Adolescence and Reward: Making Sense of Neural and Behavioral Changes Amid the Chaos

Electrical brain activations in preadolescents during a probabilistic reward-learning task reflect cognitive processes and behavioral strategy

Both adults and children learn through feedback which environmental events and choices are associated with higher probability of reward, an ability thought to be supported by the development of fronto-striatal reward circuits. Recent developmental studies have applied computational models of reward learning to investigate such learning in children. However, tasks and measures effective for assaying the cascade of reward-learning neural processes in children have been limited. Using a child-version of a probabilistic reward-learning task while recording event-related-potential (ERP) measures of electrical brain activity, this study examined key processes of reward learning in preadolescents (8-12 years old; n=30), namely: (1) reward-feedback sensitivity, as measured by the early-latency, reward-related, frontal ERP positivity, (2) rapid attentional shifting of processing toward favored visual stimuli, as measured by the N2pc component, and (3) longer-latency attention-related responses to reward feedback as a function of behavioral strategies (i.e., Win-Stay-Lose-Shift), as measured by the central-parietal P300. Consistent with our prior work in adults, the behavioral findings indicate preadolescents can learn stimulus-reward outcome associations, but at varying levels of performance. Neurally, poor preadolescent learners (those with slower learning rates) showed greater reward-related positivity amplitudes relative to good learners, suggesting greater reward-feedback sensitivity. We also found attention shifting towards to-be-chosen stimuli, as evidenced by the N2pc, but not to more highly rewarded stimuli as we have observed in adults. Lastly, we found the behavioral learning strategy (i.e., Win-Stay-Lose-Shift) reflected by the feedback-elicited parietal P300. These findings provide novel insights into the key neural processes underlying reinforcement learning in preadolescents.

Task-Rest Reconfiguration Efficiency of the Reward Network Across Adolescence and Its Association With Early Life Stress and Depressive Symptoms

OBJECTIVE

Adolescents face significant changes in many domains of their daily lives that require them to flexibly adapt to changing environmental demands. To shift efficiently among various goals, adolescents must reconfigure their brains, disengaging from previous tasks and engaging in new activities.

METHOD

To examine this reconfiguration, we obtained resting-state and task-based functional magnetic resonance imaging (fMRI) scans in a community sample of 164 youths. We assessed the similarity of functional connectivity (FC) of the reward network between resting state and a reward-processing state, indexing the degree of reward network reconfiguration required to meet task demands. Given research documenting relations among reward network function, early life stress (ELS), and adolescent depression, we examined the association of reconfiguration efficiency with age across adolescence, the moderating effect of ELS on this association, and the relation between reconfiguration efficiency and depressive symptoms.

RESULTS

We found that older adolescents showed greater reconfiguration efficiency than younger adolescents and, furthermore, that this age-related association was moderated by the experience of ELS.

CONCLUSION

These findings suggest that reconfiguration efficiency of the reward network increases over adolescence, a developmental pattern that is attenuated in adolescents exposed to severe ELS. In addition, even after controlling for the effects of age and exposure to ELS, adolescents with higher levels of depressive symptoms exhibited greater reconfiguration efficiency, suggesting that they have brain states at rest that are more strongly optimized for reward processing than do asymptomatic youth.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science.

Disproportionate neuroanatomical effects of DCC haploinsufficiency in adolescence compared with adulthood: links to dopamine, connectivity, covariance, and gene expression brain maps in mice

BACKGROUND

Critical adolescent neural refinement is controlled by the DCC (deleted in colorectal cancer) protein, a receptor for the netrin-1 guidance cue. We sought to describe the effects of reduced DCC on neuroanatomy in the adolescent and adult mouse brain.

METHODS

We examined neuronal connectivity, structural covariance, and molecular processes in a DCC-haploinsufficient mouse model, compared with wild-type mice, using new, custom analytical tools designed to leverage publicly available databases from the Allen Institute.

RESULTS

We included 11 DCC-haploinsufficient mice and 16 wild-type littermates. Neuroanatomical effects of DCC haploinsufficiency were more severe in adolescence than adulthood and were largely restricted to the mesocorticolimbic dopamine system. The latter finding was consistent whether we identified the regions of the mesocorticolimbic dopamine system a priori or used connectivity data from the Allen Brain Atlas to determine de novo where these dopamine axons terminated. Covariance analyses found that DCC haploinsufficiency disrupted the coordinated development of the brain regions that make up the mesocorticolimbic dopamine system. Gene expression maps pointed to molecular processes involving the expression of DCC, UNC5C (encoding DCC's co-receptor), and NTN1 (encoding its ligand, netrin-1) as underlying our structural findings.

LIMITATIONS

Our study involved a single sex (males) at only 2 ages.

CONCLUSION

The neuroanatomical phenotype of DCC haploinsufficiency described in mice parallels that observed in DCC-haploinsufficient humans. It is critical to understand the DCC-haploinsufficient mouse as a clinically relevant model system.

Rewiring the future: drugs abused in adolescence may predispose to mental illness in adult life by altering dopamine axon growth

Adolescence is a period of increased exploration and novelty-seeking, which includes new social behaviors, as well as drug experimentation, often spurred on by peer pressure. This is unfortunate, as the immature state of the adolescent brain makes it particularly susceptible to the negative developmental impact of drug use. During adolescence, dopamine terminals, which have migrated from the ventral tegmental area, pause in the nucleus accumbens, before segregating by either forming local connections or growing towards the prefrontal cortex (PFC). This developmentally late and lengthy process renders adolescent dopamine axon pathfinding vulnerable to disruption by substance use. Indeed, exposure to stimulant drugs in adolescent male mice, but not females, triggers dopamine axons to mistarget the nucleus accumbens and to grow ectopically to the PFC. Some evidence suggests that at this novel site, the functional organization of the ectopic dopamine axons mirrors that of the intended target. The structural rewiring dysregulates local synaptic connectivity, leading to poor impulse control ability, deficits of which are a core symptom of substance-use disorders. In the present commentary, we argue that different substances of abuse induce dopamine mistargeting events with the off-target trajectory prescribed by the type of drug, leading to psychiatric outcomes later in life.

Neuroscience-informed classification of prevention interventions in substance use disorders: An RDoC-based approach

Neuroscience has contributed to uncover the mechanisms underpinning substance use disorders (SUD). The next frontier is to leverage these mechanisms as active targets to create more effective interventions for SUD treatment and prevention. Recent large-scale cohort studies from early childhood are generating multiple levels of neuroscience-based information with the potential to inform the development and refinement of future preventive strategies. However, there are still no available well-recognized frameworks to guide the integration of these multi-level datasets into prevention interventions. The Research Domain Criteria (RDoC) provides a neuroscience-based multi-system framework that is well suited to facilitate translation of neurobiological mechanisms into behavioral domains amenable to preventative interventions. We propose a novel RDoC-based framework for prevention science and adapted the framework for the existing preventive interventions. From a systematic review of randomized controlled trials using a person-centered drug/alcohol preventive approach for adolescents, we identified 22 unique preventive interventions. By teasing apart these 22 interventions into the RDoC domains, we proposed distinct neurocognitive trajectories which have been recognized as precursors or risk factors for SUDs, to be targeted, engaged and modified for effective addiction prevention.

Neurocognitive factors predicting BMI changes from adolescence to young adulthood

OBJECTIVE

The objective of this study was to assess whether inhibitory task performance in adolescence could be prospectively related to weight gain in young adulthood. We proposed that this association would differ according to the BMI group in adolescence.

METHODS

A total of 318 adolescents performed the anti-saccade task, and 530 completed the Stroop test. Accuracy and reaction time were assessed for each incentive type (neutral, loss, and reward) in the anti-saccade task and for each trial type (control and incongruent trials) in the Stroop test. Changes in the BMI z score (∆BMI z score) from adolescence to young adulthood were calculated.

RESULTS

The relationship between the BMI z score and the anti-saccade task accuracy showed an effect on the ∆BMI z score (β = -0.002, p < 0.05). The neutral and loss accuracies were related to ∆BMI z score in the groups with overweight (all β = -0.004, p = 0.05) and obesity (β = -0.006 and β = -0.005, p < 0.01). The interaction between adolescents' BMI z score with control (β = -0.312, p < 0.001) and incongruent (β = -0.384, p < 0.001) trial reaction times showed an effect on the ∆BMI z score. Control (β = 0.730, p = 0.036) and incongruent (β = 0.535, p = 0.033) trial reaction times were related to ∆BMI z score in the group with overweight.

CONCLUSIONS

Our findings support the hypothesis that cognitive vulnerability could predict the BMI gain from adolescence to young adulthood.

Sex and pubertal variation in reward-related behavior and neural activation in early adolescents

This study aimed to characterize the role of sex and pubertal markers in reward motivation behavior and neural processing in early adolescence. We used baseline and two-year follow-up data from the Adolescent Brain and Cognitive DevelopmentSM study (15844 observations; 52% from boys; age 9-13). Pubertal development was measured with parent-reported Pubertal Development Scale, and DHEA, testosterone, and estradiol levels. Reward motivation behavior and neural processing at anticipation and feedback stages were assessed with the Monetary Incentive Delay task. Boys had higher reward motivation than girls, demonstrating greater accuracy difference between reward and neutral trials and higher task earnings. Girls had lower neural activation during reward feedback than boys in the nucleus accumbens, caudate, rostral anterior cingulate, medial orbitofrontal cortex, superior frontal gyrus and posterior cingulate. Pubertal stage and testosterone levels were positively associated with reward motivation behavior, although these associations changed when controlling for age. There were no significant associations between pubertal development and neural activation during reward anticipation and feedback. Sex differences in reward-related processing exist in early adolescence, signaling the need to understand their impact on typical and atypical functioning as it unfolds into adulthood.

Dopaminergic signaling regulates microglial surveillance and adolescent plasticity in the frontal cortex

Adolescence is a sensitive period for frontal cortical development and cognitive maturation. The dopaminergic (DA) mesofrontal circuit is particularly malleable in response to changes in adolescent experience and DA activity. However, the cellular mechanisms engaged in this plasticity remain unexplored. Here, we report that microglia, the innate immune cells of the brain, are uniquely sensitive to adolescent mesofrontal DA signaling. Longitudinal in vivo two-photon imaging in mice shows that frontal cortical microglia respond dynamically to plasticity-inducing behavioral or optogenetic DA axon stimulation with increased parenchymal and DA bouton surveillance. Microglial-axon contact precedes new bouton formation, and both D1 and D2-type DA receptors regulate microglial-bouton interactions and axonal plasticity. Moreover, D2 antagonism in adults reinstates adolescent plasticity, including increased microglial surveillance and new DA bouton formation. Our results reveal that DA signaling regulates microglial surveillance and axonal plasticity uniquely in the adolescent frontal cortex, presenting potential interventions for restoring plasticity in the adult brain.

Development and psychometric analysis of the smombie scale for adolescents

PURPOSE

Adolescent pedestrian accidents are increasing because of the "smombie" phenomenon, referring to pedestrians who are distracted by their smartphones and become unaware of their surroundings. In the field of nursing, this phenomenon can negatively affect adolescents' health and well-being. We developed the "smombie scale for adolescents" and examined its psychometric properties.

DESIGN AND METHODS

We revised five items and the response scale of an existing smombie scale for adults based on cognitive interviews and content validity test, and included guiding descriptions for adolescents. Using the revised scale, we surveyed 430 adolescents from South Korea to assess construct validity through confirmatory factor analysis. To review group validity, a logistic regression was conducted using responses to the item on whether participants experienced accidents related to smartphone usage on the street or sidewalk.

RESULTS

The 15 items in the four-factor structure, which was validated using confirmatory factor analysis, demonstrated: a chi-square value (p) of 232.63 (< 0.001), root mean square error of approximation of 0.06, goodness of fit index of 0.93, and Tucker-Lewis index of 0.94. The scale's Cronbach's α was 0.85, indicating good internal consistency. Logistic regression results considering actual accident occurrence showed that Factor 1 (perceived risk) and Factor 3 (pending instant message) were significantly correlated with smombie-related accidents.

CONCLUSIONS

The smombie scale for adolescents demonstrated adequate construct and group validity, and good reliability.

PRACTICE IMPLICATIONS

Its application can yield valuable insights into the effectiveness of pediatric nurses' educational and preventative efforts related to the smombie phenomenon in adolescents.

Cocaine reward and reinstatement in adolescent versus adult rodents

Adolescence is a critical juncture when initiation of drug use intersects with profound developmental changes in the brain. Adolescent drug use increases the risk to develop substance use disorders (SUDs) later in life, but the mechanisms that confer this vulnerability are not understood. SUDs are defined by cycles of use, abstinence, and relapse. Intense craving during drug-free periods is often triggered by cues and environmental contexts associated with previous use. In contrast to our understanding of stimuli that elicit craving and relapse in adults, the behavioral processes that occur during periods of abstinence and relapse in adolescents are poorly understood. The current mini-review will summarize findings from preclinical rodent studies that used cocaine conditioned place preference and operant cocaine self-administration to examine subsequent effects on reward, relapse and incubation of craving.

Gains and Losses: Resilience to Social Defeat Stress in Adolescent Female Mice

BACKGROUND

Adolescence is a unique period of psychosocial growth during which social adversity can negatively influence mental health trajectories. Understanding how adolescent social stress impacts males and females and why some individuals are particularly affected is becoming increasingly urgent. Social defeat stress models for adolescent male mice have been effective in reproducing some physical/psychological aspects of bullying. Designing a model suitable for females has proven challenging.

METHODS

We report a version of the adolescent male accelerated social defeat stress (AcSD) paradigm adapted for females. Early adolescent C57BL/6J female mice (N = 107) were exposed to our modified AcSD procedure twice a day for 4 days and categorized as resilient or susceptible based on a social interaction test 24 hours later. Mice were then assessed for changes in Netrin-1/DCC guidance cue expression in dopamine systems, for inhibitory control in adulthood using the Go/No-Go task, or for alterations in dopamine connectivity organization in the matured prefrontal cortex.

RESULTS

Most adolescent females showed protection against stress-induced social avoidance, but in adulthood, these resilient females developed inhibitory control deficits and showed diminution of prefrontal cortex presynaptic dopamine sites. Female mice classified as susceptible were protected against cognitive and dopaminergic alterations. AcSD did not alter Netrin-1/DCC in early adolescent females, contrary to previous findings with males.

CONCLUSIONS

Preserving prosocial behavior in adolescent females may be important for survival advantage but seems to come at the price of developing persistent cognitive and dopamine deficiencies. The female AcSD paradigm produced findings comparable to those found in males, allowing mechanistic investigation in both sexes.

Divergent reward cue representations in the prefrontal cortex drive reward motivation in adolescence and adulthood

Alterations in motivation and reward-seeking are a transdiagnostic feature of numerous psychiatric disorders that commonly emerge in adolescence, including depression, obsessive- compulsive disorder, and attention deficit hyperactivity disorder. During adolescence, reward motivation is naturally heightened, compared to adulthood, but the underlying mechanisms are not well understood. The medial prefrontal cortex (mPFC) is a late developing brain region that regulates reward learning and motivation and is still maturing in adolescence. The mPFC modulates reward-motivated behaviors in adults, and has been hypothesized to be responsible for adolescents' inability to suppress reward-seeking and impulsive behaviors. Using 2-photon imaging of the mPFC and an active reward task, we demonstrate that both the adult and adolescent mPFC encode reward-predictive cues, with distinct neuronal populations encoding rewarded and unrewarded cues. In adolescence the mPFC is hyper-responsive to reward cues and recruits a larger population of neurons to encode reward predictive cues. Furthermore, in the adolescent mPFC, representations of unrewarded cues are attenuated, compared to the adult mPFC, which may tip the balance of action toward reward-seeking. Differences in neuronal responses to rewarded and unrewarded cues were observed in both GABAergic and glutamatergic neurons, with GABAergic inhibition causing disparate effects in adolescents compared to adults. Together our findings identify differences in the functional properties of mPFC microcircuits in adolescents that may underlie differences in reward-seeking behavior and the ability to adaptively suppress reward seeking.

Adolescent neurostimulation of dopamine circuit reverses genetic deficits in frontal cortex function

Dopamine system dysfunction is implicated in adolescent-onset neuropsychiatric disorders. Although psychosis symptoms can be alleviated by antipsychotics, cognitive symptoms remain unresponsive and novel paradigms investigating the circuit substrates underlying cognitive deficits are critically needed. The frontal cortex and its dopaminergic input from the midbrain are implicated in cognitive functions and undergo maturational changes during adolescence. Here, we used mice carrying mutations in Arc or Disc1 to model mesofrontal dopamine circuit deficiencies and test circuit-based neurostimulation strategies to restore cognitive functions. We found that in a memory-guided spatial navigation task, frontal cortical neurons were activated coordinately at the decision-making point in wild-type but not Arc-/- mice. Chemogenetic stimulation of midbrain dopamine neurons or optogenetic stimulation of frontal cortical dopamine axons in a limited adolescent period consistently reversed genetic defects in mesofrontal innervation, task-coordinated neuronal activity, and memory-guided decision-making at adulthood. Furthermore, adolescent stimulation of dopamine neurons also reversed the same cognitive deficits in Disc1+/- mice. Our findings reveal common mesofrontal circuit alterations underlying the cognitive deficits caused by two different genes and demonstrate the feasibility of adolescent neurostimulation to reverse these circuit and behavioral deficits. These results may suggest developmental windows and circuit targets for treating cognitive deficits in neurodevelopmental disorders.

Risk Assessment of Maladaptive Behaviors in Adolescents: Nutrition, Screen Time, Prenatal Exposure, Childhood Adversities - Adolescent Brain Cognitive Development Study

PURPOSE

We aimed to identify significant contributing factors to the risk of maladaptive behaviors, such as alcohol use disorder or obesity, in children. To achieve this, we utilized the extensive adolescent brain cognitive development data set, which encompasses a wide range of environmental, social, and nutritional factors.

METHODS

We divided our sample into equal sets (test, validation; n = 3,415 each). On exploratory factor analysis, six factor domains were identified as most significant (fat/sugar intake, screen time, and prenatal alcohol exposure, parental aggressiveness, hyperactivity, family violence, parental education, and family income) and used to stratify the children into low- (n = 975), medium- (n = 967), high- (n = 977) risk groups. Regression models were used to analyze the relationship between identified risk groups, and differences in reward sensitivity, and behavioral problems at 2-year follow-up.

RESULTS

The functional magnetic resonance imaging analyses showed reduced activation in several brain regions during reward or loss anticipation in high/medium-risk (vs. low-risk) children on a monetary incentive delay task. High-risk children exhibited heightened middle frontal cortex activity when receiving large rewards. They also displayed increased impulsive and motivated reward-seeking behaviors, along with behavioral problems. These findings replicated in our validation set, and a negative correlation between middle frontal cortexthickness and impulsivity behavior was observed in high-risk children.

DISCUSSION

Our findings show altered reward function and increased impulsiveness in high-risk adolescents. This study has implications for early risk identification and the development of prevention strategies for maladaptive behaviors in children, particularly those at high risk.

Δ9-Tetrahydrocannabinol does not upregulate an aversive dopamine receptor mechanism in adolescent brain unlike in adults

Earlier age of cannabis usage poses higher risk of Cannabis Use Disorder and adverse consequences, such as addiction, anxiety, dysphoria, psychosis, largely attributed to its principal psychoactive component, Δ9-tetrahydrocannabinol (THC) and altered dopaminergic function. As dopamine D1-D2 receptor heteromer activation causes anxiety and anhedonia, this signaling complex was postulated to contribute to THC-induced affective symptoms. To investigate this, we administered THC repeatedly to adolescent monkeys and adolescent or adult rats. Drug-naïve adolescent rat had lower striatal densities of D1-D2 heteromer compared to adult rat. Repeated administration of THC to adolescent rat or adolescent monkey did not alter D1-D2 heteromer expression in nucleus accumbens or dorsal striatum but upregulated it in adult rat. Behaviourally, THC-treated adult, but not adolescent rat manifested anxiety and anhedonia-like behaviour, with elevated composite negative emotionality scores that correlated with striatal D1-D2 density. THC modified downstream markers of D1-D2 activation in adult, but not adolescent striatum. THC administered with cannabidiol did not alter D1-D2 expression. In adult rat, co-administration of CB1 receptor (CB1R) inverse agonist with THC attenuated D1-D2 upregulation, implicating cannabinoids in the regulation of striatal D1-D2 heteromer expression. THC exposure revealed an adaptable age-specific, anxiogenic, anti-reward mechanism operant in adult striatum but deficient in adolescent rat and monkey striatum that may confer increased sensitivity to THC reward in adolescence while limiting its negative effects, thus promoting continued use and increasing vulnerability to long-term adverse cannabis effects.

Circadian, Reward, and Emotion Systems in Teens prospective longitudinal study: protocol overview of an integrative reward-circadian rhythm model of first onset of bipolar spectrum disorder in adolescence

BACKGROUND

Bipolar spectrum disorders (BSDs) are associated with a heightened sensitivity to rewards and elevated reward-related brain function in cortico-striatal circuitry. A separate literature documents social and circadian rhythm disruption in BSDs. Recently, integrated reward-circadian models of BSDs have been proposed. These models draw on work indicating that the two systems influence each other and interact to affect mood functioning. When dysregulated, reward and circadian system signaling may combine to form a positive feedback loop, whereby dysregulation in one system exacerbates dysregulation in the other. Project CREST (Circadian, Reward, and Emotion Systems in Teens) provides a first systematic test of reward-circadian dysregulation as a synergistic and dynamic vulnerability for first onset of BSD and increases in bipolar symptoms during adolescence.

METHODS

This NIMH-funded R01 study is a 3-year prospective, longitudinal investigation of approximately 320 community adolescents from the broader Philadelphia area, United States of America. Eligible participants must be 13-16 years old, fluent in English, and without a prior BSD or hypomanic episode. They are being selected along the entire dimension of self-reported reward responsiveness, with oversampling at the high tail of the dimension in order to increase the likelihood of BSD onsets. At Times 1-6, every 6 months, participants will complete assessments of reward-relevant and social rhythm disruption life events and self-report and diagnostic assessments of bipolar symptoms and episodes. Yearly, at Times 1, 3, and 5, participants also will complete self-report measures of circadian chronotype (morningness-eveningness) and social rhythm regularity, a salivary dim light melatonin onset (DLMO) procedure to assess circadian phase, self-report, behavioral, and neural (fMRI) assessments of monetary and social reward responsiveness, and a 7-day ecological momentary assessment (EMA) period. During each EMA period, participants will complete continuous measures of sleep/wake and activity (actigraphy), a daily sleep diary, and three within-day (morning, afternoon, evening) measures of life events coded for reward-relevance and social rhythm disruption, monetary and social reward responsiveness, positive and negative affect, and hypo/manic and depressive symptoms. The fMRI scan will occur on the day before and the DLMO procedure will occur on the first evening of the 7-day EMA period.

DISCUSSION

This study is an innovative integration of research on multi-organ systems involved in reward and circadian signaling in understanding first onset of BSD in adolescence. It has the potential to facilitate novel pharmacological, neural, and behavioral interventions to treat, and ideally prevent, bipolar conditions.

Dopamine transporter blockade during adolescence increases adult dopamine function, impulsivity, and aggression

Sensitive developmental periods shape neural circuits and enable adaptation. However, they also engender vulnerability to factors that can perturb developmental trajectories. An understanding of sensitive period phenomena and mechanisms separate from sensory system development is still lacking, yet critical to understanding disease etiology and risk. The dopamine system is pivotal in controlling and shaping adolescent behaviors, and it undergoes heightened plasticity during that time, such that interference with dopamine signaling can have long-lasting behavioral consequences. Here we sought to gain mechanistic insight into this dopamine-sensitive period and its impact on behavior. In mice, dopamine transporter (DAT) blockade from postnatal (P) day 22 to 41 increases aggression and sensitivity to amphetamine (AMPH) behavioral stimulation in adulthood. Here, we refined this sensitive window to P32-41 and identified increased firing of dopaminergic neurons in vitro and in vivo as a neural correlate to altered adult behavior. Aggression can result from enhanced impulsivity and cognitive dysfunction, and dopamine regulates working memory and motivated behavior. Hence, we assessed these behavioral domains and found that P32-41 DAT blockade increases impulsivity but has no effect on cognition, working memory, or motivation in adulthood. Lastly, using optogenetics to drive dopamine neurons, we find that increased VTA but not SNc dopaminergic activity mimics the increase in impulsive behavior in the Go/NoGo task observed after adolescent DAT blockade. Together our data provide insight into the developmental origins of aggression and impulsivity that may ultimately improve diagnosis, prevention, and treatment strategies for related neuropsychiatric disorders.

Adolescent neurostimulation of dopamine circuit reverses genetic deficits in frontal cortex function

Dopamine system dysfunction is commonly implicated in adolescent-onset neuropsychiatric disorders. Although psychosis symptoms can be alleviated by antipsychotics, cognitive symptoms remain unresponsive to such pharmacological treatments and novel research paradigms investigating the circuit substrates underlying cognitive deficits are critically needed. The frontal cortex and its dopaminergic input from the midbrain are implicated in cognitive functions and undergo maturational changes during adolescence. Here, we used mice carrying mutations in the Arc or DISC1 genes to model mesofrontal dopamine circuit deficiencies and test circuit-based neurostimulation strategies to restore cognitive functions. We found that in a memory-guided spatial navigation task, frontal cortical neurons were activated coordinately at the decision-making point in wild-type but not Arc mutant mice. Chemogenetic stimulation of midbrain dopamine neurons or optogenetic stimulation of frontal cortical dopamine axons in a limited adolescent period consistently reversed genetic defects in mesofrontal innervation, task-coordinated neuronal activity, and memory-guided decision-making at adulthood. Furthermore, adolescent stimulation of dopamine neurons also reversed the same cognitive deficits in DISC1 mutant mice. Our findings reveal common mesofrontal circuit alterations underlying the cognitive deficits caused by two different genes and demonstrate the feasibility of adolescent neurostimulation to reverse these circuit and behavioral deficits. These results may suggest developmental windows and circuit targets for treating cognitive deficits in neurodevelopmental disorders.

Reward and Immune Systems in Emotion (RISE) prospective longitudinal study: Protocol overview of an integrative reward-inflammation model of first onset of major depression in adolescence

Background

Depression is associated with a reduced sensitivity to rewards and low reward-related brain function in cortico-striatal circuitry. A separate literature documents elevated peripheral inflammation in depression. Recently, integrated reward-inflammation models of depression have been proposed. These models draw on work indicating that peripheral inflammatory proteins access the brain, where they lower reward responsiveness. This blunted reward responsiveness is proposed to initiate unhealthy behaviors (substance use, poor diet), as well as sleep disruption and stress generation, which further heighten inflammation. Over time, dysregulation in reward responsiveness and immune signaling may synergize in a positive feedback loop, whereby dysregulation in each system exacerbates dysregulation in the other. Project RISE (Reward and Immune Systems in Emotion) provides a first systematic test of reward-immune dysregulation as a synergistic and dynamic vulnerability for first onset of major depressive disorder and increases in depressive symptoms during adolescence.

Methods

This NIMH-funded R01 study is a 3-year prospective, longitudinal investigation of approximately 300 community adolescents from the broader Philadelphia area, United States of America. Eligible participants must be 13-16 years old, fluent in English, and without a prior major depressive disorder. They are being selected along the entire dimension of self-reported reward responsiveness, with oversampling at the low tail of the dimension in order to increase the likelihood of major depression onsets. At Time 1 (T1), T3, and T5, each a year apart, participants complete blood draws to quantify biomarkers of low-grade inflammation, self-report and behavioral measures of reward responsiveness, and fMRI scans of reward neural activity and functional connectivity. At T1-T5 (with T2 and T4 six months between the yearly sessions), participants also complete diagnostic interviews and measures of depressive symptoms, reward-relevant life events, and behaviors that increase inflammation. Adversity history is assessed at T1 only.

Discussion

This study is an innovative integration of research on multi-organ systems involved in reward and inflammatory signaling in understanding first onset of major depression in adolescence. It has the potential to facilitate novel neuroimmune and behavioral interventions to treat, and ideally prevent, depression.

Interaction of Nicotine and Social reward in group-reared male adolescent rats

Adolescents exhibit great sensitivity to nicotine and social interaction; accordingly, when both stimuli are presented together, they interact to enhance the incentive value of the context in which they occur. Noteworthy, most studies assessing the interaction between nicotine and social reward have used isolated-reared rats. Adolescent isolation is an adverse condition that impacts brain development and behavior, so it is not known if the interaction also occurs in rats without social deprivation. The present study used a conditioned place preference model (CPP) to examine the interaction between nicotine and social reward in group-reared male adolescent rats. At weaning, Wistar rats were randomly assigned to four groups: vehicle, vehicle and a social partner, nicotine (0.1mg/Kg s.c.), and nicotine and a social partner. Conditioning trials occurred on eight consecutive days followed by a test session in which the preference change was assessed. Besides the establishment of CPP, we examined the effects of nicotine on (1) social behaviors during CPP trials and (2) tyrosine hydroxylase (TH) and oxytocin (OT) as markers of changes in the neuronal mechanisms for reward and social affiliation. Similar to previous results, the joint presentation of nicotine and social reward induced CPP, whereas either nicotine or social interaction presented alone did not. This finding coincided with an increase in TH levels observed after nicotine administration only in socially conditioned rats. The interaction between nicotine and social reward is not related to the effects of nicotine on social investigation or social play.

Reappraising the role of dopamine in adolescent risk-taking behavior

Adolescence is characterized by increased risk-taking, which is often ascribed to developmental changes in dopaminergic signaling. Popular models propose that these behaviors are caused by dopamine-induced hypersensitivity to rewards, which overrides adolescents' immature self-control mechanisms. However, these models are often based on oversimplified notions about the workings and functions of dopamine. Here we discuss the relationship between changes in the dopaminergic system and adolescent behavior in light of current theories/models about the functions of dopamine. We show that dopamine is linked to learning, adaptive decision-making under uncertainty, and increased motivation to work for rewards. Thus, changes in the dopaminergic system contribute to the maturation of cognitive control through various mechanisms, contrary to the false dichotomy between reward processing and self-control. Finally, we note that dopamine interacts with a number of other neuromodulator systems, which also change during adolescence, but that have been largely ignored in the field of adolescent development. A full understanding of adolescent behavior will require these neurochemicals and their interactions with dopamine to be taken into account.

Alterations in pain during adolescence and puberty

During adolescence and puberty, alterations in pain, both experimental and clinical, are observed. In addition, adolescents undergo extensive biopsychosocial changes as they transition from childhood to adulthood. However, a better understanding of how the biopsychosocial changes during adolescence impact pain is needed to improve pain management and develop targeted pain interventions for adolescents. This review synthesizes the literature on alterations in pain during adolescence in humans, describes the potential biopsychosocial factors impacting pain during adolescence, and suggests future research directions to advance the understanding of the impact of adolescent development on pain.

Acute and long-term sex-dependent effects of social instability stress on anxiety-like and social behaviours in Wistar rats

Adolescence is a critical time of social learning in which both the quantity and quality of social interactions shape adult behavior and social function. During adolescence, social instability such as disrupting or limiting social interactions can lead to negative life-long effects on mental health and well-being in humans. Animal models on social instability are critically important in understanding those underlying neurobiological mechanisms. However, studies in rats using these models have produced partly inconsistent results and can be difficult to generalize. Here we assessed in a sex and age consistent manner the long-term behavioural consequences of social instability stress (SIS - 1-hr daily isolation and change in cage mate between postnatal day (PD30-45)) in Wistar rats. Female and male rats underwent a battery of tests for anxiety-like, exploratory, and social behaviour over five days beginning either in adolescence (PD46) or in adulthood (PD70). Social instability led to reduced anxiety-like behaviour in the elevated plus maze in both sexes in adolescence and in adulthood. Social interactions were also reduced in rats that underwent SIS - an effect that was independent of sex and age when tested. SIS improved social recognition memory in both sexes whereas a sex-dependent effect was seen in the social novelty preference test where male rats that underwent SIS spent more time in social approach toward a novel peer than toward their cage mate. In comparison, control male and female groups did not differ in this test, in time spent with novel versus the cage mate. Thus, overall, social instability stress in Wistar rats altered the behavioural repertoire, with enduring alterations in social behaviour, enhanced exploratory behaviour, and reduced anxiety-like behaviour. In conclusion, the social instability stress paradigm may better be interpreted as a form of enrichment in Wistar rats than as a stressor.

Alcohol and cannabinoid binges and daily exposure to nicotine in adolescent/young adult rats induce sex-dependent long-term appetitive instrumental learning impairment

Adolescence is a critical developmental period, concerning anatomical, neurochemical and behavioral changes. Moreover, adolescents are more sensitive to the long-term deleterious effects of drug abuse. Binge-like consumption of alcohol and marijuana, along with tobacco smoking, is a dangerous pattern often observed in adolescents during weekends. Nevertheless, the long-term effect of their adolescent co-exposure has not been yet experimentally investigated. Long-Evans adolescent male (n = 20) and female (n = 20) rats from postnatal day 30 (P30) until P60 were daily treated with nicotine (0.3 mg/kg, i.p.), and, on two consecutive 'binging days' per week (for a total of eight times), received an intragastric ethanol solution (3 g/kg) and an intraperitoneal (i.p.) dose of cannabinoid 1/2 receptor agonist WIN55,212-2 (1.2 mg/kg). These rats were tested after treatment discontinuation at > P90 for associative food-rewarded operant learning in the two-lever conditioning chambers for six consecutive days on a fixed ratio 1 (FR1) schedule followed by another six days of daily FR2 schedule testing, after 42 days rest. We found the main effects of sex x treatment interactions in FR1 but not in FR2 experiments. Treated females show attenuated operant responses for food pellets during all FR1 and the FR2 schedule, whilst the treated males show an impairment in FR2 but not in the FR1 schedule. Moreover, the treated females' percentage of learners was significantly lower than female controls in FR1 while treated males were lower than controls in FR2. Our findings suggest that intermittent adolescent abuse of common drugs, such as alcohol and marijuana, and chronic tobacco exposure can cause significant long-term effects on motivation for natural reinforcers later in adulthood in both sexes. Females appear to be sensitive earlier to the deleterious effects of adolescent polydrug abuse, with both sexes having an increased likelihood of developing lifelong brain alterations.

Adolescents' neural reactivity to acute psychosocial stress: dysfunctional regulation habits are linked to temporal gyrus response

Mid-adolescence is a critical time for the development of stress-related disorders and it is associated with significant social vulnerability. However, little is known about normative neural processes accompanying psychosocial stress at this time. Previous research found that emotion regulation strategies critically influence the relationship between stress and the development of psychiatric symptoms during adolescence. Using functional magnetic resonance imaging (fMRI), we examined neural responses to acute stress and analyzed whether the tendency to use adaptive or maladaptive emotion regulation strategies is related to neural and autonomic stress responses. Results show large linear activation increases from low to medium to high stress levels mainly in medial prefrontal, insulae and temporal areas. Caudate and subgenual anterior cingulate cortex, neural areas related to reward and affective valuations, showed linearly decreasing activation. In line with our hypothesis, the current adolescent neural stress profile resembled social rejection and was characterized by pronounced activation in insula, angular and temporal cortices. Moreover, results point to an intriguing role of the anterior temporal gyrus. Stress-related activity in the anterior temporal gyrus was positively related to maladaptive regulation strategies and stress-induced autonomic activity. Maladaptive coping might increase the social threat and reappraisal load of a stressor, relating to higher stress sensitivity of anterior temporal cortices.

Photoperiod Impacts Nucleus Accumbens Dopamine Dynamics

Circadian photoperiod, or day length, changes with the seasons and influences behavior to allow animals to adapt to their environment. Photoperiod is also associated with seasonal rhythms of affective state, as evidenced by seasonality of several neuropsychiatric disorders. Interestingly, seasonality tends to be more prevalent in women for affective disorders such as major depressive disorder and bipolar disorder (BD). However, the underlying neurobiological processes contributing to sex-linked seasonality of affective behaviors are largely unknown. Mesolimbic dopamine input to the nucleus accumbens (NAc) contributes to the regulation of affective state and behaviors. Additionally, sex differences in the mesolimbic dopamine pathway are well established. Therefore, we hypothesize that photoperiod may drive differential modulation of NAc dopamine in males and females. Here, we used fast-scan cyclic voltammetry (FSCV) to explore whether photoperiod can modulate subsecond dopamine signaling dynamics in the NAc core of male and female mice raised in seasonally relevant photoperiods. We found that photoperiod modulates dopamine signaling in the NAc core, and that this effect is sex-specific to females. Both release and uptake of dopamine were enhanced in the NAc core of female mice raised in long, summer-like photoperiods, whereas we did not find photoperiodic effects on NAc core dopamine in males. These findings uncover a potential neural circuit basis for sex-linked seasonality in affective behaviors.

Is loss avoidance differentially rewarding in adolescents versus adults? Differences in ventral striatum and anterior insula activation during the anticipation of potential monetary losses

Avoiding loss is a crucial, adaptive guide to human behavior. While previous developmental research has primarily focused on gaining rewards, less attention has been paid to loss processing and its avoidance. In daily life, it is often unknown how likely an action will result in a loss, making the role of uncertainty in loss processing particularly important. By using functional magnetic resonance imaging, we investigated the influence of varying outcome probabilities (12%, 34%, and 67%) on brain regions implicated in loss processing (ventral striatum (VS), anterior insula (AI)) by comparing 28 adolescents (10-18 years) and 24 adults (22-32 years) during the anticipation of potential monetary loss.Overall, results revealed slower RTs in adolescents compared to adults with both groups being faster in the experimental (monetary condition) vs. control trials (verbal condition). Fastest RTs were observed for the 67% outcome probability in both age groups. An age group × outcome probability interaction effect revealed the greatest differences between the groups for the 12% vs. the 67% outcome probability. Neurally, both age groups demonstrated a higher percent signal change in the VS and AI during the anticipation of potential monetary loss versus the verbal condition. However, adults demonstrated an even greater activation of VS and AI than adolescents during the anticipation of potential monetary loss, but not during the verbal condition. This may indicate that adolescents differ from adults regarding their experience of avoiding losing monetary rewards.

Effects of prenatal opioid exposure on synaptic adaptations and behaviors across development

In this review, we focus on prenatal opioid exposure (POE) given the significant concern for the mental health outcomes of children with parents affected by opioid use disorder (OUD) in the view of the current opioid crisis. We highlight some of the less explored interactions between developmental age and sex on synaptic plasticity and associated behavioral outcomes in preclinical POE research. We begin with an overview of the rich literature on hippocampal related behaviors and plasticity across POE exposure paradigms. We then discuss recent work on reward circuit dysregulation following POE. Additional risk factors such as early life stress (ELS) could further influence synaptic and behavioral outcomes of POE. Therefore, we include an overview on the use of preclinical ELS models where ELS exposure during key critical developmental periods confers considerable vulnerability to addiction and stress psychopathology. Here, we hope to highlight the similarity between POE and ELS on development and maintenance of opioid-induced plasticity and altered opioid-related behaviors where similar enduring plasticity in reward circuits may occur. We conclude the review with some of the limitations that should be considered in future investigations. This article is part of the Special Issue on 'Opioid-induced addiction'.

The role of dopamine and endocannabinoid systems in prefrontal cortex development: Adolescence as a critical period

The prefrontal cortex plays a central role in the control of complex cognitive processes including action control and decision making. It also shows a specific pattern of delayed maturation related to unique behavioral changes during adolescence and allows the development of adult cognitive processes. The adolescent brain is extremely plastic and critically vulnerable to external insults. Related to this vulnerability, adolescence is also associated with the emergence of numerous neuropsychiatric disorders involving alterations of prefrontal functions. Within prefrontal microcircuits, the dopamine and the endocannabinoid systems have widespread effects on adolescent-specific ontogenetic processes. In this review, we highlight recent advances in our understanding of the maturation of the dopamine system and the endocannabinoid system in the prefrontal cortex during adolescence. We discuss how they interact with GABA and glutamate neurons to modulate prefrontal circuits and how they can be altered by different environmental events leading to long-term neurobiological and behavioral changes at adulthood. Finally, we aim to identify several future research directions to help highlight gaps in our current knowledge on the maturation of these microcircuits.

Adolescent sleep and the foundations of prefrontal cortical development and dysfunction

Modern life poses many threats to good-quality sleep, challenging brain health across the lifespan. Curtailed or fragmented sleep may be particularly damaging during adolescence, when sleep disruption by delayed chronotypes and societal pressures coincides with our brains preparing for adult life via intense refinement of neural connectivity. These vulnerabilities converge on the prefrontal cortex, one of the last brain regions to mature and a central hub of the limbic-cortical circuits underpinning decision-making, reward processing, social interactions and emotion. Even subtle disruption of prefrontal cortical development during adolescence may therefore have enduring impact. In this review, we integrate synaptic and circuit mechanisms, glial biology, sleep neurophysiology and epidemiology, to frame a hypothesis highlighting the implications of adolescent sleep disruption for the neural circuitry of the prefrontal cortex. Convergent evidence underscores the importance of acknowledging, quantifying and optimizing adolescent sleep's contributions to normative brain development and to lifelong mental health.

Real-World Exploration Increases Across Adolescence and Relates to Affect, Risk Taking, and Social Connectivity

Cross-species research suggests that exploratory behaviors increase during adolescence and relate to the social, affective, and risky behaviors characteristic of this developmental stage. However, how these typical adolescent behaviors manifest and relate in real-world settings remains unclear. Using geolocation tracking to quantify exploration—variability in daily movement patterns—over a 3-month period in 58 adolescents and adults (ages 13–27) in New York City, we investigated whether daily exploration varied with age and whether exploration related to social connectivity, risk taking, and momentary positive affect. In our cross-sectional sample, we found an association between daily exploration and age, with individuals near the transition to legal adulthood exhibiting the highest exploration levels. Days of higher exploration were associated with greater positive affect irrespective of age. Higher mean exploration was associated with greater social connectivity in all participants but was linked to higher risk taking selectively among adolescents. Our results highlight the interplay of exploration and socioemotional behaviors across development and suggest that societal norms may modulate their expression in naturalistic contexts.

Sleepy and Secluded: Sleep Disturbances are Associated With Connectedness in Early Adolescent Social Networks

Studies in adults suggest that sleep disturbances predict poorer socioemotional skills and impaired social interactions. However, little is known regarding how sleep disturbances are associated with social processes during adolescence, a period when both sleep neurobiology and social relationships are undergoing dramatic developmental changes. The current study examined associations among sleep disturbances and peer connectedness in a sample of middle-school students (N = 213, 11-15 years old, 57% female) using a social network approach. Findings suggested that youth with greater sleep disturbances reported having fewer social connections, were rated as a social connection by fewer peers, and were less likely to have reciprocated nominations, even after controlling for sociodemographic characteristics and mental health symptoms.

Positive valence systems in youth anxiety development: A scoping review

Research on pathophysiological mechanisms supporting anxiety development in youth has traditionally focused on the role of threat systems. However, emerging research suggests that the positive valence system (PVS) may also play a strong and unique role in the development and maintenance of anxiety during childhood and adolescence. To better understand the connection between the PVS and anxiety, this scoping review describes current research spanning multiple units of analysis (i.e., self-report, behavior, neural circuits) linking child and adolescent anxiety and risk for anxiety to various PVS constructs (i.e., positive affect, reward responsiveness, reward learning and decision-making). After screening, 78 peer-reviewed articles and dissertations published between 1998 and May 2021 were included in a qualitative review. Though some consistencies in the literature were found, such as high neural reactivity to incentive anticipation in youth at temperamental risk for social anxiety and blunted positive affect in youth with social anxiety disorder, the literature is largely inconsistent. Inconsistencies could be related to the small number of similar studies, small and homogenous study samples, and variability in methodologies employed in this research. It cannot be confirmed whether findings linking PVS constructs to anxiety are unique to anxiety symptoms or better accounted for by co-occurring depressive symptoms. This review concludes with recommendations for robust future research in this area.

Peer presence increases the prosocial behavior of adolescents by speeding the evaluation of outcomes for others

Peer presence can elicit maladaptive adolescent decision-making, potentially by increasing sensitivity to the rewards one receives. It remains unknown whether peer presence also increases adolescents' sensitivity to others' outcomes, which could have an adaptive effect in contexts allowing pro-social behaviors. Here, we combine social utility modeling and real-time decision process modeling to characterize how peer presence alters adolescents' processing of self and other outcomes. We found that adolescents behaved selfishly when privately allocating monetary rewards for themselves and a peer in an incentive-compatible task. In peer presence, however, adolescents became more altruistic. Real-time decision process estimates collected using computer mouse tracking showed that altruistic behavior was associated with relatively earlier influence of peer-outcomes relative to self-outcomes, and that peer presence sped the influence of peer-outcomes without altering the time at which self-outcomes began to influence the decision process. Our results indicate a mechanism through which peer presence prompts greater prosocial behavior by altering how adolescents process prosocial outcomes.

GENETIC AND ENVIRONMENTAL CONTRIBUTIONS TO POSITIVE AFFECT: INSIGHTS FROM ADOLESCENT TWINS

Disturbances in positive affect and reductions in social reward/interpersonal pleasure are common across a range of clinical disorders and are often related. We examined the relationship between the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS-A), and other measures of positive affect in adolescents in a genetically informative research design. The sample consisted of 177 MZ and 136 same sex DZ twins drawn from a study of adolescent twins (M = 16.4 ± .97 years) who were part of the Wisconsin Twin Project. The self-report questionnaires included the Behavioral Activation Scale (BAS), Psychological Well-Being Scale, revised Early Adolescent Temperament Questionnaire (EATQR) and the adolescent version of the ACIPS (ACIPS-A). Structural equation modeling estimated the relative contribution of genetic and environmental factors to the phenotypic variance in each of the measures. Follow-up bivariate analyses parsed the genetic and environmental contributions to the phenotypic covariances between the ACIPS-A and each of the other measures of positive affect. We found evidence of moderate heritability for the ACIPS-A scale scores. Overall, models specifying additive genetic and unique environmental effects (AE models) were the most parsimonious models for each of the measures. Several of the measures showed moderate positive phenotypic intercorrelations, and all but one of these intercorrelations showed significant partial genetic underpinnings. Moreover, the bivariate biometric analyses indicated that the ACIPS-A also captures unique heritable variation. Thus, the ACIPS-A captures unique heritable contributions to social/interpersonal pleasure, as well as shared genetic variance with other measures of positive affectivity.

Sex-related brain connectivity correlates of compensation in adults with autism: insights into female protection

The male preponderance in autism spectrum disorder (ASD) led to the hypothesis that aspects of female biology are protective against ASD. Females with ASD (ASD-F) report more compensatory behaviors (i.e. "camouflaging") to overcome ASD-related social differences, which may be a mechanism of protection. No studies have examined sex-related brain pathways supporting camouflaging in ASD-F, despite its potential to inform mechanisms underlying the ASD sex bias. We used functional connectivity (FC) to investigate "sex-atypical" and "sex-typical" FC patterns linked to camouflaging in adults with ASD and examined multimodal coherence of findings via structural connectometry. Exploratory associations with cognitive/emotional functioning examined the adaptive nature of FC patterns. We found (i) "sex-atypical" FC patterns linked to camouflaging in the hypothalamus and precuneus and (ii) "sex-typical" patterns in the right anterior cingulate and anterior parahippocampus. Higher hypothalamic FC with a limbic reward cluster also correlated with better cognitive control/emotion recognition. Structural connectometry validated FC results with consistent brain pathways/effect patterns implicated in ASD-F. In summary, "male-typical" and "female-typical" brain connectivity patterns support camouflaging in ASD-F in circuits implicated in reward, emotion, and memory retrieval. "Sex-atypical" results are consistent with fetal steroidogenic/neuroinflammatory hypotheses. However, female genetics/biology may contribute to "female-typical" patterns implicated in camouflaging.

A brief child-friendly reward task reliably activates the ventral striatum in two samples of socioeconomically diverse youth

Adolescence is a period of increased risk-taking behavior, thought to be driven, in part, by heightened reward sensitivity. One challenge of studying reward processing in the field of developmental neuroscience is finding a task that activates reward circuitry, and is short, not too complex, and engaging for youth of a wide variety of ages and socioeconomic backgrounds. In the present study, we tested a brief child-friendly reward task for activating reward circuitry in two independent samples of youth ages 7-19 years old enriched for poverty (study 1: n = 464; study 2: n = 27). The reward task robustly activated the ventral striatum, with activation decreasing from early to mid-adolescence and increasing from mid- to late adolescence in response to reward. This response did not vary by gender, pubertal development, or income-to-needs ratio, making the task applicable for a wide variety of populations. Additionally, ventral striatum activation to the task did not differ between youth who did and did not expect to receive a prize at the end of the task, indicating that an outcome of points alone may be enough to engage reward circuitry. Thus, this reward task is effective for studying reward processing in youth from different socioeconomic backgrounds.

"I Grew Up Amidst Alcohol and Drugs:" a Qualitative Study on the Lived Experiences of Parental Substance Use Among Adults Who Developed Substance Use Disorders Themselves

Experiencing parental substance use (PSU) has been associated with a heightened risk of developing substance use disorders (SUDs) in offspring. The primary goal of this study was to explore perspectives of adult children with lived experience of PSU who also developed SUDs themselves through first-hand experience. This study was conducted in Flanders (Belgium). A qualitative exploratory research design was applied. Seventeen semi-structured interviews were conducted with adult children of parents with SUDs (range: 29-48 years) who themselves had developed SUDs. All interviews were audio-taped and transcribed verbatim. Three overarching themes emerged through thematic analysis: 1) loneliness and neglect in childhood; 2) stigma and the self; and 3) the role of social connection in substance use and recovery. The narratives highlighted the central role of feelings of loneliness, isolation and belonging among children of parents with SUDs in childhood and adulthood. Increasing public awareness on the impact of PSU on children and accessible support is needed to overcome stigma and remove barriers to social inclusion for children of parents with SUDs. Findings may prove valuable in informing policy, program and treatment development aimed at breaking maladaptive intergenerational cycles.

Social preference in Roman rats: age and sex variations relevance for modeling negative schizophrenia-like features

Social withdrawal is one of the most relevant negative symptoms of schizophrenia. Animal models that mimic schizophrenia's symptoms, in general, and negative symptoms, in particular, are difficult to develop because of the high complexity of symptoms and neurochemical disturbances that schizophrenia patients display throughout their lives. In recent years we have shown that Roman High- Avoidance (RHA) rats exhibit some phenotypes that are thought to represent positive symptoms, cognitive/attentional symptoms, as well as some negative symptoms of the disease. In the present study, we aimed at elucidating whether the social interaction (SI) deficits exhibited by adult male RHA rats, compared to their Roman Low-Avoidance (RLA) counterparts, are also present during adolescence, as well as whether there are between-strain differences in adolescent and adult female rats. The results of the present study show that adult male RHA rats exhibited a deficit in social preference compared to their RLA counterparts. Such a deficit was not observed in adolescent RHA rats or female rats of any age. The results also show that the adult male rats of both strains had significant decreases in social preference compared to the adolescent male rats. Additionally, we also show that female adult RHA rats have greater social preference than their male counterparts. These results seem to be in line with previous rodent and human studies and add face validity to the RHA rats as a model of schizophrenia.

Genome-wide Signatures of Early-Life Stress: Influence of Sex

Both history of early-life stress (ELS) and female sex are associated with increased risk for depression. The complexity of how ELS interacts with brain development and sex to impart risk for multifaceted neuropsychiatric disorders is also unlikely to be understood by examining changes in single genes. Here, we review an emerging literature on genome-wide transcriptional and epigenetic signatures of ELS and the potential moderating influence of sex. We discuss evidence both that there are latent sex differences revealed by ELS and that ELS itself produces latent transcriptomic changes revealed by adult stress. In instances where there are broad similarities in global signatures of ELS among females and males, genes that contribute to these patterns are largely distinct based on sex. As this area of investigation grows, an effort should be made to better understand the sex-specific impact of ELS within the human brain, specific contributions of chromosomal versus hormonal sex, how ELS alters the time course of normal transcriptional development, and the cell-type specificity of transcriptomic and epigenomic changes in the brain. A better understanding of how ELS interacts with sex to alter transcriptomic and epigenomic signatures in the brain will inform individualized therapeutic strategies to prevent or ameliorate depression and other psychiatric disorders in this vulnerable population.

Adolescent sleep health and school start times: Setting the research agenda for California and beyond: A research summit summary: A research summit summary

In fall 2019, California passed and signed into law SB328, the first US statewide legislation explicitly designed to protect adolescent sleep health by requiring most California public school districts to start no earlier than 8:00 AM for middle schools and 8:30 AM for high schools. Recognizing the unique opportunity presented by the bill's 3-year implementation period, a group of experts in adolescent sleep and school start times held a virtual summit on January 22-23, 2021 to (1) summarize the research on adolescent sleep and school start time change; (2) develop recommendations for relevant, refined, and innovative research areas and research questions; (3) provide input regarding research design, methodology, and implementation; and (4) offer a forum for networking, exchanging ideas, and establishing interdisciplinary research collaborations. Participants represented a multidisciplinary range of academic backgrounds including sleep and circadian biology, neuroscience, education, medicine, public health, mental health, safety, public policy, economics, implementation science, criminology, diversity studies, and science communication. This paper summarizes summit presentations regarding current knowledge on adolescent sleep health and school start times and key research recommendations from small group workshops on topics including research design and tools, methodological issues, sleep health disparities, logistical challenges in conducting school-based research, public-health impact, and novel and expanded approaches to research.

Acute Hypophagia and Changes in c-Fos Immunoreactivity in Adolescent Rats Treated with Low Doses of Oxytocin and Naltrexone

A recent case report has shown that an adjunctive oxytocin + naltrexone (OT + NTX) treatment promoted more robust hypophagia and body weight reduction than OT alone in an adolescent male with hypothalamic obesity after craniopharyngioma resection. Thus far, there has been no basic research in adolescent laboratory animals that would examine whether the benefit of OT + NTX on appetite extends onto adolescent individuals without surgically induced overeating. Thus, here we examined whether low doses of combined OT + NTX acutely affect post-deprivation intake of energy-dense, standard chow; intake of energy-dense and palatable high-fat high-sugar (HFHS) diet; or calorie-dilute, palaTable 10% sucrose solution without deprivation in adolescent male rats. We assessed whether OT + NTX decreases water intake after water deprivation or produces a conditioned taste aversion (CTA). Finally, by using c-Fos immunoreactivity, we determined changes in activity of feeding-related brain areas after OT + NTX. We found that individual subthreshold doses of OT and NTX decreased feeding induced by energy and by palatability. Significant c-Fos changes were noted in the arcuate and dorsomedial hypothalamic nuclei. The hypophagic doses of OT + NTX did not suppress water intake in thirsty rats and did not cause a CTA, which suggests that feeding reduction is not a secondary effect of gastrointestinal discomfort or changes in thirst processing. We conclude that OT + NTX is an effective drug combination to reduce appetite in adolescent male rats.

Cannabis Use and Emotional Intelligence in Adolescents during COVID-19 Confinement: A Social Network Analysis Approach

Confinement by COVID-19 had negative consequences on adolescent mental health, including increased cannabis use. Cannabis is related to variables that influence health and well-being. Emotional Intelligence is associated with adaptive coping styles, peer relationships, and social–emotional competencies. In adolescence, peer selection plays a unique role in the initiation of substance use. However, there are no studies during a confinement stage that analyse the relationships between networks, Emotional Intelligence, and cannabis use. The aim of this paper is to describe and analyse the consumption and friendship networks of an adolescent classroom and their relationship with Emotional Intelligence, cannabis use, and gender during COVID-19 confinement. Participants completed different questionnaires for Emotional Intelligence, cannabis use, and the consumption and friendship network. The sample consisted of 21 students from 10th grade, of which 47.6% were consumers. The friendship network correlates with the consumption network, and significant associations between emotional repair and being a cannabis user. The regression model points to the friendship network as a significant variable in predicting the classroom use network. This study highlights the role of the Social Network Analysis in predicting consumption networks during a COVID-19 confinement stage and serves as a tool for cannabis use prevention interventions in a specific population.

Long-term consequences of peri-adolescent social isolation on social preference, anxiety-like behaviour, and vasopressin neural circuitry of male and female rats

Social isolation during the juvenile and adolescent stages (peri-adolescent social isolation) can have long-term consequences for behavioural and neural development. Most of this research, however, has relied on data from males, and very few studies have included both sexes. The present study investigated the impact of peri-adolescent social isolation on social preference, anxiety-like behaviour, and vasopressin neural circuitry of male and female Long Evans rats. Rats were either housed alone for 3 weeks beginning at weaning (Isolated) or in groups (Group-housed). In adulthood, rats were tested in social preference, open field, marble burying, and light/dark box tests, and brains were processed for vasopressin immunohistochemistry. Isolated males exhibited a lower social preference score and spent more time in the light zone of the light/dark box than their group-housed counterparts. Isolated and Group-housed females did not differ in these measures. Peri-adolescent social isolation did not alter vasopressin fibre density in target areas known to influence social and anxiety-like behaviours (the lateral septum or lateral habenula), but increased fibre density in an output pathway of the circadian pacemaker (projections to the paraventricular nucleus of the thalamus); an effect detected across both sexes. A previously unreported sex difference was also detected for vasopressin fibre density in the paraventricular nucleus of the thalamus (females > males). These findings demonstrate long-term consequences of peri-adolescent social isolation on social preference, anxiety-like behaviour, and the circadian vasopressin pathway and suggest that socio-affective development of males is more vulnerable to social stressors during the juvenile and adolescent stages.

Mesocorticolimbic Dopamine Pathways Across Adolescence: Diversity in Development

Mesocorticolimbic dopamine circuity undergoes a protracted maturation during adolescent life. Stable adult levels of behavioral functioning in reward, motivational, and cognitive domains are established as these pathways are refined, however, their extended developmental window also leaves them vulnerable to perturbation by environmental factors. In this review, we highlight recent advances in understanding the mechanisms underlying dopamine pathway development in the adolescent brain, and how the environment influences these processes to establish or disrupt neurocircuit diversity. We further integrate these recent studies into the larger historical framework of anatomical and neurochemical changes occurring during adolescence in the mesocorticolimbic dopamine system. While dopamine neuron heterogeneity is increasingly appreciated at molecular, physiological, and anatomical levels, we suggest that a developmental facet may play a key role in establishing vulnerability or resilience to environmental stimuli and experience in distinct dopamine circuits, shifting the balance between healthy brain development and susceptibility to psychiatric disease.

Children's inhibitory control abilities in the presence of rewards are related to weight status and eating in the absence of hunger

The Reflective-Impulsive Dual Processes Model suggests that overeating occurs when the temptation to consume food overrides inhibitory control processes. However, how rewards interact with inhibitory control and their relation to children's weight status and food intake is not understood. Here, 7-to-11-year-old children (n = 66; 32 overweight/obese) completed two versions (baseline [i.e., non-reward incentivized/control] and reward incentivized [food, money, no reward]) of a Go/Nogo task. Intake of palatable foods in the absence of hunger (i.e., eating in the absence of hunger-EAH) was measured following a standardized meal. A drift diffusion model was used to characterize children's performance parameters on the Go/Nogo. On the baseline Go/Nogo, children with higher weight status responded more cautiously, but on reward trials for food/money children were more cautions and made more false alarms relative to the no reward condition. Energy intake during EAH positively correlated with FA errors for food and money vs. no reward, but sex moderated this effect such that FA positively associated with EAH in girls but not boys. Independent of sex, FA for money vs. no reward and food vs. money were both positively associated with energy consumed during EAH. These results suggest that the presence of food and money rewards impair inhibitory control processing, especially in children with higher weight status. Further, increased inhibitory control impairment in response to food rewards, specifically, may be a risk factor for disinhibited eating in girls. Though preliminary, results may be useful in the development of targeted treatments to help moderate excess consumption in children.

Modeling changes in probabilistic reinforcement learning during adolescence

In the real world, many relationships between events are uncertain and probabilistic. Uncertainty is also likely to be a more common feature of daily experience for youth because they have less experience to draw from than adults. Some studies suggest probabilistic learning may be inefficient in youths compared to adults, while others suggest it may be more efficient in youths in mid adolescence. Here we used a probabilistic reinforcement learning task to test how youth age 8-17 (N = 187) and adults age 18-30 (N = 110) learn about stable probabilistic contingencies. Performance increased with age through early-twenties, then stabilized. Using hierarchical Bayesian methods to fit computational reinforcement learning models, we show that all participants' performance was better explained by models in which negative outcomes had minimal to no impact on learning. The performance increase over age was driven by 1) an increase in learning rate (i.e. decrease in integration time scale); 2) a decrease in noisy/exploratory choices. In mid-adolescence age 13-15, salivary testosterone and learning rate were positively related. We discuss our findings in the context of other studies and hypotheses about adolescent brain development.

The temporal representation of experience in subjective mood

Humans refer to their mood state regularly in day-to-day as well as clinical interactions. Theoretical accounts suggest that when reporting on our mood we integrate over the history of our experiences; yet, the temporal structure of this integration remains unexamined. Here, we use a computational approach to quantitatively answer this question and show that early events exert a stronger influence on reported mood (a primacy weighting) compared to recent events. We show that a Primacy model accounts better for mood reports compared to a range of alternative temporal representations across random, consistent, or dynamic reward environments, different age groups, and in both healthy and depressed participants. Moreover, we find evidence for neural encoding of the Primacy, but not the Recency, model in frontal brain regions related to mood regulation. These findings hold implications for the timing of events in experimental or clinical settings and suggest new directions for individualized mood interventions.