In this functional magnetic resonance imaging study, we examined developmental changes in the brain regions involved in reactions to unfair allocations. Previous studies on adults suggested that... Show moreIn this functional magnetic resonance imaging study, we examined developmental changes in the brain regions involved in reactions to unfair allocations. Previous studies on adults suggested that reactions to unfairness are not only affected by the distribution itself but also by the ascribed intentionality of the proposer. In the current study, we employed the mini Ultimatum Game (Falk, Fehr, & Fischbacher, 2003) to examine responder behavior to unfair offers of varying degrees of intentionality. Sixty-eight participants from four age groups (10-, 13-, 15-, and 20-year-olds) carried out the task while fMRI data were acquired. Participants of all ages showed activation in the bilateral insula and dorsal anterior cingulate cortex (dACC) during rejection of unintentional but acceptance of intentional unfair offers. Rejection of unintentional unfair offers further involved increasing activation with age in the temporoparietal junction and the dorsolateral prefrontal cortex. These findings provide evidence for an early developing insula-dACC network involved in detecting personal norm-violations and gradually increasing involvement of temporal and prefrontal brain regions related to intentionality considerations in social reasoning. The results are discussed in light of recent findings on the development of the adolescent social brain network. (C) 2011 Elsevier Inc. All rights reserved. Show less
Several studies have examined the neural effects of working memory practice, but due to different task demands, diverse patterns of neural changes have been reported. In the present study, we... Show moreSeveral studies have examined the neural effects of working memory practice, but due to different task demands, diverse patterns of neural changes have been reported. In the present study, we examined neural effects of practice using a task with different working memory demands within a single practice paradigm. Fifteen adults practiced during 6 weeks with a task that required maintenance and manipulation of information under low and high working memory loads. Functional magnetic resonance imaging (FMRI) data were acquired in the first week and last week of the practice period. Results were compared with results of a control group who did not practice the task. We demonstrated that practice was beneficial for both working memory maintenance and manipulation processes but that these processes were supported by different neural changes. While maintenance trials showed increased activation (i.e., less deactivation) in default-mode regions after practice, manipulation trials experienced increased activation in the striatum. Changes were also observed in left ventrolateral prefrontal cortex (VLPFC), bilateral dorsolateral prefrontal cortex (DLPFC) and left superior parietal cortex (SPC). However, for bilateral DLPFC and left SPC, these changes were not specific to the practice group. These findings illustrate the importance of controlling for test-retest effects in training or intervention studies. Behavioral follow-up tests demonstrated that practice effects lasted over a 6-month period, but the absence of transfer effects indicated that the acquired skills were specific for the practiced working memory task. (C) 2010 Elsevier Inc. All rights reserved. Show less
Recent models hypothesize that adolescents' risky behavior is the consequence of increased sensitivity to rewards in the ventral medial (VM) prefrontal cortex (PFC) and the ventral striatum (VS),... Show moreRecent models hypothesize that adolescents' risky behavior is the consequence of increased sensitivity to rewards in the ventral medial (VM) prefrontal cortex (PFC) and the ventral striatum (VS), paired with immature cognitive control abilities due to slow maturation of the dorsal anterior cingulate cortex (ACC) and lateral PFC. We tested this hypothesis with fMRI using a gambling task in which participants chose between Low-Risk gambles with a high probability of obtaining a small reward (1 Euro) and High-Risk gambles with a smaller probability of obtaining a higher reward (2, 4, 6, or 8 Euro). We examined neural responses during choice selection and outcome processing in participants from 4 age groups (pre-pubertal children, early adolescents, older adolescents and young adults). High-Risk choices increased with rewards for all ages, but risk-taking decreased with age for low reward gambles. The fMRI results confirmed that High-Risk choices were associated with activation in VMPFC, whereas Low-Risk choices were associated with activation in lateral PFC. Activation in dorsal ACC showed a linear decrease with age, whereas activation in VMPFC and VS showed an inverted U-shaped developmental pattern, with a peak in adolescence. In addition, behavioral differences in risk-taking propensity modulated brain activation in all age groups. These findings support the hypothesis that risky behavior in adolescence is associated with an imbalance caused by different developmental trajectories of reward and regulatory brain circuitry. (C) 2010 Elsevier Inc. All rights reserved. Show less
