent of orbital frontal cortex activity in adolescents looked more like that of children than adults, with less focal patterns of activity. Their findings suggest that the accumbens becomes disproportionately activated relative to later maturing top–down control systems in the orbital frontal cortex, biasing the adolescent's action toward immediate over long-term gains.
Localization of nucleus accumbens (A) and orbital frontal cortex (C) activation to reward.
Credit: Journal of Neuroscience