Mental resources, processing speed, and inhibitory control: a developmental perspective

Executive functions in children with specific learning disorders: Shedding light on a complex profile through teleassessment

Executive Functions (EFs) are high-order cognitive processes relevant to learning and adaptation and frequently impaired in children with specific learning disorders (SLDs). This study aimed to investigate EFs in children with SLD and explore the role of specific EF-related subprocesses, such as stimuli processing and processing speed. Fifty-seven SLD and 114 typically developing (TD) children, matched for gender and age, completed four tasks measuring response inhibition, interference control, shifting, and updating on a web-based teleassessment platform. The results show that SLD children performed lower in all EF tasks than TD children, regardless of stimulus type and condition. Mediation analyses suggested that differences between the SLD and TD groups are mediated by EF-related subprocesses, offering an interpretative model of EF deficits in children with SLD.

Attentional control in middle childhood is highly dynamic-Strong initial distraction is followed by advanced attention control

The ability to shield against distraction while focusing on a task requires the operation of executive functions and is essential for successful learning. We investigated the short-term dynamics of distraction control in a data set of 269 children aged 4-10 years and 51 adults pooled from three studies using multilevel models. Participants performed a visual categorization task while a task-irrelevant sequence of sounds was presented which consisted of frequently repeated standard sounds and rarely interspersed novel sounds. On average, participants responded slower in the categorization task after novel sounds. This distraction effect was more pronounced in children. Throughout the experiment, the initially strong distraction effects declined to the level of adults in the groups of 6- to 10-year-olds. Such a decline was neither observed in the groups of the 4- and 5-year-olds, who consistently showed a high level of distraction, nor in adults, who showed a constantly low level of distraction throughout the experimental session. Results indicate that distraction control is a highly dynamic process that qualitatively and quantitatively differs between age groups. We conclude that the analysis of short-term dynamics provides valuable insights into the development of attention control and might explain inconsistent findings regarding distraction control in middle childhood. In addition, models of attention control need to be refined to account for age-dependent rapid learning mechanisms. Our findings have implications for the design of learning situations and provide an additional source of information for the diagnosis and treatment of children with attention deficit disorders.

Contributions of dopamine-related basal ganglia neurophysiology to the developmental effects of incentives on inhibitory control

Inhibitory control can be less reliable in adolescence, however, in the presence of rewards, adolescents' performance often improves to adult levels. Dopamine is known to play a role in signaling rewards and supporting cognition, but its role in the enhancing effects of reward on adolescent cognition and inhibitory control remains unknown. Here, we assessed the contribution of basal ganglia dopamine-related neurophysiology using longitudinal MR-based assessments of tissue iron in rewarded inhibitory control, using an antisaccade task. In line with prior work, we show that neutral performance improves with age, and incentives enhance performance in adolescents to that of adults. We find that basal ganglia tissue iron is associated with individual differences in the magnitude of this reward boost, which is strongest in those with high levels of tissue iron, predominantly in adolescence. Our results provide novel evidence that basal ganglia neurophysiology supports developmental effects of rewards on cognition, which can inform neurodevelopmental models of the role of dopamine in reward processing during adolescence.

Brain Activity During Antisaccades to Faces in Adolescence

Cognitive control and social perception both change during adolescence, but little is known of the interaction of these 2 processes. We aimed to characterize developmental changes in brain activity related to the influence of a social stimulus on cognitive control and more specifically on inhibitory control. Children (age 8-11, n = 19), adolescents (age 12-17, n = 20), and adults (age 24-40, n = 19) performed an antisaccade task with either faces or cars as visual stimuli, during functional magnetic resonance brain imaging. We replicate the finding of the engagement of the core oculomotor and face perception brain regions in all age-groups, with increased involvement of frontoparietal oculomotor regions and fusiform face regions with age. The antisaccade-related activity was modulated by stimulus category significantly only in adolescents. This interaction was observed mainly in occipitotemporal regions as well as in supplementary motor cortex and postcentral gyrus. These results indicate a special treatment of social stimuli during adolescence.

The Pause-then-Cancel model of human action-stopping: Theoretical considerations and empirical evidence

The ability to stop already-initiated actions is a key cognitive control ability. Recent work on human action-stopping has been dominated by two controversial debates. First, the contributions (and neural signatures) of attentional orienting and motor inhibition after stop-signals are near-impossible to disentangle. Second, the timing of purportedly inhibitory (neuro)physiological activity after stop-signals has called into question which neural signatures reflect processes that actually contribute to action-stopping. Here, we propose that a two-stage model of action-stopping - proposed by Schmidt and Berke (2017) based on subcortical rodent recordings - may resolve these controversies. Translating this model to humans, we first argue that attentional orienting and motor inhibition are inseparable because orienting to salient events like stop-signals automatically invokes broad motor inhibition, reflecting a fast-acting, ubiquitous Pause process. We then argue that inhibitory signatures after stop-signals differ in latency because they map onto two sequential stages: the salience-related Pause and a slower, stop-specific Cancel process. We formulate the model, discuss recent supporting evidence in humans, and interpret existing data within its context.

Speeding-up while growing-up: Synchronous functional development of motor and non-motor processes across childhood and adolescence

Describing the maturation of information processing in children is fundamental for developmental science. Although non-linear changes in reaction times have been well-documented, direct measurement of the development of the different processing components is lacking. In this study, electromyography was used to quantify the maturation of premotor and motor processes on a sample of 114 children (6–14 years-old) and 15 adults. Using a model-based approach, we show that the development of these two components is well-described by an exponential decrease in duration, with the decay rate being equal for the two components. These findings provide the first unbiased evidence in favour of the common developmental rate of nonmotor and motor processes by directly confronting rates of development of different processing components within the same task. This common developmental rate contrasts with the differential physical maturation of region-specific cerebral gray and white matter. Tentative paths of interpretation are proposed in the discussion.

Determinants of Processing Speed Trajectories among Middle Aged or Older Adults, and Their Association with Chronic Illnesses: The English Longitudinal Study of Aging

The aim of this study was to identify latent groups of similar trajectories in processing speed through aging, as well as factors that are associated with these trajectories. In the context of the Ageing Trajectories of Health: Longitudinal Opportunities and Synergies (ATHLOS) project, data from the English Longitudinal Study of Aging (ELSA) (n = 12099) were analyzed. Latent groups of similar trajectories in the processing scores as well as their predictors and covariates were investigated, using group-based trajectory models (GBTM). The coefficient estimates for potential group predictors correspond to parameters of multinomial logit functions that are integrated in the model. Potential predictors included sex, level of education, marital status, level of household wealth, level of physical activity, and history of smoking, while time-varying covariates included incidence of cardiovascular disease (CVD), diabetes mellitus, depressive symptoms, and sleep disturbances. Four trajectories were identified and named after their baseline scores and shapes: High (4.4%), Middle/Stable (31.5%), Low/Stable (44.5%), and Low Decline (19.6%). Female sex, higher levels of education, mild level of physical activity, having been married, and higher level of wealth were associated with a higher probability of belonging to any of the higher groups compared to the Low/Decline that was set as reference, while presence of CVD, diabetes mellitus, and depressive symptoms were associated with lower processing speed scores within most trajectories. All the aforementioned factors might be valid targets for interventions to reduce the burden of age-related cognitive impairment.

Neurophysiology of embedded response plans: age effects in action execution but not in feature integration from preadolescence to adulthood

Performing a goal-directed movement consists of a chain of complex preparatory mechanisms. Such planning especially requires integration (or binding) of various action features, a process that has been conceptualized in the "theory of event coding." Theoretical considerations and empirical research suggest that these processes are subject to developmental effects from adolescence to adulthood. The aim of the present study was to investigate age-related modulations in action feature binding processes and to shed light on underlying neurophysiological development from preadolescence to early adulthood. We examined a group of healthy participants (n = 61) between 10 and 30 yr of age, who performed a task that requires a series of bimanual response selections in an embedded paradigm. For an in-depth analysis of the underlying neural correlates, we applied EEG signal decomposition together with source localization analyses. Behavioral results across the whole group did not show binding effects in reaction times but in intraindividual response variability. From age 10 to 30 yr, there was a decrease in reaction times and reaction time variability but no age-related effect in action file binding. The latter were corroborated by Bayesian data analyses. On the brain level, the developmental effects on response selection were associated with activation modulations in the superior parietal cortex (BA7). The results show that mechanisms of action execution and speed, but not those of action feature binding, are subject to age-related changes between the age of 10 and 30 yr.NEW & NOTEWORTHY Different aspects of an action need to be integrated to allow smooth unfolding of behavior. We examine developmental effects in these processes and show that mechanisms of action execution and speed, but not those of action feature binding, are subject to age-related changes between the age of 10 and 30 yr.

Distraction of attention by novel sounds in children declines fast

New task-irrelevant sounds can distract attention. This study specifies the impact of stimulus novelty and of learning on attention control in three groups of children aged 6–7, 8, and 9–10 years and an adult control group. Participants (N = 179) were instructed to ignore a sound sequence including standard sounds and novel or repeated distractor sounds, while performing a visual categorization task. Distractor sounds impaired performance in children more than in adult controls, demonstrating the long-term development of attention control. Children, but not adults, were more distracted by novel than by repeated sounds, indicating increased sensitivity to novel information. Children, in particular younger children, were highly distracted during the first presentations of novel sounds compared to adults, while no age differences were observed for the last presentations. Results highlight the age-related impact of auditory novel information on attention and characterize the rapid development of attention control mechanisms as a function of age and exposure to irrelevant novel sounds.

Neuropsychological and neurophysiological correlates of fatigue in post-acute patients with neurological manifestations of COVID-19: Insights into a challenging symptom

More than half of patients who recover from COVID-19 experience fatigue. We studied fatigue using neuropsychological and neurophysiological investigations in post-COVID-19 patients and healthy subjects. Neuropsychological assessment included: Fatigue Severity Scale (FSS), Fatigue Rating Scale, Beck Depression Inventory, Apathy Evaluation Scale, cognitive tests, and computerized tasks. Neurophysiological examination was assessed before (PRE) and 2 min after (POST) a 1-min fatiguing isometric pinching task and included: maximum compound muscle action potential (CMAP) amplitude in first dorsal interosseous muscle (FDI) following ulnar nerve stimulation, resting motor threshold, motor evoked potential (MEP) amplitude and silent period (SP) duration in right FDI following transcranial magnetic stimulation of the left motor cortex. Maximum pinch strength was measured. Perceived exertion was assessed with the Borg-Category-Ratio scale. Patients manifested fatigue, apathy, executive deficits, impaired cognitive control, and reduction in global cognition. Perceived exertion was higher in patients. CMAP and MEP were smaller in patients both PRE and POST. CMAP did not change in either group from PRE to POST, while MEP amplitudes declined in controls POST. SP duration did not differ between groups PRE, increased in controls but decreased in patients POST. Patients' change of SP duration from PRE to POST was negatively correlated to FSS. Abnormal SP shortening and lack of MEP depression concur with a reduction in post-exhaustion corticomotor inhibition, suggesting a possible GABA_B-ergic dysfunction. This impairment might be related to the neuropsychological alterations. COVID-19-associated inflammation might lead to GABAergic impairment, possibly representing the basis of fatigue and explaining apathy and executive deficits.

The role of inhibitory control in the development of analogical reasoning: From general to specific

This study examined the role of inhibitory control in the development of analogical reasoning using inter-task priming paradigms. In Experiment 1, 25 seven-year-olds, 27 nine-year-olds, and 27 adults completed Stroop tasks, which activated general inhibitory control ability, before analogical reasoning tasks. Children and adults performed faster on analogical reasoning tasks when they were primed by Stroop tasks. This priming effect was found to be stronger in children than in adults. In Experiment 2, 25 seven-year-olds, 28 nine-year-olds, and 28 adults completed relative number matching tasks, a more task-relevant inhibitory control task, before analogical reasoning tasks. The children and adults performed faster on analogical reasoning tasks when primed by relative number matching tasks. The priming effect was greater in seven-year-olds than in nine-year-olds and was greater in nine-year-olds than in adults. Thus, inhibitory control, whether assessed with general or specific tasks, played a priming role in analogical reasoning.

Auditory and visual naming tests for children

Assessment of naming in children has been hampered by the use of tests that were developed, either to assess naming in adults or to assess related verbal functions in children. We developed comparable visual naming test (VNT) and auditory description naming (ANT) specifically for children. We collected normative data, not only for accuracy, typically the sole performance measure, but also for response time (RT) and reliance on phonemic cuing. The normative sample consisted of 200 typically developing children, ages 6-15, with 40 children per 2-year age group (6-7, 8-9, 10-11, 12-13, and 14-15). Children were tested individually by a trained examiner. Based on item analysis, naming tests were finalized at 36 items for ages 8-15 and 28 items for ages 6-7. Age-stratified normative data are provided for accuracy, mean RT, tip-of-the-tongues (i.e., delayed but accurate responses plus items named following phonemic cueing), and a summary score, which incorporates all performance measures. Internal and test-retest reliability coefficients for both tests were reasonable. Accuracy scores were high across age groups, indicating that item names were within the mental lexicon of most typically developing children. By contrast, time and cue-based scores improved with age, reflecting greater efficiency in word retrieval with development. These complementary auditory naming and visual naming tests for children address a longstanding clinical need, improving upon the current standard with respect to the sensitivity of performance measures and the addition of an auditory verbal component to the assessment of naming in children.

Prenatal exposure to organophosphorus pesticides and childhood neurodevelopmental phenotypes

Prenatal exposure to organophosphorus pesticides (OPs) has been associated with different neurodevelopmental outcomes across different cohorts. A phenotypic approach may address some of these differences by incorporating information across scales and accounting for the complex correlational structure of neurodevelopmental outcomes. Additionally, Bayesian hierarchical modeling can account for confounding by collinear co-exposures. We use this framework to examine associations between prenatal exposure to OPs and behavior, executive functioning, and IQ assessed at age 6-9 years in a cohort of 404 mother/infant pairs recruited during pregnancy. We derived phenotypes of neurodevelopment with a factor analysis, and estimated associations between OP metabolites and these phenotypes in Bayesian hierarchical models for exposure mixtures. We report seven factors: 1) Impulsivity and Externalizing, 2) Executive Functioning, 3) Internalizing, 4) Perceptual Reasoning, 5) Adaptability, 6) Processing Speed, and 7) Verbal Intelligence. These, along with the Working Memory Index, were standardized and scaled so that positive values reflected positive attributes and negative values represented adverse outcomes. Standardized dimethylphosphate metabolites were negatively associated with Internalizing factor scores (β^ - 0.13, 95% CI - 0.26, 0.00) but positively associated with Executive Functioning factor scores (β^ 0.18, 95% CI 0.04, 0.31). Standardized diethylphosphate metabolites were negatively associated with the Working Memory Index (β^ - 0.17, 95% CI - 0.33, - 0.03). Associations with factor scores were generally stronger and more precise than associations with individual instrument-specific items. Factor analysis of outcomes may provide some advantages in etiological studies of childhood neurodevelopment by incorporating information across scales to reduce dimensionality and improve precision.

The influence of pubertal maturation on antisaccade performance

Adolescence is a period characterized by continued improvements in inhibitory control, and this persisting immaturity is believed to interact with affective/motivational behavior to generate the impulsive and risk-taking behavior evidenced at this time. Puberty is a central event of adolescence that has been shown to influence affective/motivational behavior. However, despite plausible mechanisms by which puberty might influence inhibitory control, researchers have yet to test this possibility rigorously. Thus, we designed a study to examine the unique role of pubertal maturation, independent of age, in the development of inhibitory control. In order to minimize age-related variability while maximizing pubertal status variability, we recruited 78 participants (34 F) whose ages narrowly spanned the mean age of gonadarche for each sex (F: ages 11-13, M: ages 12-14). Two complementary measures were used to assess pubertal status: (1) circulating blood serum testosterone and estradiol levels reflecting internal manifestations of pubertal maturation, and (2) Tanner staging by a trained nurse reflecting pubertal maturation's external manifestations. Inhibitory control was assessed using the antisaccade task, and findings were adjusted for the potential effect of age. Results revealed no association between testosterone levels and error rates or response latencies in either sex. In girls, estradiol levels were not associated with error rates, but were associated with faster response latencies. There was similarly no association between Tanner status and error rates, although girls in more advanced pubertal stages showed faster response latencies. Power analyses indicate that findings of a lack of association did not reflect limited statistical power. Thus, in a study designed to isolate the effects of pubertal maturation independent of age, both external and internal indices of pubertal maturation converged to indicate that age-related improvements in cold antisaccade performance are independent of pubertal maturation.

Distraction by Novel and Pitch-Deviant Sounds in Children

The control of attention is an important part of our executive functions and enables us to focus on relevant information and to ignore irrelevant information. The ability to shield against distraction by task-irrelevant sounds is suggested to mature during school age. The present study investigated the developmental time course of distraction in three groups of children aged 7–10 years. Two different types of distractor sounds that have been frequently used in auditory attention research—novel environmental and pitch-deviant sounds—were presented within an oddball paradigm while children performed a visual categorization task. Reaction time measurements revealed decreasing distractor-related impairment with age. Novel environmental sounds impaired performance in the categorization task more than pitch-deviant sounds. The youngest children showed a pronounced decline of novel-related distraction effects throughout the experimental session. Such a significant decline as a result of practice was not observed in the pitch-deviant condition and not in older children. We observed no correlation between cross-modal distraction effects and performance in standardized tests of concentration and visual distraction. Results of the cross-modal distraction paradigm indicate that separate mechanisms underlying the processing of novel environmental and pitch-deviant sounds develop with different time courses and that these mechanisms develop considerably within a few years in middle childhood.

Theory of Mind and Executive Function: Working-Memory Capacity and Inhibitory Control as Predictors of False-Belief Task Performance

This study of the relationship between theory of mind and executive function examined whether on the false-belief task age differences between 3 and 5 years of age are related to development of working-memory capacity and inhibitory processes. 72 children completed tasks measuring false belief, working memory, and inhibition. Significant age effects were observed for false-belief and working-memory performance, as well as for the false-alarm and perseveration measures of inhibition. A simultaneous multiple linear regression specified the contribution of age, inhibition, and working memory to the prediction of false-belief performance. This model was significant, explaining a total of 36% of the variance. To examine the independent contributions of the working-memory and inhibition variables, after controlling for age, two hierarchical multiple linear regressions were conducted. These multiple regression analyses indicate that working memory and inhibition make small, overlapping contributions to false-belief performance after accounting for age, but that working memory, as measured in this study, is a somewhat better predictor of false-belief understanding than is inhibition.

Cognition and character traits as determinants of young children’s behaviour in traffic situations

Young children, 3 to 6 years’ old, were observed in two situations: (1) a traffic model, where they used dolls to enact the movements of two children on the way to and from day care; and (2) as they crossed a lightly trafficked, minor road in a situation analogous to that in the model. Atotal of 131 children participated. All were tested in the model situation (a), both on understanding of safety and safety devices and on road-crossing behaviour. The latter was seen as a task consisting of three components (i) using a zebra crossing, (ii) stopping at the curb, and (iii) looking for cars. Asubgroup of 47 children was tested on three character traits, activity, distraction, and impulsivity. Another subgroup of 45 children participated in the roadside situation (b). The results show that although both age and understanding were important predictors of appropriate behaviour in both traffic situations, the behaviour components were differentially related to these factors. Of the character traits, impulsivity was found to be reliably related to traffic behaviour.

Capturing the dynamics of response variability in the brain in ADHD

ADHD is characterized by increased intra-individual variability in response times during the performance of cognitive tasks. However, little is known about developmental changes in intra-individual variability, and how these changes relate to cognitive performance. Twenty subjects with ADHD aged 7-24 years and 20 age-matched, typically developing controls participated in an fMRI-scan while they performed a go-no-go task. We fit an ex-Gaussian distribution on the response distribution to objectively separate extremely slow responses, related to lapses of attention, from variability on fast responses. We assessed developmental changes in these intra-individual variability measures, and investigated their relation to no-go performance. Results show that the ex-Gaussian measures were better predictors of no-go performance than traditional measures of reaction time. Furthermore, we found between-group differences in the change in ex-Gaussian parameters with age, and their relation to task performance: subjects with ADHD showed age-related decreases in their variability on fast responses (sigma), but not in lapses of attention (tau), whereas control subjects showed a decrease in both measures of variability. For control subjects, but not subjects with ADHD, this age-related reduction in variability was predictive of task performance. This group difference was reflected in neural activation: for typically developing subjects, the age-related decrease in intra-individual variability on fast responses (sigma) predicted activity in the dorsal anterior cingulate gyrus (dACG), whereas for subjects with ADHD, activity in this region was related to improved no-go performance with age, but not to intra-individual variability. These data show that using more sophisticated measures of intra-individual variability allows the capturing of the dynamics of task performance and associated neural changes not permitted by more traditional measures.

The influence of executive functions on spatial biases varies during the lifespan

Many perceptual processes, such as language or face perception, are asymmetrically organised in the hemispheres already in childhood. These asymmetries induce behaviourally observable spatial biases in which the observer perceives stimuli in one of the hemispaces more efficiently or more frequently than in the other one. Another source for spatial biases is spatial attention which is also asymmetrically organised in the hemispheres. The bias induced by attention is directed towards the right side, which is clearly demonstrated by patients with neglect but also in lesser degree by healthy observers in cognitively loading situations. Recent findings indicate that children and older adults show stronger spatial biases than young adults. We discuss how the development of executive functions might contribute to the manifestation of spatial biases during the lifespan. We present a model in which the interaction between the asymmetrical perceptual processes, the age-related development of the lateralised spatial attention and the development of the executive functions influence spatial perceptual performance and in which the development and decline of the executive processes during the lifespan modify the spatial biases.

Neural correlates of inhibitory control and functional genetic variation in the dopamine D4 receptor gene

BACKGROUND

The dopamine D4 receptor gene (DRD4) has been implicated in psychiatric disorders in which deficits of self-regulation are a prominent feature (e.g., attention-deficit hyperactivity disorder and substance use disorders) and in dopamine D4 receptor insensitivity within prefrontal regions of the brain. Our hypothesis was that carriers of 7-repeats in the Variable Number of Tandem Repeats (VNTR) of DRD4 (7R+) would recruit prefrontal brain regions involved in successful inhibitory control to a lesser degree than non-carriers (7R-) and demonstrate less inhibitory control as confirmed by observation of locally reduced blood oxygenation level dependent (BOLD) % signal change and lower accuracy while performing "No-Go" trials of a Go/No-Go task.

METHODS

Participants (age=18, n=62, 33 females) were recruited from the general population of the St. Louis, Missouri region. Participants provided a blood or saliva sample for genotyping, completed drug and alcohol-related questionnaires and IQ testing, and performed a Go/No-Go task inside of a 3T fMRI scanner.

RESULTS

Go/No-Go task performance did not significantly differ between 7R+ and 7R- groups. Contrast of brain activity during correct "No-Go" trials with a non-target letter baseline revealed significant BOLD activation in a network of brain regions previously implicated in inhibitory control including bilateral dorsolateral prefrontal, inferior frontal, middle frontal, medial prefrontal, subcortical, parietal/temporal, and occipital/cerebellar brain regions. Mean BOLD % signal change during "No-Go" trials was significantly modulated by DRD4 genotype, with 7R+ showing a lower hemodynamic response than 7R- in right anterior prefrontal cortex/inferior frontal gyrus, left premotor cortex, and right occipital/cerebellar areas. Follow-up analyses suggested that 7-repeat status accounted for approximately 5-6% of the variance in the BOLD response during "No-Go" trials.

DISCUSSION

The DRD4 7-repeat allele may alter dopaminergic function in brain regions involved in inhibitory control. When individuals must inhibit a prepotent motor response, presence of this allele may account for 5-6% of the variance in BOLD signal in brain regions critically associated with inhibitory control, but its influence may be associated with a greater effect on brain than on behavior in 18-year-olds from the general population.

Temporal reward discounting in children, adolescents, and emerging adults during an experiential task

The goal of this study was to examine age effects on the ability/willingness to wait for large rewards in a real temporal reward discounting task from childhood to adulthood. Therefore, a real temporal discounting (TD) task was administered to children aged 6–12 (n = 39), adolescents aged 13–17 (n = 28), and young adults aged 18–19 (n = 55). Findings indicated that the cross-sectional development of TD followed a quadratic pattern across age groups, with adolescents choosing more often than children and adults to wait for the large delayed reward, resulting in reward-maximization. Various interpretations of this finding were offered, including a focus on reward maximization despite an immature ability to exert self-control, and flexible self-control which was high during this task as a result of strong motivation to maximize financial gains.

Previous reward decreases errors of commission on later 'No-Go' trials in children 4 to 12 years of age: evidence for a context monitoring account

Inhibitory control is widely hypothesized to be the cornerstone of executive function in childhood and the central deficit in a number of developmental disorders, including attention-deficit/hyperactivity disorder (ADHD). However, recent evidence from adults indicates that performance on response inhibition tasks may primarily reflect non-inhibitory attentional control (context monitoring) processes. Yet it may be that inhibition plays a more central role in childhood - a time when the architecture of cognitive processes might be more transparent due to wide variability in skill level. Here we directly test inhibitory and context monitoring explanations of task performance on a Go/No-Go task in a large group of children 4-12 years of age. We conclude that traditional inhibitory conceptualizations of task performance on the Go/No-Go task cannot account for our findings, calling into question evidence supporting a central role for inhibitory control in cognitive development or developmental psychopathology.

Cognitive processing and motor execution in the lexical decision task: a developmental study

We investigated lexical decision making in children and adults by analyzing spatiotemporal characteristics of responses involving a hand movement. Children's and adults' movement trajectories were assessed in three tasks: a lexical decision task (LDT), a pointing task that involved minimal cognitive processing, and a symbol task requiring a simple binary decision. Cognitive interference on motor performance was quantified by analyzing movement characteristics in the LDT and symbol task relative to the pointing task. Across age groups, movements in the LDT were less smooth, slower, and more strongly curved to the opposite response option, and these interference effects decreased steadily with age. Older children showed stronger interference effects than did adults, even though their reaction times were similar to adults' performance. No comparable effects were found in the symbol task, indicating that task characteristics such as response mapping and decision selection alone are not able to explain the developmental differences observed in the LDT. Our results indicate substantial overlap between cognitive processing and motor execution in the LDT in children that is not captured by computational models of visual word recognition and cognitive development.

Adolescents are more vulnerable to cocaine addiction: behavioral and electrophysiological evidence

In humans, adolescence is a period of heightened propensity to develop cocaine addiction. It is unknown whether this is attributable to greater access and exposure to cocaine at this age, or whether the adolescent brain is particularly vulnerable to the addictive properties of cocaine. Here, we subjected male adolescent (P42) and adult (∼P88) rats to a wide range of cocaine self-administration procedures. In addition, to determine whether behavioral differences are associated with developmental differences in dopaminergic activity, we examined and manipulated the activity of dopamine neurons. Relative to adults, adolescent rats took cocaine more readily, were more sensitive to lower doses, showed greater escalation of cocaine intake, and were less susceptible to increases in price (i.e., were more "inelastic"). In parallel, adolescents also showed elevated activity of ventral tegmental area dopamine neurons, a feature known to be associated with increased self-administration behavior. Pharmacological manipulation of dopamine D2 receptor function with quinpirole (agonist) or eticlopride (antagonist), to alter dopamine neuron activity, eliminated age differences in cocaine self-administration. These data suggest a causal relationship between behavioral and electrophysiological determinants of cocaine addiction liability. In conclusion, adolescents show behavioral and electrophysiological traits of heightened addiction liability.

Developmental effects of incentives on response inhibition

Inhibitory control and incentive processes underlie decision making, yet few studies have explicitly examined their interaction across development. Here, the effects of potential rewards and losses on inhibitory control in 64 adolescents (13- to 17-year-olds) and 42 young adults (18- to 29-year-olds) were examined using an incentivized antisaccade task. Notably, measures were implemented to minimize age-related differences in reward valuation and potentially confounding motivation effects. Incentives affected antisaccade metrics differently across the age groups. Younger adolescents generated more errors than adults on reward trials, but all groups performed well on loss trials. Adolescent saccade latencies also differed from adults across the range of reward trials. Overall, results suggest persistent immaturities in the integration of reward and inhibitory control processes across adolescence.

A GO intervention program for enhancing elementary school children's cognitive functions and control abilities of emotion and behavior: study protocol for a randomized controlled trial

BACKGROUND

Executive function is critical for children's healthy development. We propose an intervention program to enhance children's executive function using the game, GO. Many neuroimaging studies have revealed that playing GO is related to executive function. In addition, previous studies also revealed that executive function can be enhanced by training. We will perform a randomized controlled trial to investigate the effectiveness of a GO intervention group and a control group without intervention.

METHODS/DESIGN

35 elementary school children aged 8 to 10 were recruited from Edogawa elementary school in Tokyo, Japan. They will be randomized into two groups; either the 5-week GO intervention group or no-intervention control group. We will ask the participants of the intervention group to join the GO course which will be held once every week for five weeks (total: six times). In the GO course, the children will be taught GO by the GO masters of the Nihon Ki-in and enjoy it for an hour. Besides the course, the participants will perform GO problems about twenty minutes a day, three times a week during the intervention period. We will use the Stroop task, the digit span, the Raven's colored progressive matrices, the Span-board task, and the Behavioral inhibition/behavioral activation scale for the outcome measures. Outcomes will be measured at a baseline (Assessment 1) and 5 weeks after the intervention program started (Assessment 2). The intervention group will be compared with the control group using one-way analyses of covariance with the difference between Assessment 1 and Assessment 2 measures as dependent variables and pretest scores as covariates.

DISCUSSION

To our knowledge, this study will be the first RCT to investigate the efficacy of a GO intervention program for elementary school children. If this intervention is effective, we will be able to take the next steps in making an educational program to enhance children's executive function and other cognitive abilities using GO. In addition, we further will investigate the transfer effects of the GO intervention program through executive function. We also will investigate neuroplasticity with the GO intervention using neuroimaging.

Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?

Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) with performance on the delayed oculomotor response (DOR) task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects' ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than were controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower reaction times (RTs), greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than did controls. Greater variability in RT was associated with increased distraction on the DOR task, but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD.

Separating automatic and intentional inhibitory mechanisms of attention in adults with attention-deficit/hyperactivity disorder

Researchers in the cognitive sciences recognize a fundamental distinction between automatic and intentional mechanisms of inhibitory control. The use of eye-tracking tasks to assess selective attention has led to a better understanding of this distinction in specific populations, such as children with attention-deficit/hyperactivity disorder (ADHD). This study examined automatic and intentional inhibitory control mechanisms in adults with ADHD using a saccadic interference task and a delayed ocular response task. Thirty adults with ADHD were evaluated against 27 comparison adults on measures of inhibitory control. The delayed ocular response task showed that adults with ADHD were less able than comparison adults to inhibit a reflexive saccade toward the sudden appearance of a stimulus in the periphery. However, saccadic interference task performance showed that the ADHD group did not differ significantly from the comparison group on a measure of automatic inhibitory control. These findings suggest a dissociation between automatic and intentional inhibitory deficits in adults with ADHD.

The development of anticipatory cognitive control processes in task-switching: an ERP study in children, adolescents, and young adults

To investigate the development of advance task-set updating and reconfiguration, behavioral and event-related potential (ERP) data were recorded in children (9-10 years), adolescents (13-14 years), and young adults (20-27 years) in a cued task-switching paradigm. In pure blocks, the same task was repeated. In mixed blocks, comprised of stay and switch trials, two tasks were intermixed. Age differences were found for stay-pure performance (mixing costs) in the 600-ms but not in the 1200-ms cue-target interval (CTI). Children showed larger reaction time mixing costs than adults. The ERPs suggested that the larger costs were due to delayed anticipatory task-set updating in children. Switch-stay performance decrements (switch costs) were age-invariant in both CTIs. However, ERP data suggested that children reconfigured the task-set on some stay trials, rather than only on switch trials, suggesting the continued maturation of task-set reconfiguration processes.

Effects of response preparation on developmental improvements in inhibitory control

Studies in adults indicate that response preparation is crucial to inhibitory control, but it remains unclear whether preparation contributes to improvements in inhibitory control over the course of childhood and adolescence. In order to assess the role of response preparation in developmental improvements in inhibitory control, we parametrically manipulated the duration of the instruction period in an antisaccade (AS) task given to participants from ages 8 to 31 years. Regressions showing a protracted development of AS performance were consistent with existing research, and two novel findings emerged. First, all participants showed improved performance with increased preparation time, indicating that response preparation is crucial to inhibitory control at all stages of development. Preparatory processes did not deteriorate at even the longest preparatory period, indicating that the youngest participants were able to sustain preparation at even the longest interval. Second, developmental trajectories did not differ for different preparatory period lengths, highlighting that the processes supporting response preparation continue to mature in tandem with improvements in AS performance. Our findings suggest that developmental improvements are not simply due to an inhibitory system that is faster to engage but may also reflect qualitative changes in the processes engaged during the preparatory period.

Neurobehavioral evidence for changes in dopamine system activity during adolescence

Human adolescence has been characterized by increases in risk-taking, emotional lability, and deficient patterns of behavioral regulation. These behaviors have often been attributed to changes in brain structure that occur during this developmental period, notably alterations in gray and white matter that impact synaptic architecture in frontal, limbic, and striatal regions. In this review, we provide a rationale for considering that these behaviors may be due to changes in dopamine system activity, particularly overactivity, during adolescence relative to either childhood or adulthood. This rationale relies on animal data due to limitations in assessing neurochemical activity more directly in juveniles. Accordingly, we also present a strategy that incorporates molecular genetic techniques to infer the status of the underlying tone of the dopamine system across developmental groups. Implications for the understanding of adolescent behavioral development are discussed.

Real-time tracking of motor response activation and response competition in a Stroop task in young children: a lateralized readiness potential study

The ability to select an appropriate motor response by resolving competition among alternative responses plays a major role in cognitive performance. fMRI studies suggest that the development of this skill is related to the maturation of the frontal cortex that underlies the improvement of motor inhibition abilities. However, fMRI cannot characterize the temporal properties of motor response competition and motor activation in general. We studied the development of the time course of resolving motor response competition. To this end, we used the lateralized readiness potential (LRP), an ERP measure, for tracking correct and incorrect motor cortex activation in children in real time. Fourteen children and 14 adults took part in an animal-size Stroop task where they selected between two animals, presented simultaneously on the computer screen, which was larger in real life. In the incongruent condition, the LRP detected stronger and longer lasting incorrect response activation in children than in adults. LRP results could explain behavioral congruency effects, the generally longer RT in children than in adults and the larger congruency effect in children than in adults. In contrast, the peak latency of ERP waves, usually associated with stimulus processing speed, could explain neither of the above effects. We conclude that the development of resolving motor response competition, relying on motor inhibition skills, is a crucial factor in child development. Our study demonstrates that the LRP is an excellent tool for studying motor activation in children.

Immaturities in reward processing and its influence on inhibitory control in adolescence

The nature of immature reward processing and the influence of rewards on basic elements of cognitive control during adolescence are currently not well understood. Here, during functional magnetic resonance imaging, healthy adolescents and adults performed a modified antisaccade task in which trial-by-trial reward contingencies were manipulated. The use of a novel fast, event-related design enabled developmental differences in brain function underlying temporally distinct stages of reward processing and response inhibition to be assessed. Reward trials compared with neutral trials resulted in faster correct inhibitory responses across ages and in fewer inhibitory errors in adolescents. During reward trials, the blood oxygen level-dependent signal was attenuated in the ventral striatum in adolescents during cue assessment, then overactive during response preparation, suggesting limitations during adolescence in reward assessment and heightened reactivity in anticipation of reward compared with adults. Importantly, heightened activity in the frontal cortex along the precentral sulcus was also observed in adolescents during reward-trial response preparation, suggesting reward modulation of oculomotor control regions supporting correct inhibitory responding. Collectively, this work characterizes specific immaturities in adolescent brain systems that support reward processing and describes the influence of reward on inhibitory control. In sum, our findings suggest mechanisms that may underlie adolescents' vulnerability to poor decision-making and risk-taking behavior.

Using the antisaccade task to investigate the relationship between the development of inhibition and the development of intelligence

A number of authors have proposed models of cognitive development that explain improvements in intelligence over the course of childhood via changes in the efficiency of inhibitory processes (Anderson, 2001; Bjorklund & Harnishfeger, 1990; Dempster, 1991, 1992; Dempster & Corkill, 1999a; Harnishfeger, 1995; Harnishfeger & Bjorklund, 1993). A review of the literature reveals little empirical support for the thesis. This is largely due to a failure to distinguish between age-related and non-age-related changes in both inhibitory ability and intelligence. Empirical evidence is presented from a developmental study employing the antisaccade task to provide support for the role of inhibitory processes in the development of intelligence. Additionally, a case is made for a functional difference underlying antisaccade errors that are subsequently corrected and those that remain uncorrected.

Age-related differences in reaction time task performance in young children

Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a "global" mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59 6-year-olds, and 35 adults from Russia. Using the regression approach pioneered by Brinley and the transformation method proposed by Madden and colleagues and Ridderinkhoff and van der Molen, age-related differences in processing speed differed among RT tasks with varying demands. In particular, RTs differed between children and adults on tasks that required response suppression, discrimination of color or spatial orientation, reversal of contingencies of previously learned stimulus-response rules, and greater stimulus-response complexity. Relative costs of these RT task differences were larger than predicted by the global difference hypothesis except for response suppression. Among young children, age-related differences larger than predicted by the global difference hypothesis were evident when tasks required color or spatial orientation discrimination and stimulus-response rule complexity, but not for response suppression or reversal of stimulus-response contingencies. Process-specific, age-related differences in processing speed that support heterochronicity of brain development during childhood were revealed.

Neurodevelopment and executive function in autism

Autism is a neurodevelopmental disorder characterized by social and communication deficits, and repetitive behavior. Studies investigating the integrity of brain systems in autism suggest a wide range of gray and white matter abnormalities that are present early in life and change with development. These abnormalities predominantly affect association areas and undermine functional integration. Executive function, which has a protracted development into adolescence and reflects the integration of complex widely distributed brain function, is also affected in autism. Evidence from studies probing response inhibition and working memory indicate impairments in these core components of executive function, as well as compensatory mechanisms that permit normative function in autism. Studies also demonstrate age-related improvements in executive function from childhood to adolescence in autism, indicating the presence of plasticity and suggesting a prolonged window for effective treatment. Despite developmental gains, mature executive functioning is limited in autism, reflecting abnormalities in wide-spread brain networks that may lead to impaired processing of complex information across all domains.

Cognitive control of involuntary attention and distraction in children and adolescents

The present study focused on the control of involuntary attentional orienting and distraction in children (6-8, 10-12 years) and adolescents (17-18 years). In an auditory distraction paradigm, pitch deviants interspersed in a sequence of standard sounds were presented. In the predictable condition, the type of sound (standard or deviant) was announced by a preceding visual cue. In the unpredictable condition, the cue was not informative with respect to the type of sound. Subjects performed a sound duration discrimination task and were instructed to attend the cues in order to avoid distraction. In the unpredictable condition, regular behavioral and ERP effects of change detection (Mismatch Negativity), attentional orienting (P3a) and distraction (prolonged reaction times) were observed. In the predictable condition, no modulation of Mismatch Negativity amplitude was observed, whereas the amplitude of P3a and reaction time prolongations in deviant trials were reduced in all age groups. Results suggest that even young children are able to voluntarily control involuntary attentional orienting and behavioral distraction. However, significant age effects were observed for the level of behavioral distraction and the selective utilization of the visual cues (reflected by P3b).

Maturation of executive function in autism

BACKGROUND

Executive dysfunction has been reported at different ages in autism. It is not clear however, when this impairment emerges or how its expression is affected by development.

METHODS

61 non-mentally retarded autism participants (AUT) and 61 age, gender, and IQ matched typically developing participants (CON) were assessed with two oculomotor executive function tasks, the oculomotor delayed response task (ODR) and the antisaccade task (AS), as well as a visually-guided saccade sensorimotor task (VGS).

RESULTS

The AUT group demonstrated impairments in response inhibition and spatial working memory at all ages tested. Developmental improvements in speed of sensorimotor processing and voluntary response inhibition were similar in both groups indicating sparing of some attentional control of behavior. Developmental progression in the speed of initiating a cognitive plan and maintaining information on line over time, however, was impaired in the AUT group indicating abnormal development of working memory.

CONCLUSIONS

These results indicate that while executive dysfunction is present throughout development, there is evidence for both typical and atypical developmental progression of executive functions in autism. The plasticity suggested by the developmental improvements may have implications regarding appropriate developmental epochs and types of interventions aimed at enhancing cognitive capacities in individuals with autism.

Cognitive processes in the development of TOL performance

Components of executive function continue to develop through adolescence. There is limited knowledge of how these cognitive components impact complex cognitive function requiring their integration. This study examines the development of response planning, a complex cognitive function, and the contributions of selected cognitive processes, including speed of processing, response inhibition, and working memory to its development. We tested 100 healthy 8-30 year old individuals with a computerized version to the Tower of London (TOL) task and cognitive oculomotor tests including the visually guided saccade, oculomotor delayed response, and antisaccade tasks. Speed of processing, response inhibition, working memory, and TOL performance all demonstrated maturation in adolescence. While all processes were correlated with the development of TOL performance, antisaccade performance showed the strongest association indicating an important role for response inhibition in planning. These results indicate that the development of converging cognitive processes in adolescence, including response inhibition and working memory, support response planning and may serve as a model for the development of performance in other complex problem solving tasks.

What have we learned about cognitive development from neuroimaging?

Changes in many domains of cognition occur with development. In this paper, we discuss neuroimaging approaches to understanding these changes at a neural level. We highlight how modern imaging methods such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are being used to examine how cognitive development is supported by the maturation of the brain. Some reports suggest developmental changes in patterns of brain activity appear to involve a shift from diffuse to more focal activation, likely representing a fine-tuning of relevant neural systems with experience. One of the challenges in investigating the interplay between cognitive development and maturation of the brain is to separate the contributions of neural changes specific to development and learning. Examples are given from the developmental neuroimaging literature. The focus is on the development of cognitive control, as the protracted developmental course of this ability into adolescence raises key issues. Finally, the relevance of normative studies for understanding neural and cognitive changes in developmental disorders is discussed.

Sequential effects on speeded information processing: A developmental study

Two experiments were performed to assess age-related changes in sequential effects on choice reaction time (RT). Sequential effects portray the influence of previous trials on the RT to the current stimulus. In Experiment 1, three age groups (7-9, 10-12, and 18-25 years) performed a spatially compatible choice task, with response-to-stimulus intervals (RSIs) of 50 and 500 ms varied between trial blocks. In Experiment 2, three age groups (7-9, 15-16, and 18-25 years) performed the task with spatial stimulus-response (S-R) mappings (compatible versus incompatible) varied between participants. For adults, the experiments yielded a pattern of sequential effects suggestive of "automatic facilitation" (i.e., a first-order repetition effect and a higher order benefit-only pattern for short RSIs) and "subjective expectancy" (i.e., a first-order alternation effect and a higher order cost-benefit pattern for long RSIs). Automatic facilitation was more pronounced for incompatible responses than for compatible responses. Both experiments showed the anticipated decrease in automatic facilitation with advancing age. Finally, the first-order alternation effect showed the predicted age-related increase, but the cost-benefit pattern revealed an opposite trend, suggesting that the first-order and higher order indexes of subjective expectancy may relate to dissociable mechanisms.

Delta Plots in the Study of Individual Differences: New Tools Reveal Response Inhibition Deficits in AD/HD That Are Eliminated by Methylphenidate Treatment

The authors highlight the utility of distribution-analytical techniques in the study of individual differences and clinical disorders. Cognitive deficits associated with attention-deficit/hyperactivity disorder (AD/HD) were examined by using delta-plot analyses of performance data (reaction time and accuracy) obtained through the use of a prototypical conflict task, the Eriksen flanker task. In 20 children with AD/HD (compared with matched control participants), overall performance measures indicated a marginal performance deficit. Delta-plot analyses indicated that performance deficits associated with AD/HD involve response inhibition but not automatic response activation. In a within-subjects titration study, the response inhibition deficit was eliminated by methylphenidate treatment, but these effects were highly dose specific. The beneficial effect of methylphenidate was clarified further after correcting for inter-individual variation in sensitivity to medicine dosage.

Age-related changes in the efficiency of cognitive processing across the life span

The global-speed and the specific-gain/loss hypotheses have been dominant theoretical frameworks in the recent literature on cognitive development and aging. Few attempts have been made to explicitly assess the predictive power of the two frameworks against each other. We evaluated the extent to which age changes in performance in executive function tasks (involving response selection, response suppression, working memory, and adaptive control) depend on age-related changes in global information-processing speed. Our sample consisted of children, adolescents, adults and seniors. Analysis of covariance and structural equation modeling revealed a mixed pattern of results. Controlling for global speed removed the child vs. adult differences in the speed of responding on the executive function tasks but the senior vs. adult differences remained. This mixed pattern of findings was interpreted to suggest that the effects of advancing age on the speed of responding are mediated by a global mechanism during childhood but during senescence the efficiency of executive functioning seems particularly vulnerable to the effects of age.

Maturation of Cognitive Processes From Late Childhood to Adulthood

To characterize cognitive maturation through adolescence, processing speed, voluntary response suppression, and spatial working memory were measured in 8- to 30-year-old (N = 245) healthy participants using oculomotor tasks. Development progressed with a steep initial improvement in performance followed by stabilization in adolescence. Adult-level mature performance began at approximately 15, 14, and 19 years of age for processing speed, response inhibition, and working memory, respectively. Although processes developed independently, processing speed influenced the development of working memory whereas the development of response suppression and working memory were interdependent. These results indicate that processing speed, voluntary response suppression, and working memory mature through late childhood and into adolescence. How brain maturation specific to adolescence may support cognitive maturation is discussed.