Different developmental trajectories for anticipation and receipt of reward during adolescence

The Effect of Efavirenz on Reward Processing in Asymptomatic People Living with HIV: A Randomized Controlled Trial

Functional magnetic resonance imaging (fMRI) studies have demonstrated that HIV-infection affects the fronto-striatal network. It has not been examined what impact efavirenz (EFV), an antiretroviral drug notorious for its neurocognitive effects, has on the reward system: a key subcomponent involved in depressive and apathy symptoms. Therefore, this study aims to investigate the effect of EFV on reward processing using a monetary incentive delay (MID) task. In this multicenter randomized controlled trial, asymptomatic adult participants stable on emtricitabine/tenofovirdisoproxil fumarate (FTC/TDF)/EFV were randomly assigned in a 2:1 ratio to switch to FTC/TDF/rilpivirine (RPV) (n = 30) or continue taking FTC/TDF/EFV (n = 13). At baseline and 12 weeks after therapy switch, both groups performed an MID task. Behavior and functional brain activity related to reward anticipation and reward outcome were assessed with blood-oxygen-level-dependent fMRI. Both groups were matched for age, education level, and time since HIV diagnosis and on EFV. At the behavioral level, both groups had faster response times and better response accuracy during rewarding versus nonrewarding trials, with no improvement resulting from switching FTC/TDF/EFV to FTC/TDF/RPV. No significant change in activation related to reward anticipation in the ventral striatum was found after switching therapy. Both groups had significantly higher activation levels over time, consistent with a potential learning effect. Similar activity related to reward outcome in the orbitofrontal cortex was found. Discontinuing FTC/TDF/EFV was not found to improve activity related to reward anticipation in asymptomatic people living with HIV, with similar cortical functioning during reward outcome processing. It is therefore likely that EFV does not affect motivational control. Further research is needed to determine whether EFV affects motivational control in HIV populations with different characteristics.

The effect of choice on memory across development

Numerous studies have demonstrated the role of making choices as an internal motivator to improve performance, and recent studies in the domain of memory have focused on adults. To chart the developmental trend of the choice effect on memory, we conducted a series of seven experiments involving children, adolescents, and young adults. Participants (N = 512) aged 5 to 26 years performed a choice encoding task that manipulated the opportunities to choose and then took a memory test. Using different types of experimental materials and corroborated by a mini meta-analysis, we found that the choice effect on memory was significant in childhood and early adolescence but not significant in late adolescence and early adulthood. The developmental changes were statistically significant, particularly evident during the transition from early to late adolescence. These findings suggest that the internal value of choice decreases across development and contributes to our understanding of developmental differences in the role of choice in memory.

Developmental differences in striatal recruitment by reward prospects as a function of attentional demand

Adolescent risk-taking has been attributed to earlier-developing motivational neurocircuitry that is poorly controlled by immature executive-control neurocircuitry. Functional magnetic resonance imaging findings of increased ventral striatum (VS) recruitment by reward prospects in adolescents compared to adults support this theory. Other studies found blunted VS recruitment by reward-predictive cues in adolescents compared to adults. Task features may explain this discrepancy but have never been systematically explored. Adolescents and adults performed a novel reward task that holds constant the expected value of all rewards but varies whether rewards are dependent on vigilance-intensive responding versus making a lucky choice during a relaxed response window. We examined group by sub-task contrast differences in activation of VS and more motoric regions of striatum in response to anticipatory cues. Reward anticipation in both task conditions activated portions of striatum in both groups. In voxel-wise comparison, adults showed greater anticipatory recruitment of VS in trials involving choice during a relaxed time window, not in the more vigilance-demanding trials as hypothesized. In accord with our hypotheses, however, adults showed greater activation in dorsal striatum and putamen volumes of interest during reward anticipation under vigilance-demanding conditions. Following trial outcome notifications, adolescents showed greater activation of the VS during reward notification but lower activation during loss notification. These data extend findings of cross-sectional age-group differences in incentive-anticipatory recruitment of striatum, by demonstrating in adults relatively greater recruitment of motor effector regions of striatum by attentional and motor demands.

Neural Reward Anticipation Moderates Longitudinal Relation between Parents' Familism Values and Latinx American Youth's School Disengagement

Parents' familism values predict a variety of Latinx American youth's academic adjustment. However, it is unclear how cultural values such as familism interact with youth's brain development, which is sensitive to sociocultural input, to shape their academic adjustment. Using a sample of 1916 Latinx American youth (mean age = 9.90 years, SD = .63 years; 50% girls) and their primary caregivers (mean age = 38.43 years, SD = 6.81 years; 90% mothers) from the Adolescent Brain Cognitive Development Study, this study examined the longitudinal relation between parents' familism values and youth's school disengagement, as well as the moderating role of youth's neural sensitivity to personal reward. Parents' familism values predicted youth's decreased school disengagement 1 year later, adjusting for their baseline school disengagement and demographic covariates. Notably, this association was more salient among youth who showed lower (vs. higher) neural activation in the ventral striatum and the lateral OFC during the anticipation of a personal reward. These findings underscore the protective role of familism for Latinx American youth, highlighting the necessity of developing culturally informed interventions that take into consideration a youth's brain development.

The role of neural reward sensitivity in the longitudinal relations between parents' familism values and Latinx American youth's prosocial behaviors

Past research suggests that parents' familism values play a positive role in Latinx American youth's prosocial tendencies. However, little is known about how individual differences in youth's neural development may contribute to this developmental process. Therefore, using two-wave longitudinal data of 1916 early adolescents (mean age = 9.90 years; 50% girls) and their parents (mean age = 38.43 years; 90% mothers) from the Adolescent Brain Cognitive Development study, this pre-registered study took a biopsychosocial approach to examine the moderating role of youth's neural reward sensitivity in the link between parents' familism values and youth's prosocial behaviors. Results showed that parents' familism values were associated with increased prosocial behaviors among youth two years later, controlling for baseline prosocial behaviors and demographic covariates. Notably, parents' familism values played a larger role in promoting youth's prosocial behaviors among youth who showed lower ventral striatum activation during reward anticipation. Moreover, such association between parents' familism values and youth's later prosocial behaviors was stronger among youth who showed lower levels of prosocial behaviors initially. Taken together, the findings highlight individual differences in neurobiological development and baseline prosocial behaviors as markers of sensitivity to cultural environments with regard to Latinx American youth's prosocial development.

Early life stress moderates the relation between systemic inflammation and neural activation to reward in adolescents both cross-sectionally and longitudinally

Elevated levels of systemic inflammation are associated with altered reward-related brain function in ventral striatal areas of the brain like the nucleus accumbens (NAcc). In adolescents, cross-sectional research indicates that exposure to early life stress (ELS) can moderate the relation between inflammation and neural activation, which may contribute to atypical reward function; however, no studies have tested whether this moderation by ELS of neuroimmune associations persists over time. Here, we conducted a cross-sectional analysis and the first exploratory longitudinal analysis testing whether cumulative severity of ELS moderates the association of systemic inflammation with reward-related processing in the NAcc in adolescents (n = 104; 58F/46M; M[SD] age = 16.00[1.45] years; range = 13.07-19.86 years). For the cross-sectional analysis, we modeled a statistical interaction between ELS and levels of C-reactive protein (CRP) predicting NAcc activation during the anticipation and outcome phases of a monetary reward task. We found that higher CRP was associated with blunted NAcc activation during the outcome of reward in youth who experienced higher levels of ELS (β = -0.31; p = 0.006). For the longitudinal analysis, we modeled an interaction between ELS and change in CRP predicting change in NAcc activation across 2 years. This analysis similarly showed that increasing CRP over time was associated with decreasing NAcc during reward outcomes in youth who experienced higher levels of ELS (β = -0.47; p = 0.022). Both findings support contemporary theoretical frameworks involving associations among inflammation, reward-related brain function, and ELS exposure, and suggest that experiencing ELS can have significant and enduring effects on neuroimmune function and adolescent neurodevelopment.

The longitudinal role of family conflict and neural reward sensitivity in youth's internalizing symptoms

Adolescence is often associated with an increase in psychopathology. Although previous studies have examined how family environments and neural reward sensitivity separately play a role in youth's emotional development, it remains unknown how they interact with each other in predicting youth's internalizing symptoms. Therefore, the current research took a biopsychosocial approach to examine this question using two-wave longitudinal data of 9353 preadolescents (mean age = 9.93 years at T1; 51% boys) from the Adolescent Brain Cognitive Development study. Using mixed-effects models, results showed that higher family conflict predicted youth's increased internalizing symptoms 1 year later, whereas greater ventral striatum (VS) activity during reward receipt predicted reduced internalizing symptoms over time. Importantly, there was an interaction effect between family conflict and VS activity. For youth who showed greater VS activation during reward receipt, high family conflict was more likely to predict increased internalizing symptoms. In contrast, youth with low VS activation during reward receipt showed high levels of internalizing symptoms regardless of family conflict. The findings suggest that youth's neural reward sensitivity is a marker of susceptibility to adverse family environments and highlight the importance of cultivating supportive family environments where youth experience less general conflict within the family.

Positive risk taking and neural sensitivity to risky decision making in adolescence

This study examines associations between adolescents' positive risk taking and neural activation during risky decision-making. Participants included 144 adolescents ages 13-16 years (Mage = 14.23; SDage = 0.7) from diverse racial and ethnic groups. Participants self-reported their engagement in positive and negative risk taking. Additionally, participants played the Cups task during fMRI, where they chose between a safe choice (guaranteed earning of 15 cents) and a risky choice (varying probabilities of earning more than 15 cents). Using a risk-return framework, we examined adolescents' sensitivity to both risks (safe versus risky) and returns (expected value, or potential reward as a function of its probability of occurring) at the behavioral and neural levels. All participants took more risks when the expected value of the choice was high. However, high positive risk taking was uniquely associated with dampened dmPFC tracking of expected value. Together, results show that adolescents' positive risk taking is associated with neural activity during risky decision-making. Findings are among the first to identify brain-behavior correlations associated with positive risk taking during adolescence.

Childhood trauma exposure and reward processing in healthy adults: A functional neuroimaging study

The association between childhood trauma exposure and risk of developing psychopathology may in part be mediated by the effects of chronic stress on dopaminergic neurotransmission. However, little is known about the differential effects of distinct trauma types on reward processing, particularly in adults without concurrent medical or psychiatric disorders. We examined the association of childhood trauma exposure, including the differential effects of abuse and neglect, with reward processing in healthy adults (n = 114). Functional magnetic resonance imaging during a monetary incentive delay task was used to assess neural activity in the ventral striatum and orbitofrontal cortex in relation to reward anticipation and reward outcome, respectively. Exposure to childhood trauma, including abuse and neglect, was assessed using the Childhood Trauma Questionnaire-Short Form. We found a significant effect for abuse on ventral striatal activation during reward anticipation, adjusting for age, sex, scanner site, educational level, and household monthly income. There were no effects for abuse or neglect, independently or combined, on orbitofrontal cortex activation during reward outcome. Our findings suggest differential effects of childhood abuse on ventral striatum activation during reward anticipation in healthy adults.

The influence of reward anticipation on conflict control in children and adolescents: Evidences from hierarchical drift-diffusion model and event-related potentials

Reward is deemed a performance reinforcer. The current study investigated how social and monetary reward anticipation affected cognitive control in 39 children, 40 adolescents, and 40 adults. We found that cognitive control performance improved with age in a Simon task, and the reaction time (RT) was modulated by the reward magnitude. The conflict monitoring process (target N2 amplitudes) of adolescents and the attentional control processes (target P3 amplitudes) of adolescents and adults could be adjusted by reward magnitude, suggesting that adolescents were more sensitive to rewards compared to children. Reward magnitudes influenced the neural process of attentional control with larger P3 in congruent trails than that in incongruent trials only in low reward condition. The result of hierarchical drift-diffusion model indicated that children had slower drift rates, higher decision threshold, and longer non-decision time than adolescents and adults. Adolescents had faster drift rates in monetary task than in social task under the high reward condition, and they had faster drift rates under high reward condition than no reward condition only in the monetary task. The correlation analysis further showed that adults' non-decision time and decision threshold correlated with conflict monitoring process (N2 responses) and attentional control process on conflicts (P3 responses). Adolescents' drift rates associated with neural process of attentional control. The current study reveals that reward magnitude and reward type can modulate cognitive control process, especially in adolescents.

Impact of restrictive COVID-19 measures on daily momentary affect in an epidemiological youth sample in Hong Kong: An experience sampling study

Restrictive COVID-19 measures can have significant mental health impacts, particularly on young people. How such measures may influence day-to-day momentary affect, nonetheless, remains to be explored. Experience sampling data were collected from 165 young people (aged 15-24) as part of a larger epidemiological youth mental health study in Hong Kong. We examined the impact of one of the most stringent COVID-19 measures - dine-in restrictions - on momentary positive and negative affect and current contexts and activities of these young people. The effects of a milder form of COVID-19 measure - school suspension - were separately examined. Multilevel analysis revealed that those in the dine-in ban group, compared to dining-as-usual, showed significantly reduced momentary positive affect (β = -0.17, SE = 0.06, p = 0.003). Its effect remained significant even when accounting for baseline depressive and anxiety symptoms and socioeconomic status (β = -0.15, SE = 0.05, p = 0.008). The effect of dine-in ban on reduced momentary positive affect was found specifically when participants were in indoor locations (e.g., home, office), alone, and engaged in passive leisure activities. This pattern was not observed when participants were at school or at other outdoor locations, with friends, or engaged in active leisure activities. No significant effect of school suspension on momentary affect was observed. More severe COVID-19 measures, such as dine-in ban, can have significant impacts on the momentary positive affect of young people. Certain contexts and activities may offer protection against the consequences of COVID-19 measures. The current findings may help to inform future designs of mental health interventions and public health policies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12144-022-03183-y.

As they wait: Anticipatory neural response to evaluative peer feedback varies by pubertal status and social anxiety

Adolescence is a developmental period characterized by substantial biological, neural, behavioral, and social changes. Learning to navigate the complex social world requires adaptive skills. Although anticipation of social situations can serve an adaptive function, providing opportunity to adjust behavior, socially anxious individuals may engage in maladaptive anticipatory processing. Importantly, elevated social anxiety often coincides with adolescence. This study investigated cortical electroencephalogram (EEG) responses during anticipation of evaluative feedback in 106 healthy adolescents aged 12–17 years. We examined differences in anticipatory event-related potentials (i.e., stimulus preceding negativity [SPN]) in relation to social anxiety levels and pubertal maturation. As expected, the right frontal SPN was more negative during feedback anticipation, particularly for adolescents with higher social anxiety and adolescents who were at a more advanced pubertal stage. Effects for the left posterior SPN were the opposite of those for the right frontal SPN consistent with a dipole. Anticipatory reactivity in adolescence was related to social anxiety symptom severity, especially in females, and pubertal maturation in a social evaluative situation. This study provides evidence for the development of social anticipatory processes in adolescence and potential mechanisms underlying maladaptive anticipation in social anxiety.

Neural reward circuit dysfunction as a risk factor for bipolar spectrum disorders and substance use disorders: A review and integration

Bipolar spectrum disorders (BSDs) and substance use disorders (SUDs) are associated with neural reward dysfunction. However, it is unclear what pattern of neural reward function underlies pre-existing vulnerability to BSDs and SUDs, or whether neural reward function explains their high co-occurrence. The current paper provides an overview of the separate literatures on neural reward sensitivity in BSDs and SUDs. We provide a systematic review of 35 studies relevant to identifying neural reward function vulnerability to BSDs and SUDs. These studies include those examining neural reward processing on a monetary reward task with prospective designs predicting initial onset of SUDs, familial risk studies that examine unaffected offspring or first-degree relatives of family members with BSDs or SUDs, and studies that examine individuals with BSDs or SUDs who are not currently in an episode of the disorder. Findings from the review highlight that aberrant responding and connectivity across neural regions associated with reward and cognitive control confers risk for the development of BSDs and SUDs. Discussion focuses on limitations of the extant literature. We conclude with an integration and theoretical model for understanding how aberrant neural reward responding may constitute a vulnerability to the development of both BSDs and SUDs.

Brain reactivity to humorous films is affected by insomnia

STUDY OBJECTIVES

Emotional reactivity to negative stimuli has been investigated in insomnia, but little is known about emotional reactivity to positive stimuli and its neural representation.

METHODS

We used 3T fMRI to determine neural reactivity during the presentation of standardized short, 10-40-s, humorous films in insomnia patients (n=20, 18 females, aged 27.7 +/- 8.6 years) and age-matched individuals without insomnia (n=20, 19 females, aged 26.7 +/- 7.0 years), and assessed humour ratings through a visual analogue scale (VAS). Seed-based functional connectivity was analysed for left and right amygdala networks: group-level mixed-effects analysis (FLAME; FSL) was used to compare amygdala connectivity maps between groups.

RESULTS

fMRI seed-based analysis of the amygdala revealed stronger neural reactivity in insomnia patients than in controls in several brain network clusters within the reward brain network, without humour rating differences between groups (p = 0.6). For left amygdala connectivity, cluster maxima were in the left caudate (Z=3.88), left putamen (Z=3.79) and left anterior cingulate gyrus (Z=4.11), while for right amygdala connectivity, cluster maxima were in the left caudate (Z=4.05), right insula (Z=3.83) and left anterior cingulate gyrus (Z=4.29). Cluster maxima of the right amygdala network were correlated with hyperarousal scores in insomnia patients only.

CONCLUSIONS

Presentation of humorous films leads to increased brain activity in the neural reward network for insomnia patients compared to controls, related to hyperarousal features in insomnia patients, in the absence of humor rating group differences. These novel findings may benefit insomnia treatment interventions.

The ups and downs of relating nondrug reward activation to substance use risk in adolescents

Purpose of review

A wealth of epidemiological and cohort research, together with a healthy dose of anecdote, has characterized late-adolescence and emerging adulthood as a time of increased substance use and other risky behaviors. This review will address whether differences between adolescents or between adolescents and other age groups in dopaminergic mesolimbic recruitment by (non-drug) rewards inferred from functional magnetic resonance imaging (fMRI) could partially explain morbidity and mortality from risky-behavior-related causes in adolescents.

Recent findings

Recent findings do not suggest a definitive directionality with regard to whether increased vs decreased mesolimbic responsiveness to nondrug rewards correlates with real-world risk-taking. Inconsistent relationships between reward-activation and real-world risky behavior in these reports reflect in part methodological differences as well as conceptual differences between populations in terms of whether tepid mesolimbic recruitment by rewards is a marker of psychiatric health.

Summary

There are several potential reasons why the directionality of relationships between reward-elicited brain activation and substance use risk (specifically) might differ. These factors include differences between adolescents in histories/exposure of substance use, motivation for substance use, the component of the instrumental behavior being studied, and the cognitive demands of the incentive tasks. Systematic manipulation of these discrepant study factors might offer a way forward to clarify how motivational neurocircuit function relates to addiction risk in adolescents.

Neural processes of reward and punishment processing in childhood and adolescence: An event-related potential study on age differences

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Children and adolescents performed the Monetary Incentive Delay Task.

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We examined anticipatory and outcome ERPs of reward and punishment processing.

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SPN amplitudes for anticipating loss or no gain decreased with increasing age.

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Sensitivity to negative outcomes decreases from childhood to adolescence.

Reward and punishment processing are subject to substantial developmental changes during youth. However, little is known about the neurophysiological correlates that are associated with these developmental changes, particularly with regard to both anticipatory and outcome processing stages. Thus, the aim of this study was to address this research gap in a sample of typically developing children and adolescents.

Fifty-four children and adolescents (8–18 years) performed a Monetary Incentive Delay Task comprising a monetary reward and punishment condition. Using event-related brain potential recordings, the cue-P3 and the stimulus-preceding negativity (SPN) were analyzed during the anticipation phase, while the Reward Positivity and the feedback-P3 were analyzed during the outcome phase.

When anticipating monetary loss or no gain, SPN amplitude in the right hemisphere decreased with age. Moreover, exploratory analyses revealed a decrease in feedback-P3 amplitudes in response to monetary loss with increasing age. No other group differences were observed.

Age-related changes in the SPN and fP3 component suggest that sensitivity to negative outcomes decreases from childhood to late adolescence, supporting the notion that adolescence is associated with reduced harm-avoidance. Longitudinal research including young adults is needed to substantiate our findings and its clinical implications regarding disturbed developmental trajectories in psychiatric populations.

Cross-sectional exploration of brain functional connectivity in the triadic development model of adolescents

Adolescence represents a transitional stage with increased risk taking and mood dysregulation. These vulnerabilities are accountable by developmental dynamics in the triadic functional brain networks underlying reward seeking (REW), emotional avoidance (EMO), and cognitive regulation (COG). However, these triadic dynamics, though conceptually established, have yet been investigated directly. Capitalizing on public database of resting-state fMRI from 222 adolescents (8-18 years old, 89F133M), this study examined cross-sectional development profiles of functional connectivity (FC) by jointly considering bilateral seeds of the ventral striatum, amygdala, and dorsal lateral prefrontal cortex in probing the networks of REW, EMO, and COG, respectively. Positive and negative FCs were considered separately for clarification of synergetic and suppressive interactions. While the REW and EMO mostly exhibited quadratic FC changes across age, suggesting reduced reward sensitivity and risk avoidance, the COG exhibited both linear and quadratic FC changes, suggesting both protracted maturation of cognitive ability and lowered top-down regulation. Additional age × gender effects were identified in the precentral gyrus and superior medial prefrontal cortex, which may associate risky action and emotion dysregulation to boys and girls, respectively. These results provide network evidence in substantiating the "triadic model" and deepening existing insights into neurodevelopmental mechanisms associated with adolescent behavior.

Suppression of ovarian hormones in adolescent rats has no effect on anxiety-like behaviour or c-fos activation in the amygdala

In humans, sex differences in mood disorders emerge during adolescence, with prevalence rates being consistently higher in females than males. It has been hypothesised that exposure to endogenous ovarian hormones during adolescence enhances the susceptibility of females to mood disorders from this stage of life onwards. However, experimental evidence in favour of this hypothesis is lacking. In the present study, we examined the long-term effects of suppressing adolescent gonadal hormone levels in a group of female Lister-hooded rats via administration of a gonadotrophin-releasing hormone antagonist (Antide; administered on postnatal day [PND] 28 and 42) compared to control females and males (n = 14 per group). We predicted that, in adulthood, Antide-treated female rats would exhibit more male-like behaviour than control females in novel environments (elevated-plus maze, open field and light-dark box), in response to novel objects and novel social partners, and in an acoustic startle task. Progesterone and luteinising hormone assays (which were conducted on blood samples collected on PND 55/56 and 69/70) confirmed that the hypothalamic-pituitary-gonadal axis was temporarily suppressed by Antide treatment. In addition, Antide-treated females were found to exhibit a modest pubertal delay, as measured by vaginal opening, which was comparable in length to the pubertal delay that has been induced by adolescent exposure to alcohol or stress in previous studies of female rats. However, Antide-treated females did not substantially differ from control females on any of the behavioural tests, despite the evidence for predicted sex differences in some measures. Following the acoustic startle response task, all subjects were culled and perfused, and c-Fos staining was conducted in the medial and basolateral amygdala, with the results showing no significant differences in cell counts between the groups. These findings suggest that ovarian hormone exposure during adolescence does not have long-term effects on anxiety-related responses in female rats.

Towards an integrated account of the development of self-regulation from a neurocognitive perspective: A framework for current and future longitudinal multi-modal investigations

Self-regulation is the ability to monitor and modulate emotions, behaviour, and cognition in order to adapt to changing circumstances. Developing adequate self-regulation is associated with better social coping and higher educational achievement later in life; poor self-regulation has been linked to a variety of detrimental developmental outcomes. Here, we focus on the development of neurocognitive processes essential for self-regulation. We outline a conceptual framework emphasizing that this is inherently an integrated, dynamic process involving interactions between brain maturation, child characteristics (genetic makeup, temperament, and pre- and perinatal factors) and environmental factors (family characteristics, parents and siblings, peers, and broader societal influences including media development). We introduce the Consortium of Individual Development (CID), which combines a series of integrated large-scale, multi-modal, longitudinal studies to take essential steps towards the ultimate goal of understanding and supporting this process.

Neural processes during adolescent risky decision making are associated with conformity to peer influence

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Adolescents’ neural responses to risky decisions may modulate their conformity to different types of peer influence.

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Neural activity in the anterior cingulate cortex (ACC) predicted conformity to risky peers while driving.

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Connectivity between VS and risk processing regions (including insula and ACC) predicted safer driving under risky influence.

Adolescents demonstrate both heightened sensitivity to peer influence and increased risk-taking. The current study provides a novel test of how these two phenomena are related at behavioral and neural levels. Adolescent males (N = 83, 16–17 years) completed the Balloon Analogue Risk Task (BART) in an fMRI scanner. One week later, participants completed a driving task in which they drove alone and with a safety- or risk-promoting peer passenger. Results showed that neural responses during BART were associated with participants’ behavioral conformity to safe vs. risky peer influence while later driving. First, the extent that neural activation in the anterior cingulate cortex (ACC) scaled with decision stakes in BART was associated with conformity to risky peer influence. Additionally, stake-modulated functional connectivity between ventral striatum (VS) and risk processing regions (including ACC and insula) was associated with safer driving under risky peer influence (i.e. resistance to risky peer influence), suggesting that connectivity between VS and ACC as well as insula may serve a protective role under risky peer influence. Together, these results suggest that adolescents’ neural responses to risky decision making may modulate their behavioral conformity to different types of peer influence on risk taking.

Effect of alcohol use on the adolescent brain and behavior

Adolescence is a particularly vulnerable neurodevelopmental period marked by high rates of engagement with risky alcohol use. This review summarizes the cognitive and neural consequences following alcohol use during adolescence from longitudinal design studies in humans and animals. Findings from human adolescent studies suggest that binge drinking and heavy alcohol use is associated with poorer cognitive functioning on a broad range of neuropsychological assessments, including learning, memory, visuospatial functioning, psychomotor speed, attention, executive functioning, and impulsivity. Alcohol use during adolescence is associated with accelerated decreases in gray matter and attenuated increases in white matter volume, and aberrant neural activity during executive functioning, attentional control, and reward sensitivity tasks, when compared to non-drinking adolescents. Animal studies in rodents and non-human primates have replicated human findings, and suggest cognitive and neural consequences of adolescent alcohol use may persist into adulthood. Novel rodent studies demonstrate that adolescent alcohol use may increase reward responsiveness of the dopamine system to alcohol later in life, as well as disrupt adolescent neurogenesis, potentially through neuroinflammation, with long-lasting neural and behavioral effects into adulthood. Larger longitudinal human cognitive and neuroimaging studies with more diverse samples are currently underway which will improve understanding of the impact of polysubstance use, as well as the interactive effects of substance use, physical and mental health, and demographic factors on cognition and neurodevelopment.

Neural Dynamic Responses of Monetary and Social Reward Processes in Adolescents

Adolescence is an essential developmental period characterized by reward-related processes. The current study investigated the development of monetary and social reward processes in adolescents compared with that in children and adults; furthermore, it assessed whether adolescents had different levels of sensitivity to various types of rewards. Two adapted incentive delay tasks were employed for each participant, and event-related potentials (ERPs) were recorded. The behavioral results showed that both monetary and social rewards could motivate response speed, and participants were more accurate under the monetary reward condition than under the social reward condition. The behavioral performances of individuals increased with age. For the ERP data, the cue-P3, target-P2, target-P3 and feedback-related negativity (FRN) components were investigated to identify reward motivation, emotional arousal, attention allocation and feedback processing. Children and adolescents showed higher motivation (larger cue-P3) to rewards than adults. Adolescents showed larger emotional responses to rewards; that is, they had larger target-P2 amplitudes than adults and shorter target-P2 latencies than children. Children showed stronger emotional reactivity for monetary rewards than for social rewards. All age groups had stronger attentional control (larger target-P3) under the monetary reward condition than under the social reward condition. The present study sheds light on the neurodevelopment of reward processes in children, adolescents and adults and shows that various reward process stages demonstrate different age-related and reward-type-related characteristics.

Neural and neurocognitive markers of vulnerability to gambling disorder: a study of unaffected siblings

Psychological and neurobiological markers in individuals with gambling disorder (GD) could reflect transdiagnostic vulnerability to addiction or neuroadaptive consequences of long-term gambling. Using an endophenotypic approach to identify vulnerability markers, we tested the biological relatives of cases with GD. Male participants seeking treatment for GD (n = 20) were compared with a male control group (n = 18). Biological siblings of cases with GD (n = 17, unrelated to the current GD group) were compared with a separate control group (n = 19) that overlapped partially with the GD control group. Participants completed a comprehensive assessment of clinical scales, neurocognitive functioning, and fMRI of unexpected financial reward. The GD group displayed elevated levels of self-report impulsivity and delay discounting, and increased risk-taking on the Cambridge Gamble Task. We did not observe impaired motor impulsivity on the stop-signal task. Siblings of GD showed some overlapping effects; namely, elevated impulsivity (negative urgency) and increased risk-taking on the Cambridge Gamble Task. We did not observe any differences in the neural response to win outcomes, either in the GD or sibling analysis compared with their control group. Within the GD group, activity in the thalamus and caudate correlated negatively with gambling severity. Increased impulsivity and risk-taking in GD are present in biological relatives of cases with GD, suggesting these markers may represent pre-existing vulnerability to GD.

Using Developmental Science to Distinguish Adolescents and Adults Under the Law

A developmental scientific perspective on drawing legal age boundaries begins with the premise that the age at which the rights and responsibilities of adulthood are conferred to minors must align with the psychological capacities and skills necessary to exercise good judgment in specific contexts. This article examines three aspects of development relevant to this analysis: cognitive capabilities, especially those that support reasoned and deliberative decision making; psychosocial capacities, especially those that facilitate self-regulation under conditions of social or emotional arousal; and neurobiological maturation in brain regions and systems that undergird these cognitive and psychosocial skills. We conclude that the maturation of the capacity to reason and deliberate systematically precedes, by as much as five years, the maturation of the ability to exercise self-regulation, especially in socially and emotionally arousing contexts. Legal age boundaries should distinguish between two very different decision-making contexts: those that allow for unhurried, logical reflection and those that do not.

Reward anticipation in individuals with subclinical psychotic experiences: A functional MRI approach

Previous research in patients with psychotic disorder has shown widespread abnormalities in brain activation during reward anticipation. Research at the level of subclinical psychotic experiences in individuals unexposed to antipsychotic medication is limited with inconclusive results. Therefore, brain activation during reward anticipation was examined in a larger sample of individuals with subclinical psychotic experiences (PE). Participants in the PE-group were included based on CAPE scores. A sample of emerging adults aged 16-26 years (n = 47) with PE and healthy controls (HC) (n = 40) underwent fMRI scanning. The Monetary Incentive Delay task was conducted with cues related to win, loss or neutral conditions. fMRI nonparametric tests were used to examine the reward versus neutral cue contrast. A significant main effect of the large win (€3.00) > neutral contrast was found in both groups showing activation in many brain areas, including classic reward regions. Whole brain analysis on the group comparison regarding the large win > neutral contrast showed significantly decreased activation in the right insula, putamen and supramarginal gyrus in the PE-group compared to controls. There was no group difference in the hypothesized reward-related region. Decreased activation in the right insula, putamen and supramarginal gyrus during reward anticipation in individuals with PE may be consistent with altered processing of sensory information, related to decreased emotional valuing and motivational tendencies and/or altered motor-cognitive processes. The absence of group differences in striatal activation suggests that activation here is intact in the earliest stages of psychosis and may exhibit progressive deterioration in as the disease develops.

Peri-adolescent alcohol consumption increases sensitivity and dopaminergic response to nicotine during adulthood in female alcohol-preferring (P) rats: Alterations to α7 nicotinic acetylcholine receptor expression

Adolescent alcohol drinking has been linked to increased risk for drug abuse during adulthood. Nicotine microinjected directly into the posterior ventral tegmental area (pVTA) stimulates dopamine (DA) release in the nucleus accumbens (NAc) shell. The α7 nicotinic acetylcholine receptor (nAChR) is a potent regulator of dopaminergic activity in the pVTA. The current experiments examined the effects of peri-adolescent ethanol (EtOH) drinking on the ability of intra-pVTA nicotine to stimulate DA release during adulthood and alterations in α7 nAChR expression within the pVTA. Alcohol-preferring (P) female rats consumed EtOH and/or water during adolescence (post-natal day [PND] 30-60) or adulthood (PND 90-120). Thirty days following removal of EtOH, subjects received microinjections of 1 μM, 10 μM, or 50 μM nicotine into the pVTA concurrently with microdialysis for extracellular DA in the NAc shell. Brains were harvested from an additional cohort after PND 90 for quantification of α7 nAChR within the pVTA. The results indicated that only adolescent EtOH consumption produced a leftward and upward shift in the dose response curve for nicotine to stimulate DA release in the NAc shell. Investigation of α7 nAChR expression within the pVTA revealed a significant increase in animals that consumed EtOH during adolescence compared to naïve animals. The data suggests that peri-adolescent EtOH consumption produced cross-sensitization to the effects of nicotine during adulthood. The interaction between adolescent EtOH consumption and inflated adult risk for drug dependency could be predicated, at least in part, upon alterations in α7 nAChR expression within the mesolimbic reward pathway.

Brain Responses to Anticipation and Consumption of Beer with and without Alcohol

Beer is a popular alcoholic beverage worldwide. Nonalcoholic beer (NA-beer) is increasingly marketed. Brain responses to beer and NA-beer have not been compared. It could be that the flavor of beer constitutes a conditioned stimulus associated with alcohol reward. Therefore, we investigated whether oral exposure to NA-beer with or without alcohol elicits similar brain responses in reward-related areas in a context where regular alcoholic beer is expected. Healthy men (n = 21) who were regular beer drinkers were scanned using functional MRI. Participants were exposed to word cues signaling delivery of a 10-mL sip of chilled beer or carbonated water (control) and subsequent sips of NA-beer with or without alcohol or water (control). Beer alcohol content was not signaled. The beer cue elicited less activation than the control cue in the primary visual cortex, supplementary motor area (reward-related region) and bilateral inferior frontal gyrus/frontal operculum. During tasting, there were no significant differences between the 2 beers. Taste activation after swallowing was significantly greater for alcoholic than for NA-beer in the inferior frontal gyrus/anterior insula and dorsal prefrontal cortex (superior frontal gyrus). This appears to be due to sensory stimulation by ethanol rather than reward processing. In conclusion, we found no differences in acute brain reward upon consumption of NA-beer with and without alcohol, when presented in a context where regular alcoholic beer is expected. This suggests that in regular consumers, beer flavor rather than the presence of alcohol is the main driver of the consumption experience.

Let's chat: developmental neural bases of social motivation during real-time peer interaction

Humans are motivated to interact with each other, but the neural bases of social motivation have been predominantly examined in non-interactive contexts. Understanding real-world social motivation is of special importance during middle childhood (ages 8-12), a period when social skills improve, social networks grow, and social brain networks specialize. To assess interactive social motivation, the current study used a novel fMRI paradigm in which children believed they were chatting with a peer. The design targeted two phases of interaction: (1) Initiation, in which children engaged in a social bid via sharing a like or hobby, and (2) Reply, in which children received either an engaged ("Me too") or non-engaged ("I'm away") reply from the peer. On control trials, children were told that their answers were not shared and that they would receive either engaged ("Matched") or non-engaged ("Disconnected") replies from the computer. Results indicated that during Initiation and Reply, key components of reward circuitry (e.g., ventral striatum) were more active for the peer than the computer trials. In addition, during Reply, social cognitive regions were more activated by the peer, and this social cognitive specialization increased with age. Finally, the effect of engagement type on reward circuitry activation was larger for social than non-social trials, indicating developmental sensitivity to social contingency. These findings demonstrate that both reward and social cognitive brain systems support real-time social interaction in middle childhood. An interactive approach to understanding social reward has implications for clinical disorders, where social motivation is more affected in real-world contexts.

Neural Substrates of Counterfactual Emotions After Risky Decisions in Late Adolescents and Young Adults

Adolescents' neural substrates of emotional reactions to the consequences of risky decisions are poorly understood. In this functional magnetic resonance imaging study, 30 late adolescents and 30 young adults made risky and neutral decisions in social scenarios and received valenced outcomes. Negative outcomes in risky decisions eliciting regret, as compared with negative outcomes in neutral decisions eliciting disappointment, activated executive control (orbitofrontal cortex) and self-relevance regions (middle temporal gyrus [MTG], posterior cingulate cortex, and precuneus) for both age groups. Young adults showed more activation than adolescents in regret and disappointment as compared with relief and elation conditions in the avoidance (insula), action monitoring (inferior frontal gyrus, pre-SMA, and caudate), and social-cognition regions (superior temporal sulcus and MTG). These late socio-emotional developments may pave the way for more adaptive decision-making behavior in social contexts.

Effects of adolescent alcohol consumption on the brain and behaviour

Per occasion, alcohol consumption is higher in adolescents than in adults in both humans and laboratory animals, with changes in the adolescent brain probably contributing to this elevated drinking. This Review examines the contributors to and consequences of the use of alcohol in adolescents. Human adolescents with a history of alcohol use differ neurally and cognitively from other adolescents; some of these differences predate the commencement of alcohol consumption and serve as potential risk factors for later alcohol use, whereas others emerge from its use. The consequences of alcohol use in human adolescents include alterations in attention, verbal learning, visuospatial processing and memory, along with altered development of grey and white matter volumes and disrupted white matter integrity. The functional consequences of adolescent alcohol use emerging from studies of rodent models of adolescence include decreased cognitive flexibility, behavioural inefficiencies and elevations in anxiety, disinhibition, impulsivity and risk-taking. Rodent studies have also showed that adolescent alcohol use can impair neurogenesis, induce neuroinflammation and epigenetic alterations, and lead to the persistence of adolescent-like neurobehavioural phenotypes into adulthood. Although only a limited number of studies have examined comparable measures in humans and laboratory animals, the available data provide evidence for notable across-species similarities in the neural consequences of adolescent alcohol exposure, providing support for further translational efforts in this context.

Reward processing dysfunction in ventral striatum and orbitofrontal cortex in Parkinson's disease

BACKGROUND

Parkinson's disease is a growing concern as the longevity of the world's population steadily increases. Both ageing and Parkinson's disease have an impact on dopamine neurotransmission. It is therefore important to investigate their relative impact on the fronto-striatal reward system. There has been little investigation of reward processing in terms of anticipation and reward outcome in Parkinson's disease. Abnormal responses during reward processing have previously been demonstrated in whole-brain analysis of Parkinson's patients with mild lateralized disease, but the exact impact in regions specific to reward processing is still unknown.

OBJECTIVE

Here we aim to investigate the impact of Parkinson's disease on the orbitofrontal ventral striatal reward system in patients with moderate to severe clinical symptoms.

METHODS

We utilized a monetary incentive delay (MID) task in 17 Parkinson's patients who were compared to two control groups stratified by age. The MID paradigm reliably activates the ventral striatum during reward anticipation and the orbitofrontal cortex during reward outcome processing.

RESULTS

Relative to the two control groups, Parkinson's disease patients had abnormal task related activity during both reward anticipation in the ventral striatum and reward outcome in the orbitofrontal cortex. There were no effects of ageing.

CONCLUSION

These findings demonstrate abnormalities in anticipatory as well as reward outcome processing while treated primarily with levodopa. The orbitofrontal dysfunction during reward outcome processing may have specificity in Parkinson's disease, as it has been shown to be relatively unaffected by normal ageing.

Blunted ventral striatal responses to anticipated rewards foreshadow problematic drug use in novelty-seeking adolescents

Novelty-seeking tendencies in adolescents may promote innovation as well as problematic impulsive behaviour, including drug abuse. Previous research has not clarified whether neural hyper- or hypo-responsiveness to anticipated rewards promotes vulnerability in these individuals. Here we use a longitudinal design to track 144 novelty-seeking adolescents at age 14 and 16 to determine whether neural activity in response to anticipated rewards predicts problematic drug use. We find that diminished BOLD activity in mesolimbic (ventral striatal and midbrain) and prefrontal cortical (dorsolateral prefrontal cortex) regions during reward anticipation at age 14 predicts problematic drug use at age 16. Lower psychometric conscientiousness and steeper discounting of future rewards at age 14 also predicts problematic drug use at age 16, but the neural responses independently predict more variance than psychometric measures. Together, these findings suggest that diminished neural responses to anticipated rewards in novelty-seeking adolescents may increase vulnerability to future problematic drug use.

Some adolescents seek novelty, but it is unknown whether the brain circuits underlying this behaviour can be used to predict later, problematic behaviour. Here, authors show that diminished ventral striatal and prefrontal activity in response to anticipated rewards at age 14 in these individuals predicts problematic drug use at age 16.

Changes in White Matter Organization in Adolescent Offspring of Schizophrenia Patients

Schizophrenia is associated with frontostriatal network impairments underlying clinical and cognitive symptoms. We previously found disruptions in anatomical pathways, including the tract connecting the left nucleus accumbens and left dorsolateral prefrontal cortex (DLPFC). Similar deficits are observed in unaffected siblings of schizophrenia patients, indicating that these deficits are linked to a genetic vulnerability for the disorder. Frontostriatal tract disruptions may arise during adolescence, preceding the clinical manifestation of the disorder. However, to date, no studies have been performed to investigate frontostriatal tract connections in adolescents who are at increased familial risk for schizophrenia. In this study, we investigate the impact of familial risk on frontostriatal tract connections using diffusion tensor imaging in 27 adolescent offspring of schizophrenia patients and 32 matched control adolescents, aged 10-18 years. Mean fractional anisotropy (FA) was calculated for the tracts connecting the striatum (caudate nucleus, putamen, nucleus accumbens) and frontal cortex regions (DLPFC, medial orbital frontal cortex, inferior frontal gyrus). As expected, based on siblings data, we found an impact of familial risk on frontostriatal development: schizophrenia offspring showed increased FA in the tracts connecting nucleus accumbens and DLPFC as compared with control adolescents. Moreover, while FA increased across age in control adolescents, it did not in schizophrenia offspring. We did not find differences in FA in other frontostriatal tracts. These results indicate altered development of white matter in subjects who are at familial risk for schizophrenia and may precede frontostriatal white matter alterations in adult schizophrenia patients and siblings.

Neural and behavioral mechanisms of proactive and reactive inhibition

Response inhibition is an important component of adaptive behavior. Substantial prior research has focused on reactive inhibition, which refers to the cessation of a motor response that is already in progress. More recently, a growing number of studies have begun to examine mechanisms underlying proactive inhibition, whereby preparatory processes result in a response being withheld before it is initiated. It has become apparent that proactive inhibition is an essential component of the overall ability to regulate behavior and has implications for the success of reactive inhibition. Moreover, successful inhibition relies on learning the meaning of specific environmental cues that signal when a behavioral response should be withheld. Proactive inhibitory control is mediated by stopping goals, which reflect the desired outcome of inhibition and include information about how and when inhibition should be implemented. However, little is known about the circuits and cellular processes that encode and represent features in the environment that indicate the necessity for proactive inhibition or how these representations are implemented in response inhibition. In this article, we will review the brain circuits and systems involved in implementing inhibitory control through both reactive and proactive mechanisms. We also comment on possible cellular mechanisms that may contribute to inhibitory control processes, noting that substantial further research is necessary in this regard. Furthermore, we will outline a number of ways in which the temporal dynamics underlying the generation of the proactive inhibitory signal may be particularly important for parsing out the neurobiological correlates that contribute to the learning processes underlying various aspects of inhibitory control.

Neural Correlates of Reward Processing in Typical and Atypical Development

Atypically developing children including those born preterm or who have autism spectrum disorder can display difficulties with evaluating rewarding stimuli, which may result from impaired maturation of reward and cognitive control brain regions. During functional magnetic resonance imaging, 58 typically and atypically developing children (6-12 years) participated in a set-shifting task that included the presentation of monetary reward stimuli. In typically developing children, reward stimuli were associated with age-related increases in activation in cognitive control centers, with weaker changes in reward regions. In atypically developing children, no age-related changes were evident. Maturational disturbances in the frontostriatal regions during atypical development may underlie task-based differences in activation.

Future Research Directions in the Positive Valence Systems: Measurement, Development, and Implications for Youth Unipolar Depression

The Positive Valence Systems (PVS) have been introduced by the National Institute of Mental Health as a domain to help organize multiple constructs focusing on reward-seeking behaviors. However, the initial working model for this domain is strongly influenced by adult constructs and measures. Thus, the present review focuses on extending the PVS into a developmental context. Specifically, the review provides some hypotheses about the structure of the PVS, how PVS components may change throughout development, how family history of depression may influence PVS development, and potential means of intervening on PVS function to reduce onsets of depression. Future research needs in each of these areas are highlighted.

Reward Processing and Risk for Depression Across Development

Striatal response to reward has been of great interest in the typical development and psychopathology literatures. These parallel lines of inquiry demonstrate that although typically developing adolescents show robust striatal response to reward, adolescents with major depressive disorder (MDD) and those at high risk for MDD show a blunted response to reward. Understanding how these findings intersect is crucial for the development and application of early preventative interventions in at-risk children, ideally before the sharp increase in the rate of MDD onset that occurs in adolescence. Robust findings relating blunted striatal response to reward and MDD risk are reviewed and situated within a normative developmental context. We highlight the need for future studies investigating longitudinal development, specificity to MDD, and roles of potential moderators and mediators.

Prefrontal cortical thinning in HIV infection is associated with impaired striatal functioning

While cortical thinning has been associated with HIV infection, it is unclear whether this reflects a direct effect of the virus, whether it is related to disruption of subcortical function or whether it is better explained by epiphenomena, such as drug abuse or comorbid medical conditions. The present study investigated the relationship between cortical thickness and subcortical function in HIV+ patients. Specifically, we examined the relationship between prefrontal cortical thickness and striatal function. Twenty-three largely treatment naïve, non-substance abusing HIV+ participants and 19 healthy controls matched for age, gender, and educational status were included. Cortical morphometry was performed using FreeSurfer software analysis. Striatal function was measured during an fMRI stop-signal anticipation task known to engage the striatum. Any cortical regions showing significant thinning were entered as dependent variables into a single linear regression model which included subcortical function, age, CD4 count, and a measure of global cognitive performance as independent predictors. The only cortical region that was significantly reduced after correction for multiple comparisons was the right superior frontal gyrus. Striatal activity was found to independently predict superior frontal gyral cortical thickness. While cortical thinning in HIV infection is likely multifactorial, viral induced subcortical dysfunction appears to play a role.

Annual Research Review: Neural contributions to risk-taking in adolescence--developmental changes and individual differences

BACKGROUND

Risk-taking, which involves voluntary choices for behaviors where outcomes remain uncertain, undergoes considerable developmental changes during childhood, adolescence, and early adulthood. In addition, risk-taking is thought to be a key element of many externalizing disorders, such as ADHD, delinquency, conduct disorder, and substance abuse. In this review, we will discuss the potential adaptive and nonadaptive properties of risk-taking in childhood and adolescence.

FINDINGS

We propose that the changes in brain architecture and function are a crucial element underlying these developmental trajectories. We first identify how subcortical and cortical interactions are important for understanding risk-taking behavior in adults. Next, we show how developmental changes in this network underlie changes in risk-taking behavior. Finally, we explore how these differences can be important for understanding externalizing behavioral disorders in childhood and adolescence.

CONCLUSIONS

We conclude that longitudinal studies are of crucial importance for understanding these developmental trajectories, and many of these studies are currently underway.

The dual systems model: Review, reappraisal, and reaffirmation

According to the dual systems perspective, risk taking peaks during adolescence because activation of an early-maturing socioemotional-incentive processing system amplifies adolescents' affinity for exciting, pleasurable, and novel activities at a time when a still immature cognitive control system is not yet strong enough to consistently restrain potentially hazardous impulses. We review evidence from both the psychological and neuroimaging literatures that has emerged since 2008, when this perspective was originally articulated. Although there are occasional exceptions to the general trends, studies show that, as predicted, psychological and neural manifestations of reward sensitivity increase between childhood and adolescence, peak sometime during the late teen years, and decline thereafter, whereas psychological and neural reflections of better cognitive control increase gradually and linearly throughout adolescence and into the early 20s. While some forms of real-world risky behavior peak at a later age than predicted, this likely reflects differential opportunities for risk-taking in late adolescence and young adulthood, rather than neurobiological differences that make this age group more reckless. Although it is admittedly an oversimplification, as a heuristic device, the dual systems model provides a far more accurate account of adolescent risk taking than prior models that have attributed adolescent recklessness to cognitive deficiencies.

Diminishing striatal activation across adolescent development during reward anticipation in offspring of schizophrenia patients

Schizophrenia is a severe psychiatric disorder associated with impaired fronto-striatal functioning. Similar deficits are observed in unaffected siblings of patients, indicating that these deficits are linked to a familial risk for the disorder. Fronto-striatal deficits may arise during adolescence and precede clinical manifestation of the disorder. However, the development of the fronto-striatal network in adolescents at increased familial risk for schizophrenia is still poorly understood. In this cross-sectional study, we investigate the impact of familial risk on fronto-striatal functioning across age related to reward anticipation and receipt in 25 adolescent offspring of schizophrenia patients (SZ offspring) and 36 age-matched healthy controls (range 10-19years). Subjects performed a reward task while being scanned with functional MRI. Overall response times and the amount of money won did not differ between the groups. Striatal activation during reward anticipation decreased across age in the SZ offspring, while it did not in the healthy controls. Activation in the orbitofrontal cortex during reward receipt did not differ between the groups. These results, taken together with data from adult schizophrenia patients and their siblings, indicate that the diminishing striatal activation across adolescence may signify a familial vulnerability for schizophrenia.

Learning to play it safe (or not): stable and evolving neural responses during adolescent risky decision-making

Adolescent decision-making is a topic of great public and scientific interest. However, much of the neuroimaging research in this area contrasts only one facet of decision-making (e.g., neural responses to anticipation or receipt of monetary rewards). Few studies have directly examined the processes that occur immediately before making a decision between two options that have varied and unpredictable potential rewards and penalties. Understanding adolescent decision-making from this vantage point may prove critical to ameliorating risky behavior and improving developmental outcomes. In this study, participants aged 14-16 years engaged in a driving simulation game while undergoing fMRI. Results indicated activity in ventral striatum preceded risky decisions and activity in right inferior frontal gyrus (rIFG) preceded safe decisions. Furthermore, participants who reported higher sensation-seeking and sensitivity to reward and punishment demonstrated lower rIFG activity during safe decisions. Finally, over successive games, rIFG activity preceding risky decisions decreased, whereas thalamus and caudate activity increased during positive feedback (taking a risk without crashing). These results indicate that regions traditionally associated with reward processing and inhibition not only drive risky decision-making in the moment but also contribute to learning about risk tradeoffs during adolescence.

HIV infection results in ventral-striatal reward system hypo-activation during cue processing

OBJECTIVE

Functional MRI has thus far demonstrated that HIV has an impact on frontal-striatal systems involved in executive functioning. The potential impact of HIV on frontal-striatal systems involved in reward processing has yet to be examined by functional MRI. This study therefore aims to investigate the effects of HIV infection on reward processing by examining the function of the ventral-striatal reward system during a monetary incentive delay task.

DESIGN

This is a cross-sectional case-control study.

METHODS

Eighteen combined antiretroviral therapy-naive HIV-positive (HIV+) participants, as well as 16 matched healthy controls, performed a monetary incentive delay task. This paradigm assesses behaviour as well as functional brain activity-associated reward anticipation and reward outcome.

RESULTS

HIV+ participants showed a general decrease in activation associated with both neutral as well as potentially rewarding cues in their ventral striatum. We found normal activity related to reward outcome in the orbito-frontal cortex. Despite HIV+ participants' reaction times being significantly slower when independently measured from the reward paradigm, this performance deficit normalized during the performance of the reward task.

CONCLUSION

HIV caused a decrease in activity during cue processing in the ventral striatum, with normal cortical functioning during reward outcome processing. Our results therefore suggest that HIV not only has an impact on fronto-striatal systems involved in executive functioning, but also has a direct impact on the function of the ventral-striatal reward system.

The role of stop-signal probability and expectation in proactive inhibition

The subjective belief of what will happen plays an important role across many cognitive domains, including response inhibition. However, tasks that study inhibition do not distinguish between the processing of objective contextual cues indicating stop-signal probability and the subjective expectation that a stop-signal will or will not occur. Here we investigated the effects of stop-signal probability and the expectation of a stop-signal on proactive inhibition. Twenty participants performed a modified stop-signal anticipation task while being scanned with functional magnetic resonance imaging. At the beginning of each trial, the stop-signal probability was indicated by a cue (0% or > 0%), and participants had to indicate whether they expected a stop-signal to occur (yes/no/don't know). Participants slowed down responding on trials with a > 0% stop-signal probability, but this proactive response slowing was even greater when they expected a stop-signal to occur. Analyses were performed in brain regions previously associated with proactive inhibition. Activation in the striatum, supplementary motor area and left dorsal premotor cortex during the cue period was increased when participants expected a stop-signal to occur. In contrast, activation in the right inferior frontal gyrus and right inferior parietal cortex activity during the stimulus-response period was related to the processing of contextual cues signalling objective stop-signal probability, regardless of expectation. These data show that proactive inhibition depends on both the processing of objective contextual task information and the subjective expectation of stop-signals.

Impact of aging on frontostriatal reward processing

Healthy aging is associated with a progressive decline across a range of cognitive functions. An important factor underlying this decline may be the age-related impairment in stimulus-reward processing. Several studies have investigated age-related effects, but compared young versus old subjects. This is the first study to investigate the effect of aging on brain activation during reward processing within a continuous segment of the adult life span. We scanned 49 healthy adults aged 40-70 years, using functional MRI. We adopted a simple reward task, which allowed separate evaluation of neural responses to reward anticipation and receipt. The effect of reward on performance accuracy and speed was not related to age, indicating that all subjects could perform the task correctly. We identified a whole-brain significant age-related decline of ventral striatum activation during reward anticipation as compared to neutral anticipation. Importantly, the specificity of this finding was underscored by the observation that there was no general decline in activation during anticipation. Activation in the ventral striatum increased with age during reward receipt as compared to receiving neutral outcome. Finally, activation in the ventromedial prefrontal cortex during outcome was not affected by age. Our data demonstrate that the typical shift in striatal activation from reward receipt to reward anticipation in young adults disappears with healthy aging. These changes are consistent the well-ocumented age-related decline of striatal dopamine availability, and may provide a stepping stone for further research of age-related neurodegenerative diseases.