Earlier development of the accumbens relative to orbitofrontal cortex might underlie risk-taking behavior in adolescents.
ABSTRACT Adolescence has been characterized by risk-taking behaviors that can lead to fatal outcomes. This study examined the neurobiological development of neural systems implicated in reward-seeking behaviors. Thirty-seven participants (7-29 years of age) were scanned using event-related functional magnetic resonance imaging and a paradigm that parametrically manipulated reward values. The results show exaggerated accumbens activity, relative to prefrontal activity in adolescents, compared with children and adults, which appeared to be driven by different time courses of development for these regions. 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. These findings suggest that maturing subcortical systems become disproportionately activated relative to later maturing top-down control systems, biasing the adolescent's action toward immediate over long-term gains.
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ABSTRACT: Throughout our lives, we face the important task of distinguishing rewarding actions from those that are best avoided. Importantly, there are multiple means by which we acquire this information. Through trial and error, we use experiential feedback to evaluate our actions. We also learn which actions are advantageous through explicit instruction from others. Here, we examined whether the influence of these two forms of learning on choice changes across development by placing instruction and experience in competition in a probabilistic-learning task. Whereas inaccurate instruction markedly biased adults' estimations of a stimulus's value, children and adolescents were better able to objectively estimate stimulus values through experience. Instructional control of learning is thought to recruit prefrontal-striatal brain circuitry, which continues to mature into adulthood. Our behavioral data suggest that this protracted neurocognitive maturation may cause the motivated actions of children and adolescents to be less influenced by explicit instruction than are those of adults. This absence of a confirmation bias in children and adolescents represents a paradoxical developmental advantage of youth over adults in the unbiased evaluation of actions through positive and negative experience.Cognitive Affective & Behavioral Neuroscience 01/2015; DOI:10.3758/s13415-014-0332-5 · 3.87 Impact Factor
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ABSTRACT: Changes in reward processing have been identified as one important pathogenetic mechanism in alcohol addiction. The nonsynonymous single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene (rs6265/Val66Met) modulates the central nervous system activity of neurotransmitters involved in reward processing such as serotonin, dopamine, and glutamate. It was identified as crucial for alcohol consumption in healthy adults and, in rats, specifically related to the function in the striatum, a region that is commonly involved in reward processing. However, studies in humans on the association of BDNF Val66Met and reward-related brain functions and its role for alcohol consumption, a significant predictor of later alcohol addiction, are missing. Based on an intermediate phenotype approach, we assessed the early orientation toward alcohol and alcohol consumption in 530 healthy adolescents that underwent a monetary incentive delay task during functional magnetic resonance imaging. We found a significantly lower response in the putamen to reward anticipation in adolescent Met carriers with high versus low levels of alcohol consumption. During reward feedback, Met carriers with low putamen reactivity were significantly more likely to orient toward alcohol and to drink alcohol 2 years later. This study indicates a possible effect of BDNF Val66Met on alcohol addiction-related phenotypes in adolescence.
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ABSTRACT: There is a paucity of experimental data addressing how peers influence adolescent risk-taking. Here, we examined peer effects on risky decision-making in adults and adolescents using a virtual social context that enabled experimental control over the peer "interactions." 40 adolescents (age 11-18) and 28 adults (age 20-38) completed a risk-taking (Wheel of Fortune) task under four conditions: in private; while being observed by (fictitious) peers; and after receiving 'risky' or 'safe' advice from the peers. For high-risk gambles (but not medium-risk or even gambles), adolescents made more risky decisions under peer observation than adults. Adolescents, but not adults, tended to resist 'safe' advice for high-risk gambles. Although both groups tended to follow 'risky' advice for high-risk gambles, adults did so more than adolescents. These findings highlight the importance of distinguishing between the effects of peer observation and peer advice on risky decision-making.Frontiers in Psychology 12/2014; 5:1476. DOI:10.3389/fpsyg.2014.01476 · 2.80 Impact Factor