Individual differences in children's comprehension of temporal relations: Dissociable contributions of working memory capacity and working memory updating.

In two experiments, we examined 9- to 12-year-old children's comprehension and processing of two-clause sentences with a temporal connective (before or after) in the sentence-medial or sentence-initial position. We obtained measures of individual differences in working memory (WM) capacity and WM updating to test their contributions to comprehension. We measured the accuracy of children's responses to the questions "What happened first?" (Experiment 1; N = 74) and "What happened last?" (Experiment 2; N = 50) as well as their sentence reading times. Together, these experiments show continued development of comprehension of temporal relations in children in upper elementary school and suggest that children's comprehension difficulties (i.e., more comprehension errors and longer reading times) were influenced by clause salience and recency effects rather than sentence chronology or the familiarity of the connective. Our findings are consistent with a memory resource-limited account and suggest that individual differences in WM updating and WM capacity make dissociable contributions to processing and comprehension of sentences with temporal order information.

Hanging Out With the Right Crowd: Peer Influence on Risk-Taking Behavior in Adolescence.

Peer influence plays a key role in the increase of risk-taking behavior during adolescence. However, its underlying processes are not fully understood. This study examined the effects of social norms, conveyed through peer advice, on risk-taking behavior in 15- to 17-year-old adolescents (N = 76). Participants played a card-guessing task alone and with online peer advice. Results showed that risk-taking increased in the presence of peers. The results further showed that adolescents took into account the uncertainty associated with gambles, as well as the social norms conveyed by peers. Our findings suggest that peers are most influential in uncertain situations and demonstrate the value of a social norms approach in examining the processes underlying peer effects.

Behavioral and neural correlates of loss aversion and risk avoidance in adolescents and adults.

Individuals are frequently faced with risky decisions involving the potential for both gain and loss. Exploring the role of both potential gains and potential losses in predicting risk taking is critical to understanding how adolescents and adults make the choice to engage in or avoid a real-life risk. This study aimed to examine the impact of potential losses as well as gains on adolescent decisions during risky choice in a laboratory task. Adolescent (n=18) and adult (n=16) participants underwent functional magnetic resonance imaging (fMRI) during a mixed gambles task, and completed questionnaires measuring real-world risk-taking behaviors. While potential loss had a significantly greater effect on choice than potential gain in both adolescents and adults and there were no behavioral group differences on the task, adolescents recruited significantly more frontostriatal circuitry than adults when choosing to reject a gamble. During risk-seeking behavior, adolescent activation in medial prefrontal cortex (mPFC) was negatively correlated with self-reported likelihood of risk taking. During risk-avoidant behavior, mPFC activation of in adults was negatively correlated with self-reported benefits of risk-taking. Taken together, these findings reflect different neural patterns during risk-taking and risk-avoidant behaviors in adolescents and adults.

Considerations for imaging the adolescent brain.

In recent years the number of functional neuroimaging studies on adolescence has exploded. These studies have led to important new insights about the relation between functional brain development and behavior. However, special consideration is warranted when working with adolescents. In this review, we review variables, including pubertal stage, sleep patterns and pregnancy, which are particularly relevant for developmental cognitive neuroscience studies involving adolescents. Consideration of the unique challenges associated with adolescence will help the growing field of developmental neuroimaging standardize procedures and will eventually facilitate interpretation across studies.

Do you like me? Neural correlates of social evaluation and developmental trajectories.

Social acceptance is of key importance for healthy functioning. We used functional magnetic resonance imaging (fMRI) to examine age-related changes in the neural correlates of social acceptance and rejection processing. Participants from four age groups participated in the study: pre-pubertal children (8-10 years), early adolescents (12-14 years), older adolescents (16-17 years) and young adults (19-25 years). During the experiment, participants were presented with unfamiliar faces of peers and were asked to predict whether they expected to be liked or disliked by the other person, followed by feedback indicating acceptance or rejection. Results showed that activation in the ventral mPFC and striatum to social feedback was context-dependent; there was increased activation when participants had positive expectations about social evaluation, and increased activation following social acceptance feedback. Age-related comparisons revealed a linear increase in activity with age in these brain regions for positive expectations of social evaluation. Similarly, a linear increase with age was found for activation in the striatum, ventral mPFC, OFC, and lateral PFC for rejection feedback. No age-related differences in neural activation were shown for social acceptance feedback. Together, these results provide important insights in the developmental trajectories of brain regions implicated in social and affective behavior.

Adolescent risky decision-making: neurocognitive development of reward and control regions.

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), 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.

What motivates the adolescent? Brain regions mediating reward sensitivity across adolescence.

The relation between brain development across adolescence and adolescent risky behavior has attracted increasing interest in recent years. It has been proposed that adolescents are hypersensitive to reward because of an imbalance in the developmental pattern followed by the striatum and prefrontal cortex. To date, it is unclear if adolescents engage in risky behavior because they overestimate potential rewards or respond more to received rewards and whether these effects occur in the absence of decisions. In this study, we used a functional magnetic resonance imaging paradigm that allowed us to dissociate effects of the anticipation, receipt, and omission of reward in 10- to 12-year-old, 14- to 15-year-old, and 18- to 23-year-old participants. We show that in anticipation of uncertain outcomes, the anterior insula is more active in adolescents compared with young adults and that the ventral striatum shows a reward-related peak in middle adolescence, whereas young adults show orbitofrontal cortex activation to omitted reward. These regions show distinct developmental trajectories. This study supports the hypothesis that adolescents are hypersensitive to reward and adds to the current literature in demonstrating that neural activation differs in adolescents even for small rewards in the absence of choice. These findings may have important implications for understanding adolescent risk-taking behavior.

Neurocognitive development of relational reasoning.

Relational reasoning is an essential component of fluid intelligence, and is known to have a protracted developmental trajectory. To date, little is known about the neural changes that underlie improvements in reasoning ability over development. In this event-related functional magnetic resonance imaging (fMRI) study, children aged 8-12 and adults aged 18-25 performed a relational reasoning task adapted from Raven's Progressive Matrices. The task included three levels of relational reasoning demands: REL-0, REL-1, and REL-2. Children exhibited disproportionately lower accuracy than adults on trials that required integration of two relations (REL-2). Like adults, children engaged lateral prefrontal cortex (PFC) and parietal cortex during task performance; however, they exhibited different time courses and activation profiles, providing insight into their approach to the problems. As in prior studies, adults exhibited increased rostrolateral PFC (RLPFC) activation when relational integration was required (REL-2 > REL-1, REL-0). Children also engaged RLPFC most strongly for REL-2 problems at early stages of processing, but this differential activation relative to REL-1 trials was not sustained throughout the trial. These results suggest that the children recruited RLPFC while processing relations, but failed to use it to integrate across two relations. Relational integration is critical for solving a variety of problems, and for appreciating analogies; the current findings suggest that developmental improvements in this function rely on changes in the profile of engagement of RLPFC, as well as dorsolateral PFC and parietal cortex.

Neural mechanisms supporting flexible performance adjustment during development.

Feedback processing is crucial for successful performance adjustment following changing task demands. The present event-related fMRI study was aimed at investigating the developmental differences in brain regions associated with different aspects of feedback processing. Children age 8-11, adolescents age 14-15, and adults age 18-24 performed a rule switch task resembling the Wisconsin Card Sorting Task, and analyses focused on different types of negative and positive feedback. All age groups showed more activation in lateral orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), and superior parietal cortex following negative relative to positive performance feedback, but the regions contributed to different aspects of feedback processing and had separable developmental trajectories. OFC was adultlike by age 8-11, whereas parietal cortex was adultlike by age 14-15. DLPFC and ACC, in contrast, were still developing after age 14-15. These findings demonstrate that changes in separable neural systems underlie developmental differences in flexible performance adjustment. Supplementary data from this study are available online at the Psychonomic Society Archive of Norms, Stimuli, and Data, at www.psychonomic.org/archive.

A developmental study of risky decisions on the cake gambling task: age and gender analyses of probability estimation and reward evaluation.

Decision making, or the process of choosing between competing courses of actions, is highly sensitive to age-related change, showing development throughout adolescence. In this study, we tested whether the development of decision making under risk is related to changes in risk-estimation abilities. Participants (N = 93) between ages 8-30 performed a child friendly gambling task, the Cake Gambling task, which was inspired by the Cambridge Gambling Task (Rogers et al., 1999), which has previously been shown to be sensitive to orbitofrontal cortex (OFC) damage. The task allowed comparisons of the contributions to risk perception of (1) the ability to estimate probabilities and (2) evaluate rewards. Adult performance patterns were highly similar to those found in previous reports, showing increased risk taking with increases in the probability of winning and the magnitude of potential reward. Behavioral patterns in children and adolescents did not differ from adult patterns, showing a similar ability for probability estimation and reward evaluation. These data suggest that participants 8 years and older perform like adults in a gambling task, previously shown to depend on the OFC in which all the information needed to make an advantageous decision is given on each trial and no information needs to be inferred from previous behavior. Interestingly, at all ages, females were more risk-averse than males. These results suggest that the increase in real-life risky behavior that is seen in adolescence is not a consequence of changes in risk perception abilities. The findings are discussed in relation to theories about the protracted development of the prefrontal cortex.

Developmental trends for object and spatial working memory: a psychophysiological analysis.

This study examined developmental trends in object and spatial working memory (WM) using heart rate (HR) to provide an index of covert cognitive processes. Participants in 4 age groups (6-7, 9-10, 11-12, 18-26, n=20 each) performed object and spatial WM tasks, in which each trial was followed by feedback. Spatial WM task performance reached adult levels before object WM task performance. The differential developmental trends for object and spatial WM found in this study are taken to suggest that these WM components are separable. Negative performance feedback elicited HR slowing that was more pronounced for adults than for children. The development of performance monitoring as indexed by covert HR slowing following performance feedback contributes to WM performance.

Neurocognitive development of the ability to manipulate information in working memory.

The ability to manipulate information in working memory is a key factor in cognitive development. Here, we used event-related functional MRI to test the hypothesis that developmental improvements in manipulation, relative to pure maintenance, are associated with increased recruitment of dorsolateral (DL) prefrontal cortex (PFC) and superior parietal cortex. Three age groups (8-12 years old, 13-17 years old, and 18-25 years old) performed an object-working memory task with separate maintenance and manipulation conditions. We found that 8- to 12-year-olds did not perform the task as well as adolescents or adults, particularly on trials requiring manipulation in addition to maintenance. In this study, no age differences were observed in the activation profile of ventrolateral PFC, a region associated with online maintenance. In contrast, unlike the older participants, 8- to 12-year-olds failed to recruit right DL PFC and bilateral superior parietal cortex during the delay period for manipulation relative to maintenance. This group difference was observed specifically during the delay period, while participants reordered items in working memory, and could not be accounted for by group differences in performance. Across participants, activation levels in right DL PFC and superior parietal cortex, but not ventrolateral PFC, were positively correlated with performance on manipulation trials. These results indicate that increased recruitment of right DL PFC and bilateral parietal cortex during adolescence is associated with improvements in the ability to work with object representations.

Neural correlates of developmental differences in risk estimation and feedback processing.

The primary aim of this study was to compare the neural substrates of decision-making in middle-aged children and adults. To this end, we collected fMRI data while 9-12-year-olds and 18-26-year-olds performed a simple gambling task. The task was designed to tap two important aspects of decision-making: risk estimation and feedback processing. We examined how orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex (DLPFC) contributed to risk estimation, and how ventrolateral and medial prefrontal cortices (VLPFC and medial PFC) contributed to negative feedback processing in children and adults. Region of interest analyses revealed differences in brain activation between children and adults for ACC and lateral OFC. ACC was recruited more for high-risk than for low-risk trials, and this difference was larger for children than for adults. In contrast, children and adults did not differ in activation for OFC or DLPFC. These data suggest that children's decision-making under uncertainty is associated with a high degree of response conflict. Both age groups exhibited bilateral VLPFC (BA 47) and medial PFC/ACC (BA 6/ BA 32 (dorsal) and 24 (ventral)) activation associated with negative feedback processing. Relative to adults, children engaged lateral OFC more strongly for negative relative to positive feedback. These results indicate that children may find negative feedback more aversive than adults do. In summary, children aged 9-12 years and adults recruit similar brain regions during risk-estimation and feedback processing, but some key differences between the groups provide insight into the factors contributing to developmental changes in decision-making.