The adolescent brain: insights from functional neuroimaging research

The relationship between negative life events and cortical structural connectivity in adolescents

Adolescence is a crucial period for physical and psychological development. The impact of negative life events represents a risk factor for the onset of neuropsychiatric disorders. This study aims to investigate the relationship between negative life events and structural brain connectivity, considering both graph theory and connectivity strength. A group (n = 487) of adolescents from the IMAGEN Consortium was divided into Low and High Stress groups. Brain networks were extracted at an individual level, based on morphological similarity between grey matter regions with regions defined using an atlas-based region of interest (ROI) approach. Between-group comparisons were performed with global and local graph theory measures in a range of sparsity levels. The analysis was also performed in a larger sample of adolescents (n = 976) to examine linear correlations between stress level and network measures. Connectivity strength differences were investigated with network-based statistics. Negative life events were not found to be a factor influencing global network measures at any sparsity level. At local network level, between-group differences were found in centrality measures of the left somato-motor network (a decrease of betweenness centrality was seen at sparsity 5%), of the bilateral central visual and the left dorsal attention network (increase of degree at sparsity 10% at sparsity 30% respectively). Network-based statistics analysis showed an increase in connectivity strength in the High stress group in edges connecting the dorsal attention, limbic and salience networks. This study suggests negative life events alone do not alter structural connectivity globally, but they are associated to connectivity properties in areas involved in emotion and attention.

Patterns of service utilization among youth with substance use service need: a cohort study

BACKGROUND

Integrated youth services (IYS) are vital to addressing the needs of youth who use substances. Evidence on the characteristics of youths accessing these services and the types of services accessed have been limited. The objectives were to identify sociodemographic, self-reported health and mental health, patterns of service utilization (service type and frequency of visits) among youths with different levels of substance use service needs (low, moderate, and high), and to estimate the extent to which substance use service needs, self-reported health and mental health influenced the frequency of visits and types of service utilized.

METHODS

Data were collected from youth (12-24 years) accessing IYS centres in Canada. Information on socio-demographic factors, substance use in the last month, self-rated health measures, number of service visits, and type of services utilized were included. Poisson regression was used to estimate the relationship between substance use needs and number of service visits and the different type of services utilized.

RESULTS

Of 6181 youths, 48.0% were categorized as low substance use service needs, 30.6% had moderate needs and 21.4% had high needs, with higher proportion of men in the high needs group. Mental health and substance use (MHSU) services were utilized the most across all three groups, followed by counseling. The median number of visits was 4 for the low and moderate needs group and 5 in the high needs group. People with high service needs had 10% higher rate of service visits and utilized 10% more services than people with low service needs (service visits: RR = 1.1 (95%CI: 1.1-1.2); service type: RR = 1.1 (95%CI:1.0-1.1)). The rate of service visits increased by 30 to 50% and the number of services increased by 10-20% for people who rated their health good/fair/poor. Similarly, the rate of service visits increased by 40 to 60% and the number of services increased by 20% for people who rated their mental health good/fair/poor.

CONCLUSIONS AND IMPACTS

Our study highlighted that regardless of service needs, youth who use alcohol and drugs have complex intersecting needs that present once they access integrated youth services.

Relationship between gamer profiles, gaming behavior, sociodemographic characteristics, and big five personality traits among French law students

BACKGROUND

Over the past 10 years, gamer profiles have been developed to understand the reason underlying players' intrinsic motivation. While the research undertaken has led to the creation of distinct models (e.g., BrainHex and Hexad typologies), there is a lack of studies on the prevalence of these profiles among a specific population and the association between the target population's profiles and their personality traits, gaming behavior, and sociodemographic characteristics.

METHODS

Thus, the present study aimed to (a) establish the gamer profiles of French undergraduate law students, (b) examine the relationships between the participants' profiles and their personality traits, gaming behavior, and sociodemographic characteristics, with a view to the development of serious games specifically intended for this population. In total, 753 French undergraduate students participated in the study, completing an online questionnaire. Data were analyzed using Latent Profile Analysis (LPA), chi-square, and ANOVA.

RESULTS

The main findings show that among participants, the two most prevalent gamers' profiles are Mastermind (45%) and Seeker (22.7%); followed by three less represented archetypes: Conqueror (12.9%), Daredevil (9.7%), and Achiever (9.7%). These archetypes are associated with the participants' Big Five personality traits. Specifically, Daredevils, Masterminds, and Seekers have high mean scores on Extraversion (p < .001); Achievers and Seekers have high mean scores on Agreeableness (p < .001); Seekers and Achievers have high mean scores on Neuroticism (p < .001); and Seekers, Masterminds, and Achievers have high mean scores on Openness (p < .001). The unveiled profiles are also significantly associated with the participants' gaming behavior including their playing frequency (p < .001), game types (p = .031), and sociodemographic characteristics (p < .001). For example, Masterminds are more likely to be female than the other four profiles (p < .001), while Conquerors and Daredevils are more likely to have a low socio-economic status compared to those with intermediate and high socio-economic status (p = .49).

CONCLUSION

These findings can be used to design serious/educational games tailored to the studied population.

Behavioral Responses to Sucrose as an Indicator of Positive Hedonic Response Across the First Six Months of Infancy

Behavioral responses to sucrose provide an index of positive hedonic response in newborns. In 118 infants, the current study used repeated assessments to explore behavioral responses to sucrose solutions (24%/50% sucrose) compared to water across the first six months of infancy. Lip smacking and bringing fingers to mouth are more likely to occur in response to 24% sucrose relative to water. Tongue protrusions are also more likely to occur for 50% sucrose relative to water. Behavioral responses to sucrose may provide an index of positive hedonic response and could be used to investigate individual differences in the first six months of infancy.

Functional MRI investigation of verbal working memory in adults with anorexia nervosa

Literature regarding verbal working memory (vWM) in anorexia nervosa (AN) has been inconsistent due to a misunderstanding of the key components of vWM and introduction of confounding stimuli. Furthermore, there are no studies looking at how brain function in people with AN relates to vWM performance. The present study used functional magnetic resonance imaging (fMRI) with a letter n-back paradigm to study the effect of increasing vWM task difficulty on cortical functioning in the largest AN sample to date (n = 31). Although the AN group had low BMI and higher anxious and depressive symptomology compared to age-matched controls (HC), there were no between-group differences in accuracy and speed at any task difficulty. fMRI data revealed no regions exhibiting significant differences in activation when groups were compared at each difficulty separately and no regions showing group x condition interaction. Although there was a trend towards lower accuracy as duration of illness increased, this was not correlated with activity in regions associated with vWM. These findings indicate that vWM in AN is as efficient and performed using the same cognitive strategy as HC, and that there may not be a need for therapies to pursue remediation of this particular neurocognitive faculty.

Brain and Cognitive Development in Adolescents with Anorexia Nervosa: A Systematic Review of fMRI Studies

Anorexia nervosa (AN) is an eating disorder often occurring in adolescence. AN has one of the highest mortality rates amongst psychiatric illnesses and is associated with medical complications and high risk for psychiatric comorbidities, persisting after treatment. Remission rates range from 23% to 33%. Moreover, weight recovery does not necessarily reflect cognitive recovery. This issue is of particular interest in adolescence, characterized by progressive changes in brain structure and functional circuitries, and fast cognitive development. We reviewed existing literature on fMRI studies in adolescents diagnosed with AN, following PRISMA guidelines. Eligible studies had to: (1) be written in English; (2) include only adolescent participants; and (3) use block-design fMRI. We propose a pathogenic model based on normal and AN-related neural and cognitive maturation during adolescence. We propose that underweight and delayed puberty-caused by genetic, environmental, and neurobehavioral factors-can affect brain and cognitive development and lead to impaired cognitive flexibility, which in turn sustains the perpetuation of aberrant behaviors in a vicious cycle. Moreover, greater punishment sensitivity causes a shift toward punishment-based learning, leading to greater anxiety and ultimately to excessive reappraisal over emotions. Treatments combining physiological and neurobehavioral rationales must be adopted to improve outcomes and prevent relapses.

Occlusal force predicts global motion coherence threshold in adolescent boys

Background

Beneficial effects of mastication on cognitive abilities in the elderly have been shown in human studies. However, little is currently known about the effect of masticatory stimulation on cognitive and perceptual ability in younger populations. The purpose of the present study is to investigate the influences of masticatory stimulation on perceptual ability in adolescent boys.

Methods

The present study examined the relationship between occlusal force (i.e., masticatory stimulation) and visual perception ability in adolescent boys. Visual perception ability was quantified by measuring global motion coherence threshold using psychophysical method. As an index of masticatory stimulation, occlusal force was measured by pressure sensitive film. We also measured participants’ athletic ability, e.g. aerobic capacity and grip strength, as potential confounding factor.

Results

The multiple regression analysis revealed a significant negative correlation between global motion coherence threshold and occlusal force, which persisted after controlling for confounding factors such as age and aerobic capacity.

Conclusions

This finding indicates that masticatory stimulation enhances visual perception in adolescent boys, indicating the possibility that beneficial effects of masticatory stimulation are observed not only in the elderly but in developing population consistently with the findings of the previous animal studies.

The development of functional network organization in early childhood and early adolescence: A resting-state fNIRS study

Early childhood (7–8 years old) and early adolescence (11–12 years old) constitute two landmark developmental stages that comprise considerable changes in neural cognition. However, very limited information from functional neuroimaging studies exists on the functional topological configuration of the human brain during specific developmental periods. In the present study, we utilized continuous resting-state functional near-infrared spectroscopy (rs-fNIRS) imaging data to examine topological changes in network organization during development from early childhood and early adolescence to adulthood. Our results showed that the properties of small-worldness and modularity were not significantly different across development, demonstrating the developmental maturity of important functional brain organization in early childhood. Intriguingly, young children had a significantly lower global efficiency than early adolescents and adults, which revealed that the integration of the distributed networks strengthens across the developmental stages underlying cognitive development. Moreover, local efficiency of young children and adolescents was significantly lower than that of adults, while there was no difference between these two younger groups. This finding demonstrated that functional segregation remained relatively steady from early childhood to early adolescence, and the brain in these developmental periods possesses no optimal network configuration. Furthermore, we found heterogeneous developmental patterns in the regional nodal properties in various brain regions, such as linear increased nodal properties in the frontal cortex, indicating increasing cognitive capacity over development. Collectively, our results demonstrated that significant topological changes in functional network organization occurred during these two critical developmental stages, and provided a novel insight into elucidating subtle changes in brain functional networks across development.

Chronic Stress in Adolescents and Its Neurobiological and Psychopathological Consequences: An RDoC Perspective

The Research Domain Criteria (RDoC) initiative provides a strategy for classifying psychopathology based on behavioral dimensions and neurobiological measures. Neurodevelopment is an orthogonal dimension in the current RDoC framework; however, it has not yet been fully incorporated into the RDoC approach. A combination of both a neurodevelopmental and RDoC approach offers a multidimensional perspective for understanding the emergence of psychopathology during development. Environmental influence (e.g., stress) has a profound impact on the risk for development of psychiatric illnesses. It has been shown that chronic stress interacts with the developing brain, producing significant changes in neural circuits that eventually increase the susceptibility for development of psychiatric disorders. This review highlights effects of chronic stress on the adolescent brain, as adolescence is a period characterized by a combination of significant brain alterations, high levels of stress, and emergence of psychopathology. The literature synthesized in this review suggests that chronic stress-induced changes in neurobiology and behavioral constructs underlie the shared vulnerability across a number of disorders in adolescence. The review particularly focuses on depression and substance use disorders; however, a similar argument can also be made for other psychopathologies, including anxiety disorders. The summarized findings underscore the need for a framework to integrate neurobiological findings from disparate psychiatric disorders and to target transdiagnostic mechanisms across disorders.

Lower total and regional grey matter brain volumes in youth with perinatally-acquired HIV infection: Associations with HIV disease severity, substance use, and cognition

Despite improved survival due to combination antiretroviral therapy (cART), youth with perinatally-acquired HIV (PHIV) show cognitive deficits and developmental delay at increased rates. HIV affects the brain during critical periods of development, and the brain may be a persistent reservoir for HIV due to suboptimal blood brain barrier penetration of cART. We conducted structural magnetic resonance imaging (sMRI) and cognitive testing in 40 PHIV youth (mean age=16.7years) recruited from the NIH Pediatric HIV/AIDS Cohort Study (PHACS) who are part of the first generation of PHIV youth surviving into adulthood. Historical and current HIV disease severity and substance use measures were also collected. Total and regional cortical grey matter brain volumes were compared to a group of 334 typically-developing, HIV-unexposed and uninfected youth (frequency-matched for age and sex) from the Pediatric Imaging, Neurocognition, and Genetics (PING) study (mean age=16.1years). PHIV youth had smaller (2.8-5.1%) total and regional grey matter volumes than HIV-unexposed and uninfected youth, with smallest volumes seen among PHIV youth with higher past peak viral load (VL) and recent unsuppressed VL. In PHIV youth, worse cognitive performance correlated with smaller volumes. This pattern of smaller grey matter volumes suggests that PHIV infection may influence brain development and underlie cognitive dysfunction seen in this population. Among PHIV youth, smaller volumes were also linked to substance use (alcohol use: 9.0-13.4%; marijuana use: 10.1-16.0%). In this study, collection of substance use information was limited to the PHIV cohort; future studies should also collect substance use information in controls to further address interactions between HIV and substance use on brain volume.

Striatum on the anxiety map: Small detours into adolescence

Adolescence is the most sensitive period for the development of pathological anxiety. Moreover, specific neural changes associated with the striatum might be related to adolescent vulnerability to anxiety. Up to now, the study of anxiety has primarily focused on the amygdala, bed nucleus of the stria terminalis (BNST), hippocampus and ventromedial prefrontal cortex (vmPFC), while the striatum has typically not been considered as part of the anxiety system. This review proposes the addition of the striatum, a complex, multi-component structure, to the anxiety network by underscoring two lines of research. First, the co-occurrence of the adolescent striatal development with the peak vulnerability of adolescents to anxiety disorders might potentially reflect a causal relationship. Second, the recognition of the role of the striatum in fundamental behavioral processes that do affect anxiety supports the putative importance of the striatum in anxiety. These behavioral processes include (1) attention, (2) conditioning/prediction error, and (3) motivation. This review proposes a simplistic schematic representation of the anxiety circuitry that includes the striatum, and aims to promote further work in this direction, as the role of the striatum in shaping an anxiety phenotype during adolescence could have critical implications for understanding and preventing the peak onset of anxiety disorders during this period. This article is part of a Special Issue entitled SI: Adolescent plasticity.

Neurobiological signatures associated with alcohol and drug use in the human adolescent brain

Magnetic resonance (MR) techniques provide opportunities to non-invasively characterize neurobiological milestones of adolescent brain development. Juxtaposed to the critical finalization of brain development is initiation of alcohol and substance use, and increased frequency and quantity of use, patterns that can lead to abuse and addiction. This review provides a comprehensive overview of existing MR studies of adolescent alcohol and drug users. The most common alterations reported across substance used and MR modalities are in the frontal lobe (63% of published studies). This is not surprising, given that this is the last region to reach neurobiological adulthood. Comparatively, evidence is less consistent regarding alterations in regions that mature earlier (e.g., amygdala, hippocampus), however newer techniques now permit investigations beyond regional approaches that are uncovering network-level vulnerabilities. Regardless of whether neurobiological signatures exist prior to the initiation of use, this body of work provides important direction for ongoing prospective investigations of adolescent brain development, and the significant impact of alcohol and substance use on the brain during the second decade of life.

Sex differences in behavior and neural development and their role in adolescent vulnerability to substance use

Adolescents are especially prone to risky behavior and to the emergence of psychological disorders like substance abuse, anxiety and depression. However, there is a sex (or gender) difference in this vulnerability, with females being more prone to developing internalizing disorders and males being more likely to engage in risky behavior and drug use. While several researchers have proposed that there is a relationship between corticolimbic circuit development and adolescent vulnerability, the current proposed models do not take sex differences into account. In this review, we explore recent findings from both human and rodent studies of sex differences during adolescence. In particular, we consider epidemiological studies on the factors that contribute to the development of substance abuse and internalizing disorders, laboratory studies on reward-related and decision-making behavior, and neuroanatomical studies on the development of several structures in the corticolimbic circuit (i.e., prefrontal cortex [PFC], amygdala and striatum). We then integrate these recent findings into models of adolescent vulnerability to substance use that have previously not addressed sex differences. Lastly, we discuss methodological considerations for the interpretation and design of studies on sex (or gender) differences during adolescence while highlighting some opportunities for future investigations.

fMRI investigation of response inhibition, emotion, impulsivity, and clinical high-risk behavior in adolescents

High-risk behavior in adolescents is associated with injury, mental health problems, and poor outcomes in later life. Improved understanding of the neurobiology of high-risk behavior and impulsivity shows promise for informing clinical treatment and prevention as well as policy to better address high-risk behavior. We recruited 21 adolescents (age 14–17) with a wide range of high-risk behavior tendencies, including medically high-risk participants recruited from psychiatric clinics. Risk tendencies were assessed using the Adolescent Risk Behavior Screen (ARBS). ARBS risk scores correlated highly (0.78) with impulsivity scores from the Barratt Impulsivity scale (BIS). Participants underwent 4.7 Tesla functional magnetic resonance imaging (fMRI) while performing an emotional Go/NoGo task. This task presented an aversive or neutral distractor image simultaneously with each Go or NoGo stimulus. Risk behavior and impulsivity tendencies exhibited similar but not identical associations with fMRI activation patterns in prefrontal brain regions. We interpret these results as reflecting differences in response inhibition, emotional stimulus processing, and emotion regulation in relation to participant risk behavior tendencies and impulsivity levels. The results are consistent with high impulsivity playing an important role in determining high risk tendencies in this sample containing clinically high-risk adolescents.

Feasibility of functional neuroimaging to understand adolescent women's sexual decision making

PURPOSE

For young women, new sexual experiences normatively increase after puberty and coincide with extensive changes to brain regions governing self-regulation of risk behavior. These neurodevelopmental changes could leave some young women vulnerable for negative sexual outcomes, including sexually transmitted infection and unintended pregnancy. We evaluated the feasibility of using functional neuroimaging to understand the sexual decision making of adolescent women.

METHODS

Adolescent women (N = 14; 14-15 years) completed enrollment interviews, a neuroimaging task gauging neural activation to appetitive stimuli, and 30 days of prospective diaries following the scan characterizing daily affect and sexual behaviors. Descriptive and inferential statistics assessed the association between imaging and behavioral data.

RESULTS

Young women were highly compliant with neuroimaging and diary protocol. Neural activity in a cognitive-affective network, including prefrontal and anterior cingulate regions, was significantly greater during low-risk decisions. Compared with other decisions, high-risk sexual decisions elicited greater activity in the anterior cingulate, and low-risk sexual decision elicited greater activity in regions of the visual cortex. Young women's sexual decision ratings were linked to their sexual history characteristics and daily self-reports of sexual emotions and behaviors.

CONCLUSIONS

It is feasible to recruit and retain a cohort of female participants to perform a functional magnetic resonance imaging task focused on making decisions about sex, on the basis of varying levels of hypothetical sexual risk, and to complete longitudinal prospective diaries following this task. Preliminary evidence suggests that risk level differentially impacts brain activity related to sexual decision making in these women, which may be related to past and future sexual behaviors.

Neural correlates of high-risk behavior tendencies and impulsivity in an emotional Go/NoGo fMRI task

Improved neuroscientific understanding of high-risk behaviors such as alcohol binging, drug use, and unsafe sex will lead to therapeutic advances for high-risk groups. High-risk behavior often occurs in an emotionally-charged context, and behavioral inhibition and emotion regulation play important roles in risk-related decision making. High impulsivity is an important potential contributor to high-risk behavior tendencies. We explored the relationships between high-risk behavior tendencies, impulsivity, and fMRI brain activations in an emotional Go/NoGo task. This task presented emotional distractor pictures (aversive vs. neutral) simultaneously with Go/NoGo stimuli (square vs. circle) that required a button press or withholding of the press, respectively. Participants' risk behavior tendencies were assessed with the Cognitive Appraisal of Risky Events (CARE) scale. The Barratt Impulsivity Scale 11 (BIS) was used to assess participant impulsivity. Individuals with higher CARE risk scores exhibited reduced activation related to response inhibition (NoGo-Go) in right orbital frontal cortex (OFC) and ventromedial prefrontal cortex. These regions did not show a significant relationship with impulsivity scores. Conversely, more impulsive individuals showed reduced emotion-related activity (aversive-neutral distractors) in dorsomedial prefrontal cortex, perigenual anterior cingulate cortex, and right posterior OFC. There were distinct neural correlates of high-risk behavior tendency and impulsivity in terms of brain activity in the emotional Go/NoGo task. This dissociation supports the conception of high-risk behavior tendency as a distinct construct from that of impulsivity. Our results suggest that treatment for high-risk behavior may be more effective with a nuanced approach that does not conflate high impulsivity necessarily with high-risk behavior tendencies.

fMRI functional connectivity applied to adolescent neurodevelopment

The exponential rise in the number of functional brain connectivity studies, particularly those examining intrinsic functional connectivity (iFC) at rest, and the promises of this work for unraveling the ontogeny of functional neural systems motivate this review. Shortly before this explosion in functional connectivity research, developmental neuroscientists had proposed theories based on neural systems models to explain behavioral changes, particularly in adolescence. The current review presents recent advances in imaging in brain connectivity research, which provides a unique tool for the study of neural systems. Understanding the potential of neuroimaging for refining neurodevelopmental models of brain function requires a description of various functional connectivity approaches. In this review, we describe task-based and resting-state functional magnetic resonance imaging (fMRI) analytic strategies, but we focus on iFC findings from resting-state data to describe general developmental trajectories of brain network organization. Finally, we use the example of drug addiction to frame a discussion of psychopathology that emerges in adolescence.

Self-disturbances as a possible premorbid indicator of schizophrenia risk: a neurodevelopmental perspective

Self-disturbances (SDs) are increasingly identified in schizophrenia and are theorized to confer vulnerability to psychosis. Neuroimaging research has shed some light on the neural correlates of SDs in schizophrenia. But, the onset and trajectory of the neural alterations underlying SDs in schizophrenia remain incompletely understood. We hypothesize that the aberrant structure and function of brain areas (e.g., prefrontal, lateral temporal, and parietal cortical structures) comprising the "neural circuitry of self" may represent an early, premorbid (i.e., pre-prodromal) indicator of schizophrenia risk. Consistent with neurodevelopmental models, we argue that "early" (i.e., perinatal) dysmaturational processes (e.g., abnormal cortical neural cell migration and mini-columnar formation) affecting key prefrontal (e.g., medial prefrontal cortex), lateral temporal cortical (e.g., superior temporal sulcus), and parietal (e.g., inferior parietal lobule) structures involved in self-processing may lead to subtle disruptions of "self" during childhood in persons at risk for schizophrenia. During adolescence, progressive neurodevelopmental alterations (e.g., aberrant synaptic pruning) affecting the neural circuitry of self may contribute to worsening of SDs. This could result in the emergence of prodromal symptoms and, eventually, full-blown psychosis. To highlight why adolescence may be a period of heightened risk for SDs, we first summarize the literature regarding the neural correlates of self in typically developing children. Next, we present evidence from neuroimaging studies in genetic high-risk youth suggesting that fronto-temporal-parietal structures mediating self-reflection may be abnormal in the premorbid period. Our goal is that the ideas presented here might provide future directions for research into the neurobiology of SDs during the pre-psychosis development of youth at risk for schizophrenia.

Gray Matter Alterations in Schizophrenia High-Risk Youth and Early-Onset Schizophrenia: A Review of Structural MRI Findings

This article reviews the literature on structural magnetic resonance imaging findings in pediatric and young adult populations at clinical or genetic high-risk for schizophrenia and early-onset schizophrenia. The implications of this research are discussed for understanding the pathophysiology of schizophrenia and for early intervention strategies. The evidence linking brain structural changes in prepsychosis development and early-onset schizophrenia with disruptions of normal neurodevelopmental processes during childhood or adolescence is described. Future directions are outlined for research to address knowledge gaps regarding the neurobiological basis of brain structural abnormalities in schizophrenia and to improve the usefulness of these abnormalities for preventative interventions.

Different developmental trajectories for anticipation and receipt of reward during adolescence

Typical adolescent behaviour such as increased risk-taking and novelty-seeking is probably related to developmental changes in the brain reward system. This functional MRI study investigated how brain activation related to two components of reward processing (Reward Anticipation and Reward Outcome) changes with age in a sample of 39 children, adolescents and young adults aged 10-25. Our data revealed age-related changes in brain activity during both components of reward processing. Activation related to Reward Anticipation increased with age, while activation related to Reward Outcome decreased in various regions of the reward network. This shift from outcome to anticipation was confirmed by subsequent analyses showing positive correlations between age and the difference in activation between Reward Anticipation and Reward Outcome. The shift was predominantly present in striatal regions and was accompanied by a significant effect of age on behaviour, with older participants showing more response speeding on potentially rewarding trials than younger participants. This study provides evidence for functional changes in the reward system which may underlie typical adolescent behaviour.

Ongoing neural development of affective theory of mind in adolescence

Affective Theory of Mind (ToM), an important aspect of ToM, involves the understanding of affective mental states. This ability is critical in the developmental phase of adolescence, which is often related with socio-emotional problems. Using a developmentally sensitive behavioral task in combination with functional magnetic resonance imaging, the present study investigated the neural development of affective ToM throughout adolescence. Eighteen adolescent (ages 12-14 years) and 18 young adult women (aged 19-25 years) were scanned while evaluating complex affective mental states depicted by actors in video clips. The ventromedial prefrontal cortex (vmPFC) showed significantly stronger activation in adolescents in comparison to adults in the affective ToM condition. Current results indicate that the vmPFC might be involved in the development of affective ToM processing in adolescence.

Stress and the developing adolescent brain

Adolescence is a time of continued brain maturation, particularly in limbic and cortical regions, which undoubtedly plays a role in the physiological and emotional changes coincident with adolescence. An emerging line of research has indicated that stressors experienced during this crucial developmental stage may affect the trajectory of this neural maturation and contribute to the increase in psychological morbidities, such as anxiety and depression, often observed during adolescence. In this review, we discuss the short- and long-term effects of periadolescent stress exposure on the structure and function of the brain. More specifically, we examine how stress at prepubertal and early adolescent stages of development affects the morphological plasticity of limbic and cortical brain regions, as well as the enduring effects of adolescent stress exposure on these brain regions in adulthood. We suggest that, due to a number of converging factors during this period of maturation, the adolescent brain may be particularly sensitive to stress-induced neurobehavioral dysfunctions with important consequences on an individual's immediate and long-term health and well-being.

Neural systems underlying motivated behavior in adolescence: implications for preventive medicine

OBJECTIVE

Although a time of increased independence and autonomy, adolescence is also a time of vulnerabilities, through increased risk-taking and the emergence of psychopathology. Neurodevelopmental changes during this period may provide a neurobiological basis for this normative rise in deleterious behaviors. Thus, the objective of this review was to identify neurodevelopmental processes underlying the emergence of risk-taking and psychopathology in adolescence, and discuss implications of these findings for prevention.

METHOD

This article reviews literature examining developmental and contextual factors influencing neural functioning in systems mediating threat, reward, and cognitive control. This literature is discussed from the perspective of the Triadic Neural Systems Model of motivated behavior.

RESULTS

Neuroimaging research suggests that neurodevelopmental and contextual factors both contribute to a shift in the functional equilibrium among the Triadic nodes. This equilibrium shift may contribute to negative outcomes of adolescent risk behavior. Most importantly, the balance of this equilibrium and its sensitivity to social and appetitive contexts may be exploited to facilitate prevention of deleterious outcomes.

CONCLUSION

Understanding developmental and contextual factors that influence functioning in motivational neural circuits can inform research on adolescent risk-taking, and may provide targets for novel preventions, for example through the use of incentives to reduce deleterious outcomes.

The relationship between puberty and social emotion processing

The social brain undergoes developmental change during adolescence, and pubertal hormones are hypothesized to contribute to this development. We used fMRI to explore how pubertal indicators (salivary concentrations of testosterone, oestradiol and DHEA; pubertal stage; menarcheal status) relate to brain activity during a social emotion task. Forty-two females aged 11.1 to 13.7 years underwent fMRI scanning while reading scenarios pertaining either to social emotions, which require the representation of another person’s mental states, or to basic emotions, which do not. Pubertal stage and menarcheal status were used to assign girls to early or late puberty groups. Across the entire sample, the contrast between social versus basic emotion resulted in activity within the social brain network, including dorsomedial prefrontal cortex (DMPFC), the posterior superior temporal sulcus, and the anterior temporal cortex (ATC) in both hemispheres. Increased hormone levels (independent of age) were associated with higher left ATC activity during social emotion processing. More advanced age (independent of hormone levels) was associated with lower DMPFC activity during social emotion processing. Our results suggest functionally dissociable effects of pubertal hormones and age on the adolescent social brain.

Behavioral risk elicits selective activation of the executive system in adolescents: clinical implications

We investigated adolescent brain processing of decisions under conditions of varying risk, reward, and uncertainty. Adolescents (n = 31) preformed a Decision-Reward Uncertainty task that separates decision uncertainty into behavioral and reward risk, while they were scanned using functional magnetic resonance imaging. Behavioral risk trials involved uncertainty about which action to perform to earn a fixed monetary reward. In contrast, during reward risk the decision that might lead to a reward was known, but the likelihood of earning a reward was probabilistically determined. Behavioral risk trials evoked greater activation than the reward risk and no risk conditions in the anterior cingulate, medial frontal gyrus, bilateral frontal poles, bilateral inferior parietal lobe, precuneus, bilateral superior-middle frontal gyrus, inferior frontal gyrus, and insula. Our results were similar to those of young adults using the same task (Huettel, 2006) except that adolescents did not show significant activation in the posterior supramarginal gyrus during behavioral risk. During the behavioral risk condition regardless of reward outcome, overall mean frontal pole activity showed a positive correlation with age during the behavioral and reward risk conditions suggesting a developmental difference of this region of interest. Additionally, reward response to the Decision-Reward Uncertainty task in adolescents was similar to that seen in young adults (Huettel, 2006). Our data did not show a correlation between age and mean ventral striatum activity during the three conditions. While our results came from a healthy high functioning non-maltreated sample of adolescents, this method can be used to address types of risks and reward processing in children and adolescents with predisposing vulnerabilities and add to the paucity of imaging studies of risk and reward processing during adolescence.

Pubertal development of the understanding of social emotions: Implications for education

Recent developmental cognitive neuroscience research has supported the notion that puberty and adolescence are periods of profound socio-emotional development. The current study was designed to investigate whether the onset of puberty marks an increase in the awareness of complex, or "mixed," emotions. Eighty-three female participants (aged 9-16 years) were divided into three groups according to a self-report measure of puberty stage (early-, mid- and post-puberty). Participants were presented with emotional scenarios, and used four linear scales to rate their emotional response to each scenario. Scenarios were designed to evoke social emotions (embarrassment or guilt) or basic emotions (anger or fear), where social emotions are defined as those which require the representation of others' mental states. We measured the relative complexity or "mixedness" of emotional responses, that is, the degree to which participants reported feeling more than one emotion for a given scenario. We found that mixed emotion reporting increased between early- and post-puberty for social emotion scenarios, and showed no relationship with age, whereas there was no change in mixed emotion reporting for basic emotion scenarios across age or puberty groups. This suggests that the awareness of mixed emotions develops during the course of puberty, and that this development is specific to social emotions. Results are discussed in the context of brain development across puberty and adolescence, with speculation regarding the potential implications for education.

The influence of emotion on cognitive control: relevance for development and adolescent psychopathology

The last decade has witnessed an explosion of research into the neural mechanisms underlying emotion processing on the one hand, and cognitive control and executive function on the other hand. More recently, studies have begun to directly examine how concurrent emotion processing influences cognitive control performance but many questions remain currently unresolved. Interestingly, parallel to investigations in healthy adults, research in developmental cognitive neuroscience and developmental affective disorders has provided some intriguing findings that complement the adult literature. This review provides an overview of current research on cognitive control and emotion interactions. It integrates parallel lines of research in adulthood and development and will draw on several lines of evidence ranging from behavioral, neurophysiological, and neuroimaging work in healthy adults and extend these to work in pediatric development and patients with affective disorders. Particular emphasis is given to studies that provide information on the neurobiological underpinnings of emotional and cognitive control processes using functional magnetic resonance imaging. The findings are then summarized and discussed in relation to neurochemical processes and the dopamine hypothesis of prefrontal cortical function. Finally, open areas of research for future study are identified and discussed within the context of cognitive control emotion interactions.

The association between sleep disordered breathing, academic grades, and cognitive and behavioral functioning among overweight subjects during middle to late childhood

STUDY OBJECTIVES

(1) to determine the associations of sleep disordered breathing (SDB) with behavioral functioning, cognitive test scores, and school grades during middle- to late-childhood, an under-researched developmental period in the SDB literature, and (2) to clarify whether associations between SDB and school grades are mediated by deficits in cognitive or behavioral functioning.

DESIGN

cross-sectional correlative study.

SETTING

Office/hospital, plus reported functioning at home and at school.

PARTICIPANTS

163 overweight subjects aged 10-16.9 years were divided into 4 groups based upon their obstructive apnea+hypopnea index (AHI) during overnight polysomnography and parent report of snoring: Moderate-Severe OSA (AHI > 5, n = 42), Mild OSA (AHI = 1-5, n = 58), Snorers (AHI < 1 + snoring, n = 26), and No SDB (AHI < 1 and nonsnoring, n = 37).

MEASUREMENTS

inpatient overnight polysomnography, parent- and self-report of school grades and sleep, parent- and teacher-report of daytime behaviors, and office-based neuropsychological testing.

RESULTS

The 4 groups significantly differed in academic grades and parent- and teacher-reported behaviors, particularly inattention and learning problems. These findings remained significant after adjusting for subject sex, race, socioeconomic status, and school night sleep duration. Associations with SDB were confined to reports of behavioral difficulties in real-world situations, and did not extend to office-based neuropsychological tests. Findings from secondary analyses were consistent with, but could not definitively confirm, a causal model in which SDB affects school grades via its impact on behavioral functioning.

CONCLUSIONS

SDB during middle- to late-childhood is related to important aspects of behavioral functioning, especially inattention and learning difficulties, that may result in significant functional impairment at school.

Heritability of delay discounting in adolescence: a longitudinal twin study

Delay discounting (DD) refers to the preference for smaller immediate rewards over larger but delayed rewards, and is considered to be a distinct component of a broader "impulsivity" construct. Although greater propensity for discounting the value of delayed gratification has been associated with a range of problem behaviors and substance abuse, particularly in adolescents, the origins of individual differences in DD remain unclear. We examined genetic and environmental influences on a real-life behavioral measure of DD using a longitudinal twin design. Adolescent participants were asked to choose between a smaller ($7) reward available immediately and a larger ($10) reward to be received in 7 days. Biometrical genetic analysis using linear structural equation modeling showed significant heritability of DD at ages 12 and 14 (30 and 51%, respectively) and suggested that the same genetic factors influenced the trait at both ages. DD was significantly associated with symptoms of conduct disorder, attention deficit hyperactivity disorder, substance use, and with higher novelty seeking and poor self-regulation. This study provides the first evidence for heritability of DD in humans and suggests that DD can be a promising endophenotype for genetic studies of addiction and externalizing disorders.

The etiology of diverse receptive language skills at 12 years

PURPOSE

In the 2nd decade of life, language skills expand in both quantitative and qualitative ways. The etiology of these new skills and the relationships among them have been little explored.

METHOD

Taking advantage of widespread access to inexpensive and fast Internet connections in the United Kingdom, we administered four Web-based measures of receptive language development--Vocabulary, Listening Grammar, Figurative Language, and Making Inferences--to a sample of 12-year-old twin pairs (N=4,892) participating in the Twins Early Development Study (TEDS; Oliver & Plomin, 2007).

RESULTS

The 4 measures showed moderate phenotypic intercorrelation. All 4 showed moderate genetic influence (a2 between .25 and .36) and low shared environmental influence (c2 between .13 and .19). The median genetic correlation among the 4 measures was .87, indicating strong genetic overlap among them. A latent factor score for Language, based on the common variance among the measures, showed substantial genetic influence (a2=.59) and moderate shared environmental influence (c2=.28). A small but significant sex difference favored females on the Listening Grammar and Making Inferences tests, but there was no evidence for sex differences in the etiology of any of the measures.

CONCLUSION

Despite the emergence of new skills at this developmental period, from the etiological perspective, language skills remain relatively undifferentiated at an etiological level.

Early-life stress is associated with impairment in cognitive control in adolescence: an fMRI study

Early-life stress (ES) has been associated with diverse forms of psychopathology. Some investigators suggest that these associations reflect the effects of stress on the neural circuits that support cognitive control. However, very few prior studies have examined the associations between ES, cognitive control, and underlying neural architecture. The present study compares adolescents with a documented history of ES to typical adolescents on a cognitive control task using functional magnetic resonance imaging (fMRI). Twelve ES adolescents who were adopted because of early caregiver deprivation (9 females, age=13 years+/-2.58) and 21 healthy control adolescents without a history of ES (10 females, age=13 years+/-1.96) who resided with their biological parents performed the change task (Nelson, Vinton et al., 2007)--a variant of the stop task--during fMRI. Behaviourally, ES adolescents took longer to switch from a prepotent response ("go") to an alternative response ("change") than control adolescents. During correct "change" responses vs. correct "go" responses, this behavioural group difference was accompanied by higher activation in ES subjects than controls. These differences were noted in regions involved in primary sensorimotor processes (pre- and postcentral gyri), conflict monitoring (dorsal anterior cingulate gyrus), inhibitory and response control (inferior prefrontal cortex and striatum), and somatic representations (posterior insula). Furthermore, correct "change" responses vs. incorrect "change" responses recruited the inferior prefrontal cortex (BA 44/46) more strongly in ES subjects than controls. These data suggest impaired cognitive control in youth who experienced ES.

Invited commentary: understanding brain mechanisms of pain processing in adolescents' non-suicidal self-injury

Whereas non-suicidal self injury (NSSI) is reported in 13-23% of adolescents and is an increasingly studied topic, there has been little investigation into the pathophysiology behind self-injury. This commentary examines recent research into pain and emotional distress to discuss implications for the manner we should understand, research, and treat NSSI in the future. Research indicates that adolescents may be particularly vulnerable to NSSI behaviors due to neurodevelopmental changes in the processing of distress and pain. Additionally, emotional distress and physical pain neural pathways may have been altered in these individuals, leading to the development of NSSI behaviors during adolescence when changes in ongoing brain development may lead to further emotional dysregulation and poor impulse control. Further studies that directly characterize the relationship between emotional distress and physical pain in adolescence, as well as the neural differences between self-injurers and non-self-injurers, are needed.

The emergence of gonadal hormone influences on dopaminergic function during puberty

Adolescence is the developmental epoch during which children become adults-intellectually, physically, hormonally and socially. Brain development in critical areas is ongoing. Adolescents are risk-taking and novelty-seeking and they weigh positive experiences more heavily and negative experiences less than adults. This inherent behavioral bias can lead to risky behaviors like drug taking. Most drug addictions start during adolescence and early drug-taking is associated with an increased rate of drug abuse and dependence. The hormonal changes of puberty contribute to physical, emotional, intellectual and social changes during adolescence. These hormonal events do not just cause maturation of reproductive function and the emergence of secondary sex characteristics. They contribute to the appearance of sex differences in non-reproductive behaviors as well. Sex differences in drug use behaviors are among the latter. The male predominance in overall drug use appears by the end of adolescence, while girls develop the rapid progression from first use to dependence (telescoping) that represent a female-biased vulnerability. Sex differences in many behaviors including drug use have been attributed to social and cultural factors. A narrowing gap in drug use between adolescent boys and girls supports this thesis. However, some sex differences in addiction vulnerability reflect biologic differences in brain circuits involved in addiction. The purpose of this review is to summarize the contribution of sex differences in the function of ascending dopamine systems that are critical to reinforcement, to briefly summarize the behavioral, neurochemical and anatomical changes in brain dopaminergic functions related to addiction that occur during adolescence and to present new findings about the emergence of sex differences in dopaminergic function during adolescence.

Adolescents' heightened risk-seeking in a probabilistic gambling task

This study investigated adolescent males’ decision-making under risk, and the emotional response to decision outcomes, using a probabilistic gambling task designed to evoke counterfactually mediated emotions (relief and regret). Participants were 20 adolescents (aged 9–11), 26 young adolescents (aged 12–15), 20 mid-adolescents (aged 15–18) and 17 adults (aged 25–35). All were male. The ability to maximize expected value improved with age. However, there was an inverted U-shaped developmental pattern for risk-seeking. The age at which risk-taking was highest was 14.38 years. Although emotion ratings overall did not differ across age, there was an increase between childhood and young adolescence in the strength of counterfactually mediated emotions (relief and regret) reported after receiving feedback about the gamble outcome. We suggest that continuing development of the emotional response to outcomes may be a factor contributing to adolescents’ risky behaviour.

Adolescent development of the reward system

Adolescence is a developmental period characterized by increased reward-seeking behavior. Investigators have used functional magnetic resonance imaging (fMRI) in conjunction with reward paradigms to test two opposing hypotheses about adolescent developmental changes in the striatum, a region implicated in reward processing. One hypothesis posits that the striatum is relatively hypo-responsive to rewards during adolescence, such that heightened reward-seeking behavior is necessary to achieve the same activation as adults. Another view suggests that during adolescence the striatal reward system is hyper-responsive, which subsequently results in greater reward-seeking. While evidence for both hypotheses has been reported, the field has generally converged on this latter hypothesis based on compelling evidence. In this review, I describe the evidence to support this notion, speculate on the disparate fMRI findings and conclude with future areas of inquiry to this fascinating question.

Adolescent development of the reward system

Adolescence is a developmental period characterized by increased reward-seeking behavior. Investigators have used functional magnetic resonance imaging (fMRI) in conjunction with reward paradigms to test two opposing hypotheses about adolescent developmental changes in the striatum, a region implicated in reward processing. One hypothesis posits that the striatum is relatively hypo-responsive to rewards during adolescence, such that heightened reward-seeking behavior is necessary to achieve the same activation as adults. Another view suggests that during adolescence the striatal reward system is hyper-responsive, which subsequently results in greater reward-seeking. While evidence for both hypotheses has been reported, the field has generally converged on this latter hypothesis based on compelling evidence. In this review, I describe the evidence to support this notion, speculate on the disparate fMRI findings and conclude with future areas of inquiry to this fascinating question.

Invited commentary: understanding brain mechanisms of pain processing in adolescents' non-suicidal self-injury

Whereas non-suicidal self injury (NSSI) is reported in 13-23% of adolescents and is an increasingly studied topic, there has been little investigation into the pathophysiology behind self-injury. This commentary examines recent research into pain and emotional distress to discuss implications for the manner we should understand, research, and treat NSSI in the future. Research indicates that adolescents may be particularly vulnerable to NSSI behaviors due to neurodevelopmental changes in the processing of distress and pain. Additionally, emotional distress and physical pain neural pathways may have been altered in these individuals, leading to the development of NSSI behaviors during adolescence when changes in ongoing brain development may lead to further emotional dysregulation and poor impulse control. Further studies that directly characterize the relationship between emotional distress and physical pain in adolescence, as well as the neural differences between self-injurers and non-self-injurers, are needed.

Learning abilities and disabilities: generalist genes in early adolescence

INTRODUCTION

The new view of cognitive neuropsychology that considers not just case studies of rare severe disorders but also common disorders, as well as normal variation and quantitative traits, is more amenable to recent advances in molecular genetics, such as genome-wide association studies, and advances in quantitative genetics, such as multivariate genetic analysis. A surprising finding emerging from multivariate quantitative genetic studies across diverse learning abilities is that most genetic influences are shared: they are "generalist", rather than "specialist".

METHODS

We exploited widespread access to inexpensive and fast Internet connections in the United Kingdom to assess over 5000 pairs of 12-year-old twins from the Twins Early Development Study (TEDS) on four distinct batteries: reading, mathematics, general cognitive ability (g) and, for the first time, language.

RESULTS

Genetic correlations remain high among all of the measured abilities, with language as highly correlated genetically with g as reading and mathematics.

CONCLUSIONS

Despite developmental upheaval, generalist genes remain important into early adolescence, suggesting optimal strategies for molecular genetic studies seeking to identify the genes of small effect that influence learning abilities and disabilities.

Why do many psychiatric disorders emerge during adolescence?

The peak age of onset for many psychiatric disorders is adolescence, a time of remarkable physical and behavioural changes. The processes in the brain that underlie these behavioural changes have been the subject of recent investigations. What do we know about the maturation of the human brain during adolescence? Do structural changes in the cerebral cortex reflect synaptic pruning? Are increases in white-matter volume driven by myelination? Is the adolescent brain more or less sensitive to reward? Finding answers to these questions might enable us to further our understanding of mental health during adolescence.