Healthy and abnormal development of the prefrontal cortex

Episodic memory development: Bridging animal and human research

Human episodic memory is not functionally evident until about 2 years of age and continues to develop into the school years. Behavioral studies have elucidated this developmental timeline and its constituent processes. In tandem, lesion and neurophysiological studies in non-human primates and rodents have identified key neural substrates and circuit mechanisms that may underlie episodic memory development. Despite this progress, collaborative efforts between psychologists and neuroscientists remain limited, hindering progress. Here, we seek to bridge human and non-human episodic memory development research by offering a comparative review of studies using humans, non-human primates, and rodents. We highlight critical theoretical and methodological issues that limit cross-fertilization and propose a common research framework, adaptable to different species, that may facilitate cross-species research endeavors.

Major Depressive Disorder as a Driver of Dual Systems Model Development During Adolescence and Emerging Adulthood Among Justice-Involved Youth: Is Salience Age-Graded?

The dual systems model is a psychological framework centered on differential development of sensation-seeking and impulse control during adolescence and emerging adulthood with implications for understanding antisocial behavior. However, there is a dearth of research which has examined mental illness as a driver of differential development of these constructs. This study examined major depressive disorder as a risk factor for elevated sensation-seeking and diminished impulse control and tested to determine whether the salience differed by age. The Pathways to Desistance data were analyzed. Mixed effects models examined the direct effect of major depressive disorder on dual systems outcomes and test for moderation by age. Findings indicated that major depressive disorder at baseline was associated with increased sensation-seeking and diminished impulse control. Relationships did not differ in salience based on age. Results suggest that treatment effective for addressing depression may have relevance for mitigating the impact of the disorder on cognition.

Reorganization of adolescent prefrontal cortex circuitry is required for mouse cognitive maturation

Most cognitive functions involving the prefrontal cortex emerge during late development. Increasing evidence links this delayed maturation to the protracted timeline of prefrontal development, which likely does not reach full maturity before the end of adolescence. However, the underlying mechanisms that drive the emergence and fine-tuning of cognitive abilities during adolescence, caused by circuit wiring, are still unknown. Here, we continuously monitored prefrontal activity throughout the postnatal development of mice and showed that an initial activity increase was interrupted by an extensive microglia-mediated breakdown of activity, followed by the rewiring of circuit elements to achieve adult-like patterns and synchrony. Interfering with these processes during adolescence, but not adulthood, led to a long-lasting microglia-induced disruption of prefrontal activity and neuronal morphology and decreased cognitive abilities. These results identified a nonlinear reorganization of prefrontal circuits during adolescence and revealed its importance for adult network function and cognitive processing.

Understanding the Impact of Deviant Peer Association on Dual Systems Model Development: Testing the Moderating Role of ADHD

ABSTRACT

Recent research has indicated that deviant peers may play a role in cognitive development. This is particularly the case for the dual systems model, a key framework for understanding engagement in antisocial behavior during adolescence and emerging adulthood. However, limited research has examined how preexisting mental health concerns may moderate these relationships. This study used the Pathways to Desistance data to examine attention deficit hyperactivity disorder (ADHD) as a moderator of the relationships between deviant peer association and dual systems model constructs. Generalized estimating equations were used to test these relationships. Results indicated that deviant peer association and the presence of ADHD both predicted increased sensation-seeking and lower impulse control. ADHD significantly moderated the relationship between deviant peer association and impulse control, indicating a weaker impact of deviant peer association on impulse control among participants with ADHD. No significant interaction was observed for the relationship between deviant peer association and sensation-seeking.

Progressive Voxel-Wise Homotopic Connectivity from childhood to adulthood: Age-related functional asymmetry in resting-state functional magnetic resonance imaging

Homotopic connectivity during resting state has been proposed as a risk marker for neurologic and psychiatric conditions, but a precise characterization of its trajectory through development is currently lacking. Voxel-Mirrored Homotopic Connectivity (VMHC) was evaluated in a sample of 85 neurotypical individuals aged 7-18 years. VMHC associations with age, handedness, sex, and motion were explored at the voxel-wise level. VMHC correlates were also explored within 14 functional networks. Primary and secondary outcomes were repeated in a sample of 107 adults aged 21-50 years. In adults, VMHC was negatively correlated with age only in the posterior insula (false discovery rate p < .05, >30-voxel clusters), while a distributed effect among the medial axis was observed in minors. Four out of 14 considered networks showed significant negative correlations between VMHC and age in minors (basal ganglia r = -.280, p = .010; anterior salience r = -.245, p = .024; language r = -.222, p = .041; primary visual r = -.257, p = .017), but not adults. In minors, a positive effect of motion on VMHC was observed only in the putamen. Sex did not significantly influence age effects on VMHC. The current study showed a specific decrease in VMHC for minors as a function of age, but not adults, supporting the notion that interhemispheric interactions can shape late neurodevelopment.

Sensory Inhibition and Speech Perception-in-Noise Performance in Children With Normal Hearing

PURPOSE

This study investigated whether sensory inhibition in children may be associated with speech perception-in-noise performance. Additionally, gating networks associated with sensory inhibition were identified via standardized low-resolution brain electromagnetic tomography (sLORETA), and the detectability of the cortical auditory evoked potential (CAEP) N1 response was enhanced using a 4- to 30-Hz bandpass filter.

METHOD

CAEP gating responses, reflective of inhibition, were evoked via click pairs and recorded using high-density electroencephalography in neurotypical 5- to 8-year-olds and 22- to 24-year-olds. Amplitude gating indices were calculated and correlated with speech perception in noise. Gating generators were estimated using sLORETA. A 4- to 30-Hz filter was applied to detect the N1 gating component.

RESULTS

Preliminary findings indicate children showed reduced gating, but there was a correlational trend between better speech perception and decreased N2 gating. Commensurate with decreased gating, children presented with incomplete compensatory gating networks. The 4- to 30-Hz filter identified the N1 response in a subset of children.

CONCLUSIONS

There was a tenuous relationship between children's speech perception and sensory inhibition. This may suggest that sensory inhibition is only implicated in atypically poor speech perception. Finally, the 4- to 30-Hz filter settings are critical in N1 detectability.

SIGNIFICANCE

Gating may help evaluate reduced sensory inhibition in children with clinically poor speech perception using the appropriate methodology. Cortical gating generators in typically developing children are also newly identified.

Altered development of structural MRI connectome hubs at near-term age in very and moderately preterm infants

Preterm infants may exhibit altered developmental patterns of the brain structural network by endogenous and exogenous stimuli, which are quantifiable through hub and modular network topologies that develop in the third trimester. Although preterm brain networks can compensate for white matter microstructural abnormalities of core connections, less is known about how the network developmental characteristics of preterm infants differ from those of full-term infants. We identified 13 hubs and 4 modules and revealed subtle differences in edgewise connectivity and local network properties between 134 preterm and 76 full-term infants, identifying specific developmental patterns of the brain structural network in preterm infants. The modules of preterm infants showed an imbalanced composition. The edgewise connectivity in preterm infants showed significantly decreased long- and short-range connections and local network properties in the dorsal superior frontal gyrus. In contrast, the fusiform gyrus and several nonhub regions showed significantly increased wiring of short-range connections and local network properties. Our results suggested that decreased local network in the frontal lobe and excessive development in the occipital lobe may contribute to the understanding of brain developmental deviances in preterm infants.

Changes in and asymmetry of the proteome in the human fetal frontal lobe during early development

Inherent hemispheric asymmetry is important for cognition, language and other functions. Describing normal brain and asymmetry development during early development will improve our understanding of how different hemispheres prioritize specific functions, which is currently unknown. Here, we analysed developmental changes in and asymmetry of the proteome in the bilateral frontal lobes of three foetal specimens in the late first trimester of pregnancy. We found that during this period, the difference in expression between gestational weeks (GWs) increased, and the difference in asymmetric expression decreased. Changes in the patterns of protein expression differed in the bilateral frontal lobes. Our results show that brain asymmetry can be observed in early development. These findings can guide researchers in further investigations of the mechanisms of brain asymmetry. We propose that both sides of the brain should be analysed separately in future multiomics and human brain mapping studies.

Proteomic analysis of human early fetal brain tissue is undertaken to investigate bilateral developmental changes of protein expression and left-right asymmetries of protein expression.

The influence of peripheral emotions on inhibitory control among children

In this study, we investigated the cognitive-emotional interplay by measuring the effects of executive competition (Pessoa, 2013), i.e., how inhibitory control is influenced when emotional information is encountered. Sixty-three children (8 to 9 years of age) participated in an inhibition task (central task) accompanied by happy, sad, or neutral emoticons (displayed in the periphery). Typical interference effects were found in the main task for speed and accuracy, but in general, these effects were not additionally modulated by the peripheral emoticons indicating that processing of the main task exhausted the limited capacity such that interference from the task-irrelevant, peripheral information did not show (Pessoa, 2013). Further analyses revealed that the magnitude of interference effects depended on the order of congruency conditions: when incongruent conditions preceded congruent ones, there was greater interference. This effect was smaller in sad conditions, and particularly so at the beginning of the experiment. These findings suggest that the bottom-up perception of task-irrelevant emotional information influenced the top-down process of inhibitory control among children in the sad condition when processing demands were particularly high. We discuss if the salience and valence of the emotional stimuli as well as task demands are the decisive characteristics that modulate the strength of this relation.

Assessment of Executive Function in Everyday Life—Psychometric Properties of the Norwegian Adaptation of the Children’s Cooking Task

Background: There are few standardized measures available to assess executive function (EF) in a naturalistic setting for children. The Children’s Cooking Task (CCT) is a complex test that has been specifically developed to assess EF in a standardized open-ended environment (cooking). The aim of the present study was to evaluate the internal consistency, inter-rater reliability, sensitivity and specificity, and also convergent and divergent validity of the Norwegian version of CCT among children with pediatric Acquired Brain Injury (pABI) and healthy controls (HCs).

Methods: The present study has a cross-sectional design, based on baseline data derived from a multicenter RCT. Seventy-five children with pABI from two university hospitals with parent-reported executive dysfunction and minimum of 12 months since injury/completed cancer therapy, as well as 59 HCs aged 10–17 years, were assessed with CCT using total errors as the main outcome measure. The pABI group completed tests assessing EF (i.e., inhibition, cognitive flexibility, working memory, and planning) on the impairment level within the ICF framework (performance-based neuropsychological tests and the Behavioral Assessment of the Dysexecutive Syndrome for Children), and on the participation level (questionnaires). In addition, they completed tests of intellectual ability, processing speed, attention, learning, and memory. Finally, overall functional outcome (pediatric Glasgow Outcome Scale-Extended) was evaluated for the children with pABI.

Results: Acceptable internal consistency and good inter-rater reliability were found for the CCT. Children with pABI performed significantly worse on the CCT than the HCs. The CCT identified group membership, but the sensitivity and specificity were overall classified as poor. Convergent validity was demonstrated by associations between the CCT and performance-based tests assessing inhibition, cognitive flexibility, and working memory, as well as teacher-reported executive dysfunction (questionnaires). Divergent validity was supported by the lack of association with performance-based measures of learning and memory, attention, and verbal intellectual ability. However, there was a moderate association between the CCT and performance-based tests of processing speed. Lastly, better performance on the CCT was associated with a better functional outcome.

Conclusion: Our study with a relatively large sample of children with pABI and HC’s demonstrated good psychometric properties of the CCT. CCT performance was associated with the overall level of disability and function, suggesting that CCT is related to the level of activity in everyday life and participation in society. Hence, our study suggests that the CCT has the potential to advance the assessment of EF by providing a valid analysis of real-world performance. Nevertheless, further research is needed on larger samples, focusing on predictors of task performance, and evaluating the ability of CCT to detect improvement in EF over time. The patterns of error and problem-solving strategies evaluated by the CCT could be used to inform neuropsychological rehabilitation treatmentand represent a more valid outcome measure of rehabilitation interventions.

Exposure to Violence Variety as a Risk Factor for Cigarette Smoking: Relevance of Sensation-Seeking and Impulsivity as Mediators

BACKGROUND

Prior research has indicated that exposure to violence is a risk factor associated with cigarette smoking. However, the relevance of variety of exposure for predicting this outcome has remained underexplored. This is problematic, as increased variety of exposure may represent a measure of severity of trauma exposure with less recall bias than other measures. Further, related constructs of sensation-seeking and impulsivity have yet to be investigated as mediators of this relationship. It is predicted that increased variety of exposure to violence results in dysfunctional variation in these constructs, leading to increased daily cigarette use.

METHODS

The present study utilizes data from the first three waves of the Pathways to Desistance study to examine these relationships. Generalized structural equation modeling is used to identify direct and indirect effects of interest. A bootstrap resampling process was used to compute normalized standard errors so that indirect effects were not biased.

RESULTS

Results indicated that lifetime exposure to violence variety prior to baseline predicted increased daily cigarette use at follow-up. Neither sensation-seeking nor impulsivity were significant mediators when both constructs were included in the model, but impulsivity emerged as a significant mediator when separate mediation models were estimated for each construct.

CONCLUSIONS

The findings indicate the potential utility of screening for variety of exposure to violence to determine adolescents who may be at-risk for high frequency cigarette smoking. Programming focused on impulsivity may play a role in addressing cigarette smoking issues stemming from exposure to violence.

Reduced neuronal population in the dorsolateral prefrontal cortex in infant macaques infected with simian immunodeficiency virus (SIV)

Pediatric HIV infection remains a global health crisis with an estimated 150,000 new mother-to-child (MTCT) infections each year. Antiretroviral therapy (ART) has improved childhood survival, but only an estimated 53% of children worldwide have access to treatment. Adding to the health crisis is the neurological impact of HIV on the developing brain, in particular cognitive and executive function, which persists even when ART is available. Imaging studies suggest structural, connectivity, and functional alterations in perinatally HIV-infected youth. However, the paucity of histological data limits our ability to identify specific cortical regions that may underlie the clinical manifestations. Utilizing the pediatric simian immunodeficiency virus (SIV) infection model in infant macaques, we have previously shown that early-life SIV infection depletes the neuronal population in the hippocampus. Here, we expand on these previous studies to investigate the dorsolateral prefrontal cortex (dlPFC). A total of 11 ART-naïve infant rhesus macaques (Macaca mulatta) from previous studies were retrospectively analyzed. Infant macaques were either intravenously (IV) inoculated with highly virulent SIVmac251 at ~1 week of age and monitored for 6-10 weeks or orally challenged with SIVmac251 from week 9 of age onwards with a monitoring period of 10-23 weeks post-infection (19-34 weeks of age), and SIV-uninfected controls were euthanized at 16-17 weeks of age. Both SIV-infected groups show a significant loss of neurons along with evidence of ongoing neuronal death. Oral- and IV-infected animals showed a similar neuronal loss which was negatively correlated to chronic viremia levels as assessed by an area under the curve (AUC) analysis. The loss of dlPFC neurons may contribute to the rapid neurocognitive decline associated with pediatric HIV infection.

Kognitive Fähigkeiten von Kindern mit Defiziten in der Sprachentwicklung – Ergebnisse zur WPPSI-IV

In dieser Case-Control-Studie wurden kognitive Leistungen (WPPSI-IV) von Vorschulkindern mit rezeptiven und/oder expressiven Sprachdefiziten mit den Leistungen einer nach Alter, Geschlecht gematchten sprachunauffälligen Kontrollgruppe verglichen (N = 186).

Insbesondere die sprachbezogenen Indizes sowie umgebungsbedingte Faktoren, wie mütterlicher Bildungshintergrund und Mehrsprachigkeit, werden in der Teilstichprobe der sprachbeeinträchtigten Kinder exploriert.

Jeweils die Leistungen der beiden Gruppen im Sprachverständnis, Wortschatzerwerb, Allgemeinen Fähigkeitsindex und Gesamt-IQ unterscheiden sich signifikant mit kleinen bis mittleren Effekten voneinander.

Signifikante Unterschiede der sprachbezogenen Indizes in Abhängigkeit des mütterlichen Bildungsniveaus und der Ein-/Mehrsprachigkeit der Kinder verweisen auf die hohe Bedeutung der häuslichen Umgebung für die Sprachentwicklung. Praktische Implikationen bezüglich des Einsatzes der WPPSI-IV bei sprachbeeinträchtigen Kindern werden erörtert.

Social impairment in children with epilepsy assessed by the social responsiveness scale

Children with epilepsy are at risk for impaired social cognition and autism. We aimed at evaluating the utility of the social responsiveness scale (SRS) for assessment of social impairment in these children. Prospective study; the SRS was applied to a group of children with epilepsy and a healthy control group. Intellectual disability in the epilepsy group was assessed utilizing adapted versions of the Wechsler Intelligence and adaptive behavior scales. One hundred and one children with epilepsy and 92 healthy children were included. The majority of children in both groups had normal SRS scores. Significant differences were identified in children with high total scores indicating significant deficiencies in reciprocal social behavior; high scores were found in 16% of children with epilepsy versus 7% of normal children, p < .05, particularly involving social communication, p < .05. Intellectual disability was identified in 42% of children with epilepsy, particularly processing speed index, p < .001. Intellectual disability had a significant effect on total scores, p = .016. Children with epilepsy have increased risk of social impairments. Social impairments are more likely in the presence of intellectual disability. The SRS is a quick identification tool that can be employed in the outpatient setting.

Relevance of the dual systems model for predicting drug/alcohol dependence in early adulthood among previously adjudicated young adults

BACKGROUND

While the dual system model has been found to have utility for predicting drug use, examinations have yet to extend to the clinically relevant issue of drug/alcohol dependence. This study sought to provide better understanding of how the dual systems model constructs (impulse control and sensation-seeking) predicted risk for drug/alcohol dependence in early adulthood among a sample of young adults who were adjudicated for a serious offense as minors.

METHODS

Data from several waves of the Pathways to Desistance data were used in analyses. Logistic regression was used to model covariate effects on drug/alcohol dependence risk.

RESULTS

Findings indicated that lower impulse control predicted increased odds of meeting criteria for drug/alcohol dependence in early adulthood. Sensation-seeking was not a significant predictor of drug/alcohol dependence risk at follow-up.

CONCLUSIONS

Lower impulse control was predictive of drug/alcohol dependence risk. Prevention programming should seek to boost impulse control during adolescence to mitigate this risk and treatment programming should focus on impulse control training in order to treat drug/alcohol dependence in inpatient and outpatient contexts.

The clinical utility of the behavior rating inventory of executive function in preschool children with a history of perinatal stroke

The current study examined the utility of the Behavior Rating Inventory of Executive Function-Preschool Version (BRIEF-P) in capturing emerging deficits in executive function in preschool children with a history of perinatal stroke. Parents and teachers of 55 clinically referred preschool children (3-5 years of age) provided ratings using the BRIEF-P. Both parent (M = 56.02, p = .001) and teacher ratings (M = 58.61, p = .002) indicated significant scale elevations for working memory compared to the normative sample, albeit below the clinically elevated range. Parent and teacher ratings were low-to-moderately correlated (r = .05-.55). Greater deficits in working memory (r = -.58), inhibition (r = -.45), and planning/organization (r = -.51), as rated by teachers, were associated with lower intellectual functioning. Parents' ratings were not associated with intellectual functioning. Further, no neurological or personal characteristics were associated with ratings of executive function. The current study demonstrates children with a history of perinatal stroke are, on average, following a normal trajectory of executive function development according to BRIEF-P ratings. The needs for multi-informant ratings and performance-based measures to comprehensively assess executive functioning in preschoolers with a history of stroke are discussed.

Prefrontal Cortex Development in Health and Disease: Lessons from Rodents and Humans

The role of the prefrontal cortex (PFC) takes center stage among unanswered questions in modern neuroscience. The PFC has a Janus-faced nature: it enables sophisticated cognitive and social abilities that reach their maximum expression in humans, yet it underlies some of the devastating symptoms of psychiatric disorders. Accordingly, appropriate prefrontal development is crucial for many high-order cognitive abilities and dysregulation of this process has been linked to various neuropsychiatric diseases. Reviewing recent advances in the field, with a primary focus on rodents and humans, we highlight why, despite differences across species, a cross-species approach is a fruitful strategy for understanding prefrontal development. We briefly review the developmental contribution of molecules and extensively discuss how electrical activity controls the early maturation and wiring of prefrontal areas, as well as the emergence and refinement of input-output circuitry involved in cognitive processing. Finally, we highlight the mechanisms of developmental dysfunction and their relevance for psychiatric disorders.

A systematic review of transcranial direct current stimulation effects in attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) stands out as the most prevalent neurodevelopmental disorder of childhood, with global prevalence ranging from 3.4% to 7•2%. Its cognitive symptoms result from the combination of complex etiological processes encompassing genetic and environmental components. Available therapeutic approaches are associated with significant challenges such as modest efficacy or side effects. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in neuropsychiatric disorders. Trials investigating its applicability in ADHD have showed propitious, however, still preliminary findings.

METHODS

We performed a systemic review by searching on Medline, Cochrane Library, Web of Science, ScienceDirect and Embase using the descriptors: "attention-deficit/hyperactivity disorder" or "ADHD"; and "transcranial direct current stimulation" or "tDCS"; following PRISMA guidelines.

RESULTS

A total of 383 articles were identified. After removing duplicates, 45 studies were assessed for eligibility, and after careful review, 11 manuscripts applying tDCS in ADHD were included. Significant improvements in attention, inhibitory control and working memory were reported, in addition to increased brain connectivity following use of active tDCS.

LIMITATIONS

The main limitation was the small number of trials investigating use of tDCS in ADHD. Study methods and outcome measures were quite variable, and generally did not include long-term follow-up.

CONCLUSIONS

Although the extent literature indicates promising findings, the available data remains highly preliminary. Further trials evaluating the efficacy of tDCS for ADHD, with longer follow-up, are necessary. These studies will be needed to determine the optimal protocol for clinical efficacy.

Working memory and decision making in children with ADHD: an analysis of delay discounting with the use of the dual-task paradigm

BACKGROUND

Deficits in working memory tasks have been widely documented in Attention Deficit Hyperactivity Disorder (ADHD) studies. The aim of this study is to evaluate the effects of working memory load in impulsivity during decision-making processes. A delayed discounting (DD) paradigm was used, comparing children with ADHD and age-matched controls.

METHOD

Thirty-two children equally divided between typically developing and ADHD, from 8 to 10 years of age were assigned to sessions of a dual-task paradigm. In the primary task the child has to choose between two different amounts of money at different time delays, while in the secondary task the child has to repeat a random series of digits with different lengths. The experiment was conducted in a school setting.

RESULTS

Compared to peers with typical development, delayed discounting was significantly stronger in children with ADHD and discounting rates increased in both groups for heavier memory loads. Furthermore, the memory load impact on frequency of immediate rewards was stronger in children with ADHD compared to typically developing children.

DISCUSSION

Results are discussed in terms of the relation between working memory load and decision-making processes, their impact on impulsive behaviour in ADHD and the need for future research to understand possible neurocognitive correlates and use that information to develop better inclusive policies.

Developmental divergence of structural brain networks as an indicator of future cognitive impairments in childhood brain injury: Executive functions

Brain insults during childhood can perturb the already non-linear trajectory of typical brain maturation. The diffuse effects of injury can be modelled using structural covariance networks (SCN), which change as a function of neurodevelopment. However, SCNs are estimated at the group-level, limiting applicability to predicting individual-subject outcomes. This study aimed to measure the divergence of the brain networks in paediatric traumatic brain injury (pTBI) patients and controls, and investigate relationships with executive functioning (EF) at 24 months post-injury. T1-weighted MRI acquired acutely in 78 child survivors of pTBI and 33 controls underwent 3D-tissue segmentation to estimate cortical thickness (CT) across 68 atlas-based regions-of-interest (ROIs). Using an 'add-one-patient' approach, we estimate a developmental divergence index (DDI). Our approach adopts a novel analytic framework in which age-appropriate reference networks to calculate the DDI were generated from control participants from the ABIDE dataset using a sliding-window approach. Divergence from the age-appropriate SCN was related to reduced EF performance and an increase in behaviours related to executive dysfunctions. The DDI measure showed predictive value with regard to executive functions, highlighting that early imaging can assist in prognosis for cognition.

The feasibility and acceptability of goal management training of executive functions in children with spina bifida and acquired brain injury

Executive dysfunction causes significant real-life disability for children with spina bifida (SB) and acquired brain injury (ABI), and efficient interventions are needed. Goal Management Training (GMT) is a cognitive rehabilitation intervention for improving executive function (EF) that has received empirical support in studies of adults with SB and ABI. The purpose of this study was to determine the feasibility and acceptability of a newly developed pediatric GMT protocol (pGMT). Thirteen children (7 boys, 10-16 years) with SB (n = 4), traumatic brain injury (n = 8), and encephalitis (n = 1) were included, based upon the presence of EF problems as described by parents. The participants received 21 h of pGMT, using inpatient intervention periods, followed by 4 h of pGMT outpatient guidance over 8 weeks. Notably, pGMT was found to be both feasible and acceptable, with satisfactory compliance for the children, parents and teachers, in addition to being considered acceptable by all participants. Furthermore, a reliable change in daily life EF was reported by the parents for 2 children. And, some children obtained scores below clinical cut-off on a measure of parent reported real-life EF after intervention. Hence, findings suggest that a randomized controlled trial of pGMT, with a larger sample size, should be conducted.

Development of Network Topology and Functional Connectivity of the Prefrontal Cortex

The prefrontal cortex (PFC) comprises distinct regions and networks that vary in their trajectories across development. Further understanding these diverging trajectories may elucidate the neural mechanisms by which distinct PFC regions contribute to cognitive maturity. In particular, it remains unclear whether PFC regions of distinct network affiliations differ in topology and their relationship to cognition. We examined 615 individuals (8–21 years) to characterize age-related effects in participation coefficient of 28 PFC regions of distinct networks, evaluating connectivity profiles of each region to understand patterns influencing topological maturity. Findings revealed that PFC regions of attention, frontoparietal, and default mode networks (DMN) displayed varying rates of decline in participation coefficient with age, characterized by stronger connectivity with each PFC’s respective network; suggesting that PFC regions largely aid network segregation. Conversely, PFC regions of the cinguloopercular/salience network increased in participation coefficient with age, marked by stronger between-network connections, suggesting that some PFC regions feature a distinctive ability to facilitate network integration. PFC topology of the DMN, in particular, predicted improvements in global cognition, including motor speed and higher order abilities. Together, these findings elucidate systematic differences in topology across PFC regions of different network affiliation, representing important neural signatures of typical brain development.

Abnormal neural responses to emotional stimuli in children with primary monosymptomatic nocturnal enuresis

Nocturnal enuresis (NE) is a common disorder in school-aged children that has been reported to affect nearly 10% of 7-year-old children and affects both the children and their families. Previous studies have shown that the risk of psychosocial difficulties in children with enuresis is elevated. Thus, children with NE may experience negative effects on psychosocial health or emotion processing. Therefore, the aim of this study was to investigate the potential disturbance in emotional processing in children with NE using functional magnetic resonance imaging (fMRI). In this work, we used fMRI and an affective picture task to evaluate brain response changes in children with NE. Two groups, one consisting of 22 children with primary monosymptomatic NE and one with 23 healthy controls, were scanned using fMRI. Compared to the healthy subjects, children with NE mainly showed increased activation when viewing negative vs. neutral pictures in the bilateral medial superior frontal gyrus that extended to the anterior cingulate cortex. Our results demonstrated that children with primary monosymptomatic NE showed abnormal neural responses to emotional stimuli and overactivation in the medial prefrontal and anterior cingulate cortices suggested that children with primary monosymptomatic NE may be hypersensitive in their sensory perception of negative pictures.

Parenting and the dysregulation profile predict executive functioning in children with acquired brain injury

Background: Children with acquired brain injury (ABI) present with high rates of psychological disorders commonly accompanied by deficits in hot and cold executive functions (EFs). Impairments in EFs have been reported to precede mental health problems. Moreover, children who are vulnerable to developing mental health problems in adulthood frequently present with a dysregulation profile in childhood, characterized by impairments in cognitive, behavioral and emotional regulation. Objective: To identify profiles of behaviors associated with impairment in hot and cold EFs and compare injury factors, environmental stressors and dysregulation profile between them. Methods: A latent profile analysis was conducted with 77 children with ABI aged between 6 and 12. Injury factors, child IQ, environmental stressors and the dysregulation profile were compared between these behavioral profiles. Logistic regressions were conducted to predict profile membership. Results: Two profiles were identified: Profile M, with mild deficits (1-2 SD above the mean) in working memory and social skills, and profile C, presenting clinically significant deficits (2-3 SD above the mean) in shift, initiate, working memory, planning and social skills and mild deficits in inhibit, emotional control and task monitor. Proximal environmental stressors (dysfunctional parenting practices, parental stress, parent's executive dysfunction, anxiety-trait, and depressive symptoms) and dysregulation symptoms predicted profile membership, whereas injury factors, child IQ and distal environmental stressors did not. Conclusion: Following ABI, children with profile C are at risk of mental health problems and present with more proximal stressors. The dysregulation profile may be useful as a proxy for risk for later mental health problems in children with ABI.

How Do Parents Influence Child Disruptive Behavior After Acquired Brain Injury? Evidence From a Mediation Model and Path Analysis

OBJECTIVES

Children with acquired brain injury (ABI) can present with disruptive behavior, which is often a consequence of injury and parent factors. Parent factors are associated with child disruptive behavior. Furthermore, disinhibition in the child also leads to disruptive behavior. However, it is unclear how these factors interact. We investigated whether parental factors influence child disruptive behavior following ABI and how these factors interact.

METHODS

Parents of 77 children with ABI participated in the study. Parent factors (executive dysfunction, trait-anxiety), potential intervention targets (dysfunctional parenting practices, parental stress, child disinhibition), and child disruptive behavior were assessed. A hypothetical model based on the literature was tested using mediation and path analysis.

RESULTS

Mediation analysis revealed that child disinhibition and dysfunctional parenting practices mediated the association of parent factors and child disruptive behavior. Parents' executive dysfunction mediated the association of dysfunctional parenting practices, parental stress and parent trait-anxiety. Parenting practices mediated the association of executive dysfunction and child disruptive behavior. Path analysis indices indicated good model adjustment. Comparative and Tucker-Lewis Index were &gt;0.95, and the root mean square error of approximation was 0.059, with a chi-square of 0.25.

CONCLUSIONS

A low level of parental trait-anxiety may be required to reduce dysfunctional parenting practices and child disinhibition. Impairments in child disinhibition can be exacerbated when parents present with high trait-anxiety. Child disinhibition is the major contributor of disruptive behavior reported by parents and teachers. The current study provides evidence of parent anxiety and child disinhibition as possible modifiable intervention targets for reducing child disruptive behavior. (JINS, 2019, 25, 237-248).

Exposure to polybrominated diphenyl ethers (PBDEs) and child behavior: Current findings and future directions

Polybrominated diphenyl ethers (PBDEs) are recognized neurotoxicants, but the extent to which PBDEs influence various domains of behavior in children is not fully understood. As such, we reviewed epidemiologic studies published to date to provide an overview of the current state of knowledge on PBDEs' potential role in behavioral development. We identified 19 epidemiologic studies reporting on associations of prenatal and childhood concentrations of PBDEs with behaviors assessed in children from 1 to 12years, including executive function, attention, externalizing and internalizing behaviors, adaptive skills, and social behaviors/Autism Spectrum Disorder (ASD). While the mechanisms of PBDE neurotoxicity in humans are still not clearly elucidated, findings from this review indicate that PBDE exposure during fetal development is associated with impairments in executive function and poorer attentional control in children. Results from large prospective cohorts demonstrate that prenatal and postnatal PBDE exposure adversely impacts externalizing behavior (e.g., hyperactivity and conduct problems). Additional studies are needed to determine whether PBDEs are associated with internalizing problems, adaptive skills, and social behaviors/ASD in children. Future studies will help better understand the potential neurotoxic effects of PBDE exposures during adolescence, possible sex-dependent effects, and the impact of exposure to BDE-209 and alternative flame retardants. Future studies should also examine chemical mixtures to capture real-world exposures when examining PBDEs and their impact on various behavioral domains in the context of multiple chemical exposures.

Relationship Between Executive Functioning and Symptoms of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder in 6-8 Year Old Children

This study examined relationships between executive functioning (EF) and ADHD/ASD symptoms in 339 6-8 year-old children to characterise EF profiles associated with ADHD and ADHD + ASD. ADHD status was assessed using screening surveys and diagnostic interviews. ASD symptoms were measured using the Social Communication Questionnaire, and children completed assessments of EF. We found the EF profile of children with ADHD + ASD did not differ from ADHD-alone and that lower-order cognitive skills contributed significantly to EF. Dimensionally, ASD and inattention symptoms were differentially associated with EF, whereas hyperactivity symptoms were unrelated to EF. Differences between categorical and dimensional findings suggest it is important to use both diagnostic and symptom based approaches in clinical settings when assessing these children's functional abilities.

ADHD patients fail to maintain task goals in face of subliminally and consciously induced cognitive conflicts

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) patients have been reported to display deficits in action control processes. While it is known that subliminally and consciously induced conflicts interact and conjointly modulate action control in healthy subjects, this has never been investigated for ADHD.

METHOD

We investigated the (potential) interaction of subliminally and consciously triggered response conflicts in children with ADHD and matched healthy controls using neuropsychological methods (event-related potentials; ERPs) to identify the involved cognitive sub-processes.

RESULTS

Unlike healthy controls, ADHD patients showed no interaction of subliminally and consciously triggered response conflicts. Instead, they only showed additive effects as their behavioural performance (accuracy) was equally impaired by each conflict and they showed no signs of task-goal shielding even in cases of low conflict load. Of note, this difference between ADHD and controls was not rooted in early bottom-up attentional stimulus processing as reflected by the P1 and N1 ERPs. Instead, ADHD showed either no or reversed modulations of conflict-related processes and response selection as reflected by the N2 and P3 ERPs.

CONCLUSION

There are fundamental differences in the architecture of cognitive control which might be of use for future diagnostic procedures. Unlike healthy controls, ADHD patients do not seem to be endowed with a threshold which allows them to maintain high behavioural performance in the face of low conflict load. ADHD patients seem to lack sufficient top-down attentional resources to maintain correct response selection in the face of conflicts by shielding the response selection process from response tendencies evoked by any kind of distractor.

Found in translation: Understanding the biology and behavior of experimental traumatic brain injury

The aim of this review is to discuss in greater detail the topics covered in the recent symposium entitled "Traumatic brain injury: laboratory and clinical perspectives," presented at the 2014 International Behavioral Neuroscience Society annual meeting. Herein, we review contemporary laboratory models of traumatic brain injury (TBI) including common assays for sensorimotor and cognitive behavior. New modalities to evaluate social behavior after injury to the developing brain, as well as the attentional set-shifting test (AST) as a measure of executive function in TBI, will be highlighted. Environmental enrichment (EE) will be discussed as a preclinical model of neurorehabilitation, and finally, an evidence-based approach to sports-related concussion will be considered. The review consists predominantly of published data, but some discussion of ongoing or future directions is provided.

Cognitive effects following acute wild blueberry supplementation in 7- to 10-year-old children

PURPOSE

Previously, anthocyanin-rich blueberry treatments have shown positive effects on cognition in both animals and human adults. However, little research has considered whether these benefits transfer to children. Here we describe an acute time-course and dose-response investigation considering whether these cognitive benefits extend to children.

METHODS

Using a double-blind cross-over design, on three occasions children (n = 21; 7-10 years) consumed placebo (vehicle) or blueberry drinks containing 15 or 30 g freeze-dried wild blueberry (WBB) powder. A cognitive battery including tests of verbal memory, word recognition, response interference, response inhibition and levels of processing was performed at baseline, and 1.15, 3 and 6 h following treatment.

RESULTS

Significant WBB-related improvements included final immediate recall at 1.15 h, delayed word recognition sustained over each period, and accuracy on cognitively demanding incongruent trials in the interference task at 3 h. Importantly, across all measures, cognitive performance improved, consistent with a dose-response model, with the best performance following 30 g WBB and the worst following vehicle.

CONCLUSION

Findings demonstrate WBB-related cognitive improvements in 7- to 10-year-old children. These effects would seem to be particularly sensitive to the cognitive demand of task.

Neonatal MRI is associated with future cognition and academic achievement in preterm children

School-age children born preterm are particularly at risk for low mathematical achievement, associated with reduced working memory and number skills. Early identification of preterm children at risk for future impairments using brain markers might assist in referral for early intervention. This study aimed to examine the use of neonatal magnetic resonance imaging measures derived from automated methods (Jacobian maps from deformation-based morphometry; fractional anisotropy maps from diffusion tensor images) to predict skills important for mathematical achievement (working memory, early mathematical skills) at 5 and 7 years in a cohort of preterm children using both univariable (general linear model) and multivariable models (support vector regression). Participants were preterm children born <30 weeks' gestational age and healthy control children born ≥37 weeks' gestational age at the Royal Women's Hospital in Melbourne, Australia between July 2001 and December 2003 and recruited into a prospective longitudinal cohort study. At term-equivalent age ( ±2 weeks) 224 preterm and 46 control infants were recruited for magnetic resonance imaging. Working memory and early mathematics skills were assessed at 5 years (n = 195 preterm; n = 40 controls) and 7 years (n = 197 preterm; n = 43 controls). In the preterm group, results identified localized regions around the insula and putamen in the neonatal Jacobian map that were positively associated with early mathematics at 5 and 7 years (both P < 0.05), even after covarying for important perinatal clinical factors using general linear model but not support vector regression. The neonatal Jacobian map showed the same trend for association with working memory at 7 years (models ranging from P = 0.07 to P = 0.05). Neonatal fractional anisotropy was positively associated with working memory and early mathematics at 5 years (both P < 0.001) even after covarying for clinical factors using support vector regression but not general linear model. These significant relationships were not observed in the control group. In summary, we identified, in the preterm brain, regions around the insula and putamen using neonatal deformation-based morphometry, and brain microstructural organization using neonatal diffusion tensor imaging, associated with skills important for childhood mathematical achievement. Results contribute to the growing evidence for the clinical utility of neonatal magnetic resonance imaging for early identification of preterm infants at risk for childhood cognitive and academic impairment.

Alterations of resting state networks and structural connectivity in relation to the prefrontal and anterior cingulate cortices in late prematurity

Late preterm birth is increasingly recognized as a risk factor for cognitive and social deficits. The prefrontal cortex is particularly vulnerable to injury in late prematurity because of its protracted development and extensive cortical connections. Our study examined children born late preterm without access to advanced postnatal care to assess structural and functional connectivity related to the prefrontal cortex. Thirty-eight preadolescents [19 born late preterm (34-36 /7 weeks gestational age) and 19 at term] were recruited from a developing community in Brazil. Participants underwent neuropsychological testing. Individuals underwent three-dimensional T1-weighted, diffusion-weighted, and resting state functional MRI. Probabilistic tractography and functional connectivity analyses were carried out using unilateral seeds combining the medial prefrontal cortex and the anterior cingulate cortex. Late preterm children showed increased functional connectivity within regions of the default mode, salience, and central-executive networks from both right and left frontal cortex seeds. Decreased functional connectivity was observed within the right parahippocampal region from left frontal seeding. Probabilistic tractography showed a pattern of decreased streamlines in frontal white matter pathways and the corpus callosum, but also increased streamlines in the left orbitofrontal white matter and the right frontal white matter when seeded from the right. Late preterm children and term control children scored similarly on neuropsychological testing. Prefrontal cortical connectivity is altered in late prematurity, with hyperconnectivity observed in key resting state networks in the absence of neuropsychological deficits. Abnormal structural connectivity indicated by probabilistic tractography suggests subtle changes in white matter development, implying disruption of normal maturation during the late gestational period.

Assessing cognitive improvement in people with Down syndrome: important considerations for drug-efficacy trials

Experimental research over just the past decade has raised the possibility that learning deficits connected to Down syndrome (DS) might be effectively managed by medication. In the current chapter, we touch on some of the work that paved the way for these advances and discuss the challenges associated with translating them. In particular, we highlight sources of phenotypic variability in the DS population that are likely to impact performance assessments. Throughout, suggestions are made on how to detect meaningful changes in cognitive-adaptive function in people with DS during drug treatment. The importance of within-subjects evaluation is emphasized.

Performance enhancement at the cost of potential brain plasticity: neural ramifications of nootropic drugs in the healthy developing brain

Cognitive enhancement is perhaps one of the most intriguing and controversial topics in neuroscience today. Currently, the main classes of drugs used as potential cognitive enhancers include psychostimulants (methylphenidate (MPH), amphetamine), but wakefulness-promoting agents (modafinil) and glutamate activators (ampakine) are also frequently used. Pharmacologically, substances that enhance the components of the memory/learning circuits—dopamine, glutamate (neuronal excitation), and/or norepinephrine—stand to improve brain function in healthy individuals beyond their baseline functioning. In particular, non-medical use of prescription stimulants such as MPH and illicit use of psychostimulants for cognitive enhancement have seen a recent rise among teens and young adults in schools and college campuses. However, this enhancement likely comes with a neuronal, as well as ethical, cost. Altering glutamate function via the use of psychostimulants may impair behavioral flexibility, leading to the development and/or potentiation of addictive behaviors. Furthermore, dopamine and norepinephrine do not display linear effects; instead, their modulation of cognitive and neuronal function maps on an inverted-U curve. Healthy individuals run the risk of pushing themselves beyond optimal levels into hyperdopaminergic and hypernoradrenergic states, thus vitiating the very behaviors they are striving to improve. Finally, recent studies have begun to highlight potential damaging effects of stimulant exposure in healthy juveniles. This review explains how the main classes of cognitive enhancing drugs affect the learning and memory circuits, and highlights the potential risks and concerns in healthy individuals, particularly juveniles and adolescents. We emphasize the performance enhancement at the potential cost of brain plasticity that is associated with the neural ramifications of nootropic drugs in the healthy developing brain.

Predicting neurocognitive and behavioural outcome after early brain insult

AIMS

The aims of the study were to investigate (1) the impact of age at brain insult on functional outcome and (2) the influence of insult and environmental factors on cognitive and behavioural outcomes.

METHOD

The study was a cross-sectional, retrospective observational study, involving 138 children (76 males, 62 females; mean age 13y 1mo, SD 1y 11mo, range 10–16y) with magnetic resonance imaging (MRI) evidence of focal brain insult sustained from the first trimester of pregnancy to adolescence. Children underwent MRI and intellectual, executive, behavioural, and social evaluation. Outcome predictors were insult (lesion location, laterality, and extent, history of seizures, age at insult) and environmental (social risk and family function) factors.

RESULTS

Focal insult before the age of 3 years was associated with poorer outcomes than insult after the age of 3 years across all domains. For IQ outcomes, insult characteristics and seizures were highly predictive. For executive and behavioural domains, family function and social risk had the greatest impact. Earlier age at insult predicted poorer social competence. INTERPRETATION Focal brain insult before age 3 years has devastating consequences for children's development. Findings suggest that greater emphasis should be placed on providing early intervention for children who sustain early focal brain insults.

Age, sex, and performance influence the visuospatial working memory network in childhood

This study describes the influence of age, sex, and working memory (WM) performance on the visuospatial WM network. Thirty-nine healthy children (7-12 years) completed a dot location functional magnetic resonance imaging (fMRI) task. Percent signal change measured the intensity and laterality indices measured the asymmetry of activation in frontal and parietal brain regions. Old children showed greater intensity of activation in parietal regions than young children but no differences in lateralization were observed. Intensity of activation was similar across sex and WM performance groups. Girls and high WM performers showed more right-sided lateralization of parietal regions than boys and low WM performers.

Traumatic injury to the immature frontal lobe: a new murine model of long-term motor impairment in the absence of psychosocial or cognitive deficits

Traumatic brain injury in children commonly involves the frontal lobes and is associated with distinct structural and behavioral changes. Despite the clinical significance of injuries localized to this region during brain development, the mechanisms underlying secondary damage and long-term recovery are poorly understood. Here, we have characterized the first model of unilateral focal traumatic injury to the developing frontal lobe. Male C57Bl/6J mice at postnatal day (p)21, an age approximating a toddler-aged child, received a controlled cortical impact or sham surgery to the left frontal lobe and were euthanized 1 or 7 days later. A necrotic cavity and local inflammatory response were largely confined to the unilateral frontal lobe, dorsal corpus callosum and striatum anterior to the bregma. While cell death and accumulated β-amyloid precursor protein were characteristic features of the pericontusional motor cortex, corpus callosum, cingulum and dorsal striatum, underlying structures including the hippocampus showed no overt pathology. To determine the long-term functional consequences of injury at p21, two additional cohorts were subjected to a battery of behavioral tests in adolescence (p35-45) or adulthood (p70-80). In both cohorts, brain-injured mice showed normal levels of anxiety, sociability, spatial learning and memory. The signature phenotypic features were deficits in motor function and motor learning, coincident with a reduction in ipsilateral cortical brain volumes. Together, these findings demonstrate classic morphological features of a focal traumatic injury, including early cell death and axonal injury, and long-term volumetric loss of cortical volumes. The presence of deficits in sensorimotor function and coordination in the absence of abnormal findings related to anxiety, sociability and memory likely reflects several variables, including the unique location of the injury and the emergence of favorable compensatory mechanisms during subsequent brain development.

A developmental systems approach to executive function

According to recent claims from behavior genetics, executive function (EF) is almost entirely heritable. The implications of this claim are significant, given the importance of EF in academic, social, and psychological domains. This paper critically examines the behavior genetics approach to explaining individual differences in EF and proposes a relational developmental systems model that integrates both biological and social factors in the development of EF and the emergence of individual differences in EF. Problems inherent to behavioral genetics research are discussed, as is neuroscience research that emphasizes the plasticity of the prefrontal cortex. Empirical evidence from research on stress, social interaction, and intervention and training demonstrates that individual differences in EF are experience-dependent. Taken together, these findings challenge the claim that EF is almost entirely genetic but are consistent with an approach that considers biological differences in the context of social interaction.

Cognitive recovery and development after traumatic brain injury in childhood: a person-oriented, longitudinal study

Influence of childhood traumatic brain injury (TBI) on cognitive recovery and subsequent development is poorly understood. In this longitudinal study we used cluster analysis to explore acute stage individual profiles of injury age and cognition in 118 children with traumatic brain injury. Repeated measures of cognitive function were conducted at 30 months, indicating recovery, and 10 years post-injury, indicating development. Nine clusters were identified. Recovery was evident in three clusters, two of them with low functioning profiles. Developmental gains occurred for three clusters and an acute profile of higher freedom from distractibility (FFD) and lower processing speed (PS) was related to positive differences. One cluster, average low functioning and especially low verbal comprehension, demonstrated a slower development than peers. This suggests that developmental change after TBI in childhood takes place on a continuum, with both chance of long-term catching up, and risk of poor development. An acute profile of higher FFD and lower PS seemed to reflect injury consequences and were followed by developmental gains. These results challenge previous findings, and warrant further investigation.

Executive functioning in children with unilateral cerebral palsy: protocol for a cross-sectional study

INTRODUCTION

Early brain injury, as found in children with unilateral cerebral palsy (CP), may cause deficits in higher-order cognitive tasks known as executive functions (EF). EF has been conceptualised as comprised of four distinct yet inter-related components: (1) attentional control, (2) cognitive flexibility, (3) goal setting and (4) information processing. The aim of this study was to examine EF in children with unilateral CP and compare their performance with a typically developing reference group (TDC). The potential laterality effects of unilateral CP on EF will be explored, as will the relationship between the cognitive measures of EF, behavioural manifestations of EF, psychological functioning and clinical features of unilateral CP.

METHODS AND ANALYSIS

This cross-sectional study aims to recruit a total of 42 children with unilateral CP (21 right unilateral CP and 21 left unilateral CP) and 21 TDC aged between 8 and 16 years. Clinical severity will be described for gross motor function and manual ability. Outcomes for cognitive EF measureswill include subtests from the Wechsler Intelligence Scale for Children-Fourth Edition, Delis-Kaplan Executive Function System, Rey Complex Figure Test and the Test of Everyday Attention for Children. Behavioural manifestations of EF will be assessed using the Behaviour Rating Inventory of Executive Function, Parent and Teacher versions. Psychological functioning will be examined using the Strengths and Difficulties Questionnaire. Between-groups differences will be examined in a series of one-way analyses of covariance and followed up using linear comparisons. An overall composite of cognitive EF measures will be created. Bivariate correlations between the EF composite and psychological measures will be calculated.

ETHICS AND DISSEMINATION

This protocol describes a study that, to our knowledge, is the first to examine multiple components of EF using a cohort of children with unilateral CP. Exploration of potential laterality effects of EF among children with a congenital, unilateral brain injury is also novel. Possible relationships between EF and psychological functioning will also be investigated. Ethics have been obtained through the University of Queensland School of Psychology Ethics Committee and the Queensland Children's Health Services Human Research Ethics Committee. Results will be disseminated in peer reviewed publications and presentations at national and international conferences. This study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12611000263998).

Neuropsychological and neurobehavioral functioning in Duchenne muscular dystrophy: a review

Duchenne muscular dystrophy (DMD) is a genetic condition affecting predominantly boys that is characterized by fatal muscle weakness. While there is no cure, recent therapeutic advances have extended the lifespan of those with DMD considerably. Although the physiological basis of muscle pathology is well-documented, less is known regarding the cognitive, behavioral, and psychosocial functioning of those afflicted. Several lines of evidence point to central nervous system involvement as an organic feature of DMD, challenging our view of the disorder as strictly neuromuscular. This report provides a review of the literature on neuropsychological and neurobehavioral functioning in DMD. Recent research identifying associations with DMD and neuropsychiatric disorders is also discussed. Lastly, the review presents implications of findings related to nonmotor aspects of DMD for improving the quality of life in those affected. While the literature is often contradictory in nature, this review highlights some key findings for consideration by clinicians, educators and parents when developing therapeutic interventions for this population.

Long-term benefits of home-based preventive care for preterm infants: a randomized trial

BACKGROUND

We have previously reported improved caregiver mental health and infant behavior at 2 years following a home-based preventive care program for very preterm infants and their caregivers. This study aimed to determine the longer-term effectiveness of the program by reviewing caregivers and children at preschool age.

METHODS

One hundred twenty very preterm infants (<30 weeks' gestation) were randomly allocated to intervention (n = 61) or control (n = 59) groups. The intervention included 9 home visits over the first year of life targeting infant development, parent mental health, and the parent-infant relationship. The control group received standard care. At 4 years' corrected age, child cognitive, behavioral, and motor functioning and caregiver mental health were assessed.

RESULTS

At age 4 years, 105 (89%) children were reviewed. There was little evidence of differences in cognitive or motor functioning between groups. The intervention group had lower scores for child internalizing behaviors than the control group (mean difference -5.3, 95% confidence interval [CI] -9.6 to -0.9, P = .02). Caregivers in the intervention group had fewer anxiety symptoms (mean difference -1.8, 95% CI -3.3 to -0.4, P = .01) and were less likely to exhibit "at-risk" anxiety (odds ratio 0.3, 95% CI 0.1 to 0.7, P = .01) than those in the control group.

CONCLUSIONS

This home-based preventive care program for very preterm infants has selective long-term benefits, including less caregiver anxiety and reduced preschooler internalizing behaviors.

Overcoming residual interference in mental set switching: neural correlates and developmental trajectory

Mental set switching is a key facet of executive control measured behaviorally through reaction time or accuracy (i.e., 'switch costs') when shifting among task types. One of several experimentally dissociable influences on switch costs is 'task set inertia', conceptualized as the residual interference conferred when a previous stimulus-response tendency interferes with subsequent stimulus processing on a new task. Task set inertia is thought to represent the passive decay of the previous stimulus-response set from working memory, and its effects decrease with increased interstimulus interval. Closely spaced trials confer high task set inertia, while sparsely spaced trials confer low task set inertia. This functional magnetic resonance imaging (fMRI) study characterized, for the first time, two opposing brain systems engaged to resolve task set inertia: 1) a frontoparietal 'cortical control' network for overcoming high task set inertia interference and 2) a subcortical-motor network more active during trials with low task set inertia. These networks were distinct from brain regions showing general switching effects (i.e., switch>non-switch) and from other previously characterized interference effects. Moreover, there were ongoing maturational effects throughout adolescence for the brain regions engaged to overcome high task set inertia not seen for generalized switching effects. These novel findings represent a new avenue of exploration of cognitive set switching neural function.

Clinical research with transcranial direct current stimulation (tDCS): challenges and future directions

BACKGROUND

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity, direct current to cortical areas facilitating or inhibiting spontaneous neuronal activity. In the past 10 years, tDCS physiologic mechanisms of action have been intensively investigated giving support for the investigation of its applications in clinical neuropsychiatry and rehabilitation. However, new methodologic, ethical, and regulatory issues emerge when translating the findings of preclinical and phase I studies into phase II and III clinical studies. The aim of this comprehensive review is to discuss the key challenges of this process and possible methods to address them.

METHODS

We convened a workgroup of researchers in the field to review, discuss, and provide updates and key challenges of tDCS use in clinical research.

MAIN FINDINGS/DISCUSSION

We reviewed several basic and clinical studies in the field and identified potential limitations, taking into account the particularities of the technique. We review and discuss the findings into four topics: (1) mechanisms of action of tDCS, parameters of use and computer-based human brain modeling investigating electric current fields and magnitude induced by tDCS; (2) methodologic aspects related to the clinical research of tDCS as divided according to study phase (ie, preclinical, phase I, phase II, and phase III studies); (3) ethical and regulatory concerns; and (4) future directions regarding novel approaches, novel devices, and future studies involving tDCS. Finally, we propose some alternative methods to facilitate clinical research on tDCS.