Neural mechanisms of reward processing in preadolescent irritability: Insights from the ABCD study.

Elevated youth irritability is characterized by increased proneness to frustration relative to peers when rewards are blocked, and is a transdiagnostic symptom that predicts multiple forms of psychopathology and poorer socioeconomic outcomes in adulthood. Although mechanistic models propose that irritability is the result of aberrant reward-related brain function, youth irritability as it relates to multiple components of reward processes, including reward anticipation, gain, and loss, has yet to be examined in large, population-based samples. Data from the Adolescent Brain and Cognitive Development (ABCD) baseline sample (N = 5923) was used to examine associations between youth irritability (measured by parent-report) and reward-related brain activation and connectivity in a large, preadolescent sample. Preadolescents (M age = 9.96 years, SD = 0.63) performed the Monetary Incentive Delay task during functional MRI acquisition. In the task, during the anticipation period, participants were informed of the upcoming trial type (win money, lose money, no money at stake) and waited to hit a target; during the feedback period, participants were informed of their success. Whole brain and region of interest (ROI) analyses evaluated task conditions in relation to irritability level. Preadolescents with higher compared to lower levels of irritability demonstrated blunted prefrontal cortex activation in the anticipation period and exaggerated striatum-prefrontal connectivity differences among reward conditions during the feedback period. These effects persisted after adjusting for co-occurring anxiety, depression, and attention-deficit/hyperactivity disorder symptoms. These findings provide evidence for the role of reward salience in pathophysiological models of youth irritability, suggesting a mechanism that may contribute to exaggerated behavioral responses.

Dimensions of experienced gender and prospective self-injurious thoughts and behaviors in preadolescent children: A national study.

OBJECTIVES: Gender diverse youth face higher risk of engaging in self-injurious thoughts and behaviors (SITBs) compared to cisgender youth. Limitations in past research include a focus on older adolescents, an emphasis on specific gender identity labels that may not be inclusive of the range of youth gender experiences, and reliance on cross-sectional data. Thus, the current study prospectively evaluated dimensions of experienced gender in relation to first-onset SITBs among preadolescents. METHODS: Data were drawn from the Adolescent Brain Cognitive Development Study, a longitudinal study of youth across the United States. Youth (n = 7909) were aged 10-11 during initial assessment, and follow-up was conducted one year later. Two dimensions of experienced gender, felt-gender incongruence (not feeling aligned with the gender associated with one's sex assigned at birth) and gender non-contentedness (feeling dissatisfaction with the gender associated with one's sex assigned at birth), were assessed. Primary outcomes included non-suicidal self-injury (NSSI), suicidal ideation (SI), and suicide attempts (SA). RESULTS: Logistic regressions were conducted stratified by sex assigned at birth. For youth assigned female at birth, felt-gender incongruence was prospectively associated with first-onset NSSI and SI and gender non-contentedness was prospectively associated with first-onset of NSSI. For youth assigned male at birth, gender non-contentedness was prospectively associated with first-onset SI. Diverse experienced gender did not prospectively predict SA. CONCLUSIONS: Dimensions of experienced gender may be associated with subsequent first-onset SITBs among preadolescents. These findings support the need for future research on risk and protective factors that may mediate or moderate this relationship.

Longitudinal associations between deviant peer affiliation and externalizing behavior in Chinese preadolescence: Differentiating between-person effects from within-person effects.

The present study employed the cross-lagged panel model and the random intercepts cross-lagged panel model to investigate the longitudinal association between deviant peer affiliation and externalizing behavior in Chinese preadolescents. A sample of 1987 students, comprising 56.10% male participants with a mean age of 12.32 years (SD = 0.53), from Guangdong and Shandong provinces, completed the Deviant Peer Affiliation Scale and the Externalizing Behavior Scale in biannual surveys. The surveys were conducted in the autumn semester of 7th grade, the spring semester of 7th grade, and the autumn semester of 8th grade. The cross-lagged panel model illustrated a bidirectional association between adolescents' involvement with deviant peers and externalizing behavior. Conversely, the random intercepts cross-lagged panel model indicated a positive association between deviant peer affiliation and externalizing behavior at the between-person level. At the within-person level, a significant predictive correlation was identified between the association with deviant peers and subsequent externalizing behavior, whereas the reverse pathway was determined to be statistically insignificant. To comprehend the connection between deviant peer association and externalizing behavior in preadolescence, it is essential to differentiate between between-person and within-person effects and utilize a sophisticated research methodology.

Behavioural Problems in Preadolescence: Does Nutritional Status Have a Role?

INTRODUCTION: Malnutrition in children and adolescents is a global issue particularly in low- and middle-income countries, while behavioural problems are becoming a growing public health concern in the area of child and adolescent mental health, with very few studies examining their association in preadolescence. This study aimed to assess the epidemiological relationship between malnutrition and behavioural problems in preadolescence. METHODS: A school based, cross-sectional survey was conducted in Karachi, Pakistan. Total 660, 11- to 12-year-old preadolescents were selected from a middle-class, coeducational school chain. Sociodemographic questionnaires and an officially adapted version of Youth Self-Report Form (YSR), which is the child and adolescent reported version of the Child Behavior Checklist (CBCL), were used to collect data, along with anthropometric assessments following the WHO protocol. RESULTS: Thin and stunted preadolescents had significantly higher odds of internalizing problems (AOR = 2.05, p = 0.003 and AOR = 2.09, p = 0.039, respectively) than normal ones. Overnutrition was not associated with any behavioural issues. According to the Composite Index of Anthropometric Failure, 40% of preadolescents had at least one type of malnutrition and among them about 3% had co-occurring malnutrition (stunted and thin or overweight). They significantly had higher risk of being associated with the internalizing problems (AOR 2.92, p = 0.027). The effect was considerably higher than that associated with stunted or thin only, highlighting the cumulative impact of the co-occurring malnutrition on the internalizing problems. CONCLUSION: Our study concludes that overnutrition and undernutrition are prevalent in preadolescents, with significant association of undernutrition with internalizing problems. Moreover, our study is the first that reports that the co-occurrence of malnutrition is significantly associated with increased risk of internalizing problems. This study highlights the importance of the link between physical and mental health and emphasizes the need for holistic interventions and programmes for addressing preadolescents' issues.

Neural mechanisms of inhibitory control in preadolescent irritability: Insights from the ABCD study.

OBJECTIVE: Elevated pediatric irritability is a transdiagnostic symptom that predicts multiple mental health problems in adolescence and adulthood. Altered top-down regulatory networks, such as inhibitory control networks that suppress an impulse in favor of goal-directed behavior, are thought to contribute to high levels of youth irritability. Nevertheless, little work has examined links between youth irritability and neural processes supporting inhibitory control in large diverse samples, nor have they focused on the key period ramping up to adolescence (i.e., preadolescence). METHOD: Functional MRI data from 5380 preadolescents (age M=9.97 years, SD=0.62) in the baseline Adolescent Brain and Cognitive Development (ABCD) Study were analyzed. Parents reported on their preadolescent's irritability. The stop signal task (SST) was leveraged to probe successful and failed inhibitory control. Activation and functional connectivity with amygdala, ventral striatum, and prefrontal seed regions were calculated during the SST and used in whole brain and region of interest (ROI) group-level analyses evaluating irritability effects. RESULTS: Preadolescents with higher levels of irritability displayed decreases in functional connectivity among amygdala, ventral striatum, and prefrontal cortex regions during both successful and failed inhibitory control conditions. These results remained after adjusting for co-occurring anxiety, depression, and attention-deficit/hyperactivity symptoms. CONCLUSIONS: Findings suggest neural aberrations in inhibitory control play a role in the pathophysiology of preadolescent irritability and associations are not merely due to co-occurring symptoms. Neural mechanisms of inhibitory control associated with irritability may provide novel intervention targets.

Fetal femur length and risk of diabetes in adolescence: a prospective cohort study.

BACKGROUND: Diabetes is more apparent in adulthood but may be dormant in childhood and originates during early fetal development. In fetal biometry, femur length (FL) is crucial for assessing fetal growth and development. This study aimed to assess potential associations between fetal femur growth and prediabetic biomarkers in Bangladeshi children. METHODS: A cohort study embedded in a population-based maternal food and micronutrient supplementation (MINIMat) trial was conducted in Matlab, Bangladesh. The children in the cohort were followed up until 15 years of age. In the original trial, pregnancy was confirmed by ultrasound before 13 gestational weeks (GWs). Afterward, ultrasound assessments were performed at 14, 19, and 30 GWs. FL was measured from one end to the other, capturing a complete femoral image. The FL was standardized by GW, and a z-score was calculated. FBG and HbA1c levels were determined in plasma and whole blood, and the triglyceride-glucose index, a biomarker of insulin resistance, was calculated as Ln [fasting triglycerides (mg/dl) × fasting glucose (mg/dl)/2]. Multivariable linear regression analysis using a generalized linear model was performed to estimate the effects of FL at 14, 19 and 30 GWs on prediabetic biomarkers at 9 and 15 years of age. Maternal micronutrient and food supplementation group, parity, child sex, and BMI at 9 years or 15 years were included as covariates. RESULTS: A total of 1.2% (6/515) of the participants had impaired fasting glucose during preadolescence, which increased to 3.5% (15/433) during adolescence. At 9 years, 6.3% (32/508) of the participants had elevated HbA1c%, which increased to 28% (120/431) at 15 years. Additionally, the TyG index increased from 9.5% (49/515) (during preadolescence) to 13% (56/433) (during adolescence). A one standard deviation decrease in FL at 14 and 19 GWs was associated with increased FBG (ß = - 0.44 [- 0.88, - 0.004], P = 0.048; ß = - 0.59 [- 1.12, - 0.05], P = 0.031) and HbA1c (ß = - 0.01; [- 0.03, -0.005], P = 0.007; ß = - 0.01 [- 0.03, - 0.003], P = 0.018) levels at 15 years. FL was not associated with diabetic biomarkers at 9 years. CONCLUSION: Mid-trimester impaired femur growth may be associated with elevated prediabetic biomarkers in Bangladeshi adolescents.

Reward positivity moderates the association between pubertal status and social anxiety symptoms in nine-to-12-year-old youths.

The transition to adolescence is characterized by rapid development of puberty, reward processing, and internalizing psychopathology (i.e., depression and anxiety). More advanced pubertal status and altered reward processing are both known to be associated with elevated internalizing symptoms. However, it was unclear to what extent pubertal status and reward processing interacted with each other in predicting internalizing psychopathology. We examined how the puberty-psychopathology association was moderated by the reward processing indexed by ERPs, including the reward positivity (RewP) and the late positive potential (LPP). A-hundred-and-fifteen nine-to-12-year-old typically developing youths (66 girls; Mean age/SD =10.98/1.18 years) reported their pubertal status and symptoms of depression and social anxiety and completed an EEG Doors task that assessed monetary reward feedback processing. A principal component analysis of the ERP data identified a RewP, an anterior LPP, and a posterior LPP, elicited by the win and loss feedback of the task. The puberty-social anxiety relationship was moderated by the RewP, an identified neural marker of reward sensitivity. Specifically, more advanced puberty was associated with heightened social anxiety symptoms in the presence of a larger, but not smaller, RewP. We did not observe any moderating effect of the LPPs. Our study provided novel evidence that a hypersensitivity toward the reward stimuli (indexed by an enlarged RewP) further exacerbated the risks associated with more advanced pubertal status for social anxiety.

Associations between Positive Childhood Experiences (PCEs), Discrimination, and Internalizing/Externalizing in Pre-Adolescents.

OBJECTIVE: This study aimed to investigate the relationships between four types of perceived discrimination (based on race and ethnicity, nationality/country of origin, gender identity, weight/body size), individually and cumulatively; positive childhood experiences (PCEs); and behavioral symptoms among pre-adolescent youth. METHODS: This study was a secondary analysis of data from the Adolescent Brain Cognitive Development (ABCD) Study, a US-based cohort study of pre-adolescent youth in the United States (N = 10,915). Our outcome was emotional/behavioral symptoms measured by the Child Behavior Checklist. Primary exposures were four types of discrimination, a count of 0-5 PCEs, and other adverse childhood experiences (ACEs). Multiple logistic regression models were used to estimate the relationship between perceived discrimination and clinical-range behavioral symptoms, including the role of PCEs and ACEs. RESULTS: Weight discrimination was the most frequent exposure (n = 643, 5.9%). Race and weight perceived discrimination were associated with clinical-range externalizing and internalizing symptoms, respectively, but these associations were non significant once other ACEs were added to models. Cumulative discrimination was associated with clinical-range Child Behavior Checklist (CBCL) scores, even when accounting for other ACEs (aOR=1.47, 95% CI=1.2-1.8). PCEs slightly reduced the strength of this relationship and were independently associated with reduced symptoms (aOR=0.82, 95% CI=0.72-0.93). CONCLUSIONS: Results of this national study suggest cumulative discrimination can exert emotional/behavioral health harm among youth. PCEs were independently associated with reduced behavioral symptoms. There is a need for further research on how to prevent discrimination and bolster PCEs by targeting upstream social inequities in communities.

"A 'Cool' Kid Wears a Brand, and Everyone's following Him" Hierarchal Social Status in Preadolescence: A New Developmental Perspective.

Inequality in hierarchical social status, especially among socially excluded children, profoundly affects preadolescents. Historically viewed through a lens of psychopathology and moral deficiencies, it challenges the education system's approaches and interventions. This article introduces a developmental perspective, highlighting the hierarchical social status' role in shaping classroom cohesion, strength, and distinctiveness. This study's phenomenological, qualitative methodology aimed to gain preliminary insight into the children's perspectives. Drawing from 12 focus group discussions involving 140 latency-age (grade 5) children in Israel, it uniquely reveals the dynamic nature of hierarchical social status influenced by children's connections with the group. This dynamism promotes group unity, strengthens bonds, and prioritizes collective concerns, contributing to the development of a "social self" in the latency phase. Beyond theory, this study proposes innovative interventions to address social status disparities.

Spatiotemporal EEG dynamics of the sleep onset process in preadolescence.

BACKGROUND: During preadolescence the sleep electroencephalography undergoes massive qualitative and quantitative modifications. Despite these relevant age-related peculiarities, the specific EEG pattern of the wake-sleep transition in preadolescence has not been exhaustively described. METHODS: The aim of the present study is to characterize regional and temporal electrophysiological features of the sleep onset (SO) process in a group of 23 preadolescents (9-14 years) and to compare the topographical pattern of slow wave activity and delta/beta ratio of preadolescents with the EEG pattern of young adults. RESULTS: Results showed in preadolescence the same dynamics known for adults, but with peculiarities in the delta and beta activity, likely associated with developmental cerebral modifications: the delta power showed a widespread increase during the SO with central maxima, and the lower bins of the beta activity showed a power increase after SO. Compared to adults, preadolescents during the SO exhibited higher delta power only in the slowest bins of the band: before SO slow delta activity was higher in prefrontal, frontal and occipital areas in preadolescents, and, after SO the younger group had higher slow delta activity in occipital areas. In preadolescents delta/beta ratio was higher in more posterior areas both before and after the wake-sleep transition and, after SO, preadolescents showed also a lower delta/beta ratio in frontal areas, compared to adults. CONCLUSION: Results point to a general higher homeostatic drive for the developing areas, consistently with plastic-related maturational modifications, that physiologically occur during preadolescence.

Associations between Fluid Intelligence and Physical Fitness in School Children.

Previous research has highlighted that active lifestyles that contribute to improved physical fitness are positively related to cognitive functioning in children and adolescents. Specifically, the increase in physical condition at school age is considered relevant because it is related to better cognitive ability and greater academic performance. Thus, the aim of this study was to analyze the relationships between explosive strength, speed-agility, and fluid reasoning in schoolchildren. To achieve this objective, an associative, comparative, and predictive design was used in this research. A total of 129 children participated in this study (age: M = 9.48; SD = 0.99). To assess fluid reasoning, the Raven test's Standard Progressive Matrices Subtest and the Wechsler Intelligence Scale for Children (WISC-V) were used. To assess physical fitness, the speed-agility test and the horizontal jump test (ALPHA-fitness battery tests), as well as the ball throw test (2 kg), were used. The results showed that the speed-agility test significantly predicted WISC-V Fluid Reasoning Index scores, and the medicine ball toss test significantly predicted Raven test scores. The results obtained highlight the associations between physical condition at these ages and fluid intelligence. This suggests that promoting active lifestyles that improve physical fitness could have a positive impact on children's cognitive health.

The Role of SES in Preadolescence: Understandings and Group Evaluations based on Income, Education, and Occupation.

Socioeconomic status (SES) predicts many facets of preadolescents' life opportunities, yet little is known about how children perceive SES and whether it plays a role in their group evaluations. This study examined preadolescents' socioeconomic understandings and biases (investigated presenting fictitious peers varying in SES), while separating the three SES-indicators income, education and occupation. Five classes (Grade 4-6) with 89 students (Mage = 10.44, SD = 0.93; 40% female) participated. Overall, preadolescents understood that the SES indicators income, education and occupation are related to each other. At the same time, they differentiated between the indicators in their group evaluations; they showed a positive bias for peers with high-educated parents, whereas for occupation and income there was no clear overall bias. This shows that differences between SES indicators are meaningful for children, which emphasizes the importance to distinguish between specific SES-indicators when studying the role of SES for preadolescents' social life.

Family Resilience and Children's Subjective Well-Being: A Two-Wave Study.

According to the Theory of Change, the resilience of the family unit plays a crucial role in shaping the developmental trajectory of children. Families exhibiting higher levels of family resilience are typically characterized by transparent and effective communication, optimistic outlooks on adversity, adept problem-solving skills, strong spiritual beliefs, and effective management of social and financial resources. While existing research has indicated that parental and familial characteristics can predict diverse outcomes for children, investigations concerning the association between family resilience and children's subjective well-being remains limited. Therefore, this study aims to examine whether different dimensions of family resilience can predict changes in children's subjective well-being, tested one year later. The sample includes 762 child-mother-father triads (intact families). Children aged 9-13 years (48% boys, age = 11.04, SD = 1.16) assessed their life satisfaction, positive and negative affect in two study waves, while mothers and fathers assessed family resilience in the first wave. A dyadic data common fate model was employed to create latent variables representing family resilience. Three latent variables were: family problem-solving, family spirituality, and utilization of social and economic resources. Findings from the structural equation model indicated a positive association between higher levels of family problem-solving and increased children's life satisfaction, alongside a negative relationship between higher family spirituality and negative affect. Parental assessments of social and economic resources utilization were not uniquely related to children's life satisfaction, positive, or negative affect.

Joint kinematics and SPM analysis of gait in children with and without Down syndrome.

BACKGROUND: Individuals with Down syndrome (DS) walk with altered gait patterns compared to their typically developing (TD) peers. While walking at faster speeds and with external ankle load, preadolescents with DS demonstrate spatiotemporal and kinetic improvements. However, evidence of joint kinematic adjustments is unknown, which is imperative for targeted rehabilitation design. RESEARCH QUESTION: How does increasing walking speed and adding ankle load affect the joint kinematics of children with and without DS during overground walking? METHODS: In this cross-sectional observational study, thirteen children with DS aged 7-11 years and thirteen age- and sex-matched TD children completed overground walking trials. There were two speed conditions: normal speed and fast speed (as fast as possible without running). There were two load conditions: no load and ankle load (2% of body mass added bilaterally above the ankle). A motion capture system was used to register the ankle, knee, and hip joint angles in the sagittal plane. Peak flexion/extension angles, range of motion, and timing of peak angles were identified. In addition, statistical parametric mapping (SPM) was conducted to evaluate the trajectory of the ankle, knee, and hip joint angles across the entire gait cycle. RESULTS AND SIGNIFICANCE: SPM analysis revealed the DS group walked with greater ankle, knee, and hip flexion compared to the TD group for most of the gait cycle, regardless of condition. Further, increasing walking speed led to improved ankle joint kinematics in both groups by shifting peak plantarflexion closer to toe-off. However, knee extension during stance was challenged in the DS group. Adding ankle load improved hip and knee kinematics in both groups but reduced peak plantarflexion around toe-off. The kinematic adjustments in the DS group suggest specific motor strategies to accommodate their neuromuscular deficits, which can provide a foundation to design targeted gait-based interventions for children with DS.

Associations between disordered eating, internalizing symptoms, and behavioral and neural correlates of response inhibition in preadolescence.

Response inhibition difficulties are reported in individuals with eating disorders (EDs), anxiety, and depression. Although ED symptoms and internalizing symptoms co-occur in preadolescence, there is limited research examining associations between these symptoms and response inhibition in this age group. This study is the first to investigate the associations between behavioral and neural markers of response inhibition, disordered eating (DE), and internalizing symptoms in a community sample of preadolescents. Forty-eight children (M age = 10.95 years, 56.3% male) completed a Go/NoGo task, whereas electroencephalography was recorded. Self-report measures of DE and internalizing symptoms were collected. Higher levels of anxiety and depression were associated with neural markers of suboptimal response inhibition (attenuated P3NoGo amplitudes) in preadolescence. In contrast, higher levels of depression were associated with greater response inhibition at a behavioral level. These findings suggest internalizing symptoms in preadolescence are associated with P3-indexed difficulties in evaluation and monitoring, but these are not sufficient to disrupt behavioral performance on a response inhibition task. This pattern may reflect engagement of compensatory processes to support task performance. DE was not significantly associated with response inhibition, suggesting that difficulties in response inhibition may only be reliably observed in more chronic and severe DE and ED presentations.

A Longitudinal Study of the Development of Executive Function and Calibration Accuracy.

This longitudinal study examined the development of executive function and calibration accuracy in preadolescents. This study's sample consisted of 262 students (127 females) from grades 4 (n = 91), 5 (n = 89), and 6 (n = 82) who took measures of executive function and performance calibration in a sport task three times over 20 months. A latent growth-curve modeling analysis showed a significant relationship between the rates of change of executive function and calibration accuracy. The results also showed a dynamic interplay in the development of executive function and calibration accuracy. There were significant interindividual differences in the estimated population means both in executive function and calibration accuracy and in the rate of change of executive function, but not in the rate of change of calibration accuracy. The age of the participants had a positive effect only on the estimated population mean of executive function.

Comparing two measures of neighborhood quality and internalizing and externalizing behaviors in the adolescent brain cognitive development study.

PURPOSE: There is widespread recognition of the importance and complexity of measuring neighborhood contexts within research on child psychopathology. In this study, we assessed the cross-sectional associations between two measures of neighborhood quality and internalizing and externalizing behaviors in preadolescence. METHODS: Drawing on baseline data from the Adolescent Brain Cognitive Development Study (n = 10,577 preadolescents), we examined two multi-component assessments of neighborhood quality in relation to children's internalizing and externalizing symptoms: the Area Deprivation Index (ADI), which measures socioeconomic adversity, and the Child Opportunity Index 2.0 (COI), which measures economic, educational, and environmental opportunity. Both measures were categorized into quintiles. We then used mixed-effects linear regression models to examine bivariate and adjusted associations. RESULTS: The bivariate associations displayed strong inverse associations between the COI and ADI and externalizing symptoms, with a graded pattern of fewer externalizing behaviors with increasing neighborhood quality. Only the ADI was associated with externalizing behaviors in models adjusted for child and family characteristics. We did not observe a clear association between either measure of neighborhood quality and internalizing behaviors in bivariate or adjusted models. CONCLUSIONS: Neighborhood quality, as measured by the COI and ADI, was associated with externalizing behaviors in preadolescent children. The association using the ADI persisted after adjustment for family-level characteristics, including financial strain. Our results indicate that different assessments of neighborhood quality display distinct associations with preadolescent behavioral health. Future research is needed to assess the association between neighborhood quality and behavior trajectories and to identify place-based intervention strategies.

Pre-adolescence repeat exposure to sub-anesthetic doses of ketamine induces long-lasting behaviors and cognition impairment in male and female rat adults.

In pre-adolescence, repeated anesthesia may be required for therapeutic interventions. Adult cognitive and neurobehavioral problems may result from preadolescent exposure to anesthetics. This study examined the long-term morphological and functional effects of repeated sub-anesthetic doses of ketamine exposure on male and female rat adults during pre-adolescence. Weaned 48 pre-adolescent rats from eight mothers and were randomly divided into four equal groups: control group and the ketamine group of males and females (20 mg/kg daily for 14 days); then animals received care for 20-30 days. Repeated exposure to sub-anesthetic doses of ketamine on cognitive functions was assayed using Social discrimination and novel object tests. Besides, an elevated plus maze and fear conditioning apparatus were utilized to determine exploratory and anxiety-like behavior in adults. Toluidine blue stain was used to evaluate the number of dead neurons in the hippocampus, and the effects of ketamine on synaptic plasticity were compared in the perforant pathway of the CA1 of the hippocampus. Our study indicates that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can result in neurobehavioral impairment in male and female rat adulthood but does not affect anxiety-like behavior. We found a significant quantifiable increase in dark neurons. Recorded electrophysiologically, repeat sub-anesthetic doses of ketamine resulted in hampering long-term potentiation and pair pulse in male adult animals. Our results showed that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can induce hippocampus and neuroplasticity changes later in adulthood. This study opens up a new line of inquiry into potential adverse outcomes of repeated anesthesia exposure in pre-adolescent rats.

Trial-level ERPs predicted behavioral responses during self-referential processing in late childhood.

Self-referential information is uniquely salient and preferentially processed even in children. The literature has used the self-referent encoding task (SRET) combined with event-related potentials (ERPs) to study self-referential processing and its associations with youth psychopathology. However, it is unclear how the ERP and behavioral indices of SRET are associated with each other, although this knowledge can promote our mechanistic understanding of this construct and its role in psychopathology. We examined this question in 115 9- to 12-year-old children, a critical period for the development of self-related concepts. By applying a multilevel modeling approach to the trial-level data of SRET, we disaggregated the between- and within-person variability and observed within-person, but not between-person, effects of the P2 and late positive potential (LPP) on behavioral responses: a larger P2 on a given trial predicted a faster response in this trial; a larger LPP on a given trial predicted a higher likelihood of endorsing the word of this trial. We provided novel evidence on how the within-person variability of the ERPs predicted the overt responses of the SRET in children. These findings inform our mechanistic knowledge of self-referential processing and shed light on a better understanding of the role of self-referential processing in the development of psychopathology.

Non-specific and ski-specific performance development in peri-pubertal cross-country skiers.

PURPOSE: To evaluate non-specific and ski-specific performance development in male (M) and female (F) peri-pubertal cross-country skiers and to evaluate their relationship with cross-country skiing (XCS) performance and biological maturation within each age category and sex. METHODS: Twenty-one and 19 athletes under 14 and 16 years old, respectively (U14 and U16), were tested for biological maturation; non-specific speed, agility, strength, endurance, and balance; ski-specific speed, agility, and endurance. XCS index was considered as average percentage time-gap from the winner in four official races. Sex and age-category effects were verified and a model predicting XCS index was extrapolated for each group. RESULTS: Performance capacities raised across age categories (p < 0.05) except for non-specific speed, agility, balance, and relative arm strength (p > 0.05). F showed advanced biological maturation and greater balance than M (p < 0.05), while M showed higher performance capacities (p < 0.05). XCS index was not related to biological maturation within each group (p > 0.05); its variance was explained by non-specific speed and ski-specific upper-body endurance in M-U14 (p = 0.014), lower-limb strength and ski-specific agility in M-U16 and F-U14 (both p = 0.001), ski-specific upper-body endurance in F-U16 (p = 0.002). CONCLUSION: Ski-specific performance capacities still develop during peri-puberty, with peri-pubertal M overperforming with respect to F of comparable performance level. XCS index was not influenced by biological maturation withing each age category, but it was rather explained by specific parameters that commonly undergo the "adolescent spurts", accordingly to the average biological maturation level of M and F athletes of each age category.