The development of spatial working memory abilities

The Influence of Memory on Visual Perception in Infants, Children, and Adults

Perception is not an independent, in-the-moment event. Instead, perceiving involves integrating prior expectations with current observations. How does this ability develop from infancy through adulthood? We examined how prior visual experience shapes visual perception in infants, children, and adults. Using an identical task across age groups, we exposed participants to pairs of colorful stimuli and implicitly measured their ability to discriminate relative saturation levels. Results showed that adult participants were biased by previously experienced exemplars, and exhibited weakened in-the-moment discrimination between different levels of saturation. In contrast, infants and children showed less influence of memory in their perception, and they actually outperformed adults in discriminating between current levels of saturation. Our findings suggest that as humans develop, their perception relies more on prior experience and less on current observation.

Ontogeny of working memory and behavioural flexibility in the free movement pattern (FMP) Y-maze in zebrafish

The acquisition of executive skills such as working memory, decision-making and adaptive responding occur at different stages of central nervous system development. Zebrafish (Danio rerio) are increasingly used in behavioural neuroscience for complex behavioural tasks, and there is a critical need to understand the ontogeny of their executive functions. Zebrafish across developmental stages (4, 7, 14, 30 and 90 days post fertilisation (dpf)), were assessed to track development of working memory (WM) and behavioural flexibility (BF) using the free movement pattern Y-maze (FMP Y-maze). Several differences in both WM and BF were identified during the transition from yolk-dependent to independent feeding. Specifically, WM is evident in all age groups, even from 4 dpf. However, BF is not developed until larvae start free feeding, and show significant improvement thereafter, with young adults (90 dpf) demonstrating the most well-defined BF. We demonstrate, for the first time, objective WM processes in 4 dpf zebrafish larvae. This suggests that those wishing to study WM in zebrafish may be able to do so from 4 dpf, thus drastically increasing throughput. In addition, we show that zebrafish follow distinct stages of cognitive development and age-related changes during the early developmental period. Finally, our findings indicate distinct WM and BF mechanisms, which may be useful to study for translational purposes.

Adolescent-specific memory effects: evidence from working memory, immediate and long-term recognition memory performance in 8-30 yr olds

Working memory and recognition memory develop across adolescence, but the relationship between them is not fully understood. We investigated associations between n-back task performance and subsequent recognition memory in a community sample (8-30 yr, n = 150) using tasks from the Adolescent Brain Cognitive Development Study (ABCD Study) to cross-sectionally assess memory in an age range that will be sampled longitudinally. We added a 24-h delay condition to assess long-term recognition. Overall working memory, immediate and long-term recognition performance peaked in adolescence. Age effects in recognition memory varied by items (old targets, old distractors, and new items) and delay (0 and 24 h). For immediate recognition, accuracy was higher for targets and new items than for distractors, with accuracy for targets peaking in adulthood and accuracy for new items peaking during adolescence. For long-term recognition, adolescents' accuracy was higher for targets than distractors, while adults showed similarly high accuracy for targets and distractors and children showed low accuracy for both. This pattern appeared to be specific to recognition of items from the high working memory load condition. The results suggest that working memory may facilitate long-term recognition of task-relevant over irrelevant items and may benefit the detection of new information during adolescence.

Effects of facial expression and gaze interaction on brain dynamics during a working memory task in preschool children

Executive functioning in preschool children is important for building social relationships during the early stages of development. We investigated the brain dynamics of preschool children during an attention-shifting task involving congruent and incongruent gaze directions in emotional facial expressions (neutral, angry, and happy faces). Ignoring distracting stimuli (gaze direction and expression), participants (17 preschool children and 17 young adults) were required to detect and memorize the location (left or right) of a target symbol as a simple working memory task (i.e., no general priming paradigm in which a target appears after a cue stimulus). For the preschool children, the frontal late positive response and the central and parietal P3 responses increased for angry faces. In addition, a parietal midline α (Pmα) power to change attention levels decreased mainly during the encoding of a target for angry faces, possibly causing an association of no congruency effect on reaction times (i.e., no faster response in the congruent than incongruent gaze condition). For the adults, parietal P3 response and frontal midline θ (Fmθ) power increased mainly during the encoding period for incongruent gaze shifts in happy faces. The Pmα power for happy faces decreased for incongruent gaze during the encoding period and increased for congruent gaze during the first retention period. These results suggest that adults can quickly shift attention to a target in happy faces, sufficiently allocating attentional resources to ignore incongruent gazes and detect a target, which can attenuate a congruency effect on reaction times. By contrast, possibly because of underdeveloped brain activity, preschool children did not show the happy face superiority effect and they may be more responsive to angry faces. These observations imply a crucial key point to build better relationships between developing preschoolers and their parents and educators, incorporating nonverbal communication into social and emotional learning.

Negative Effects of Embodiment in a Visuo-Spatial Working Memory Task in Children, Young Adults, and Older Adults

Studies examining the effect of embodied cognition have shown that linking one's body movements to a cognitive task can enhance performance. The current study investigated whether concurrent walking while encoding or recalling spatial information improves working memory performance, and whether 10-year-old children, young adults, or older adults (M age = 72 years) are affected differently by embodiment. The goal of the Spatial Memory Task was to encode and recall sequences of increasing length by reproducing positions of target fields in the correct order. The nine targets were positioned in a random configuration on a large square carpet (2.5 m × 2.5 m). During encoding and recall, participants either did not move, or they walked into the target fields. In a within-subjects design, all possible combinations of encoding and recall conditions were tested in counterbalanced order. Contrary to our predictions, moving particularly impaired encoding, but also recall. These negative effects were present in all age groups, but older adults' memory was hampered even more strongly by walking during encoding and recall. Our results indicate that embodiment may not help people to memorize spatial information, but can create a dual-task situation instead.

Multimodal indicators of risk for and consequences of substance use disorders: Executive functions and trait disconstraint assessed from preadolescence into early adulthood

Risk for substance use disorders (SUDs) is hypothesized to include behavioral disinhibition, a genetically mediated inability to inhibit or regulate behavior given task demands or motivational drives. In the present study, we examined developmental trajectories of multiple indicators of behavioral disinhibition assessed from preadolescence into early adulthood among individuals with versus without alcohol, tobacco, and cannabis use disorders. Participants were a population-based sample of 1512 male and female twins from the Minnesota Twin Family Study, prospectively assessed at ages 11, 14, 17, 20, and 24. Multimodal indicators of behavioral disinhibition included measures of executive function (visuospatial working memory accuracy, antisaccade task performance) and mother- and self-reported trait disconstraint. Multilevel modeling analyses that accounted for the repeated measures and nested nature of the twin family data were used to examine premorbid (age 11) indicators of executive function and trait disconstraint prior to the onset of any SUD symptoms, as well as changes from preadolescence into early adulthood (ages 11 to 24). Premorbid deviations evident at age 11 among individuals who subsequently developed SUDs included poorer performance on the visuospatial working memory test and higher levels of trait disconstraint. In addition, individuals with SUDs did not demonstrate developmentally normative improvements in inhibitory control (i.e., antisaccade performance did not improve) or in their levels of trait disconstraint. We conclude that these deviations in both neurocognitive and dispositional correlates of behavioral disinhibition precede onset of SUDs and may confer risk for their development, and in addition, problematic substance use may exacerbate preexisting deviations and interfere with normative developmental trajectories of executive function and trait disconstraint, with deleterious consequences for functioning.

Longitudinal development of visual working memory precision in childhood and early adolescence

Visual working memory (VWM) is the ability to hold in mind visual information for brief periods of time. The current study investigated VWM precision development longitudinally. Participants (N = 40, aged 7-11 years) completed delayed reproduction sequential VWM tasks at baseline and two years later. Results show age-related improvement in recall precision on both 1-item and 3-item VWM tasks, suggesting development during childhood and early adolescence in the resolution with which both single and multiple items are stored in VWM. Probabilistic modelling of response distribution data suggests age-related improvement in precision is attributable to a specific decrease in the variability (noisiness) of stored feature representations. This highlights a novel developmental mechanism which may underlie longitudinal improvement in VWM performance, crucially without invoking improvement in the number of items that can be stored. VWM precision provides a sensitive metric with which to track developmental changes longitudinally, shedding light on underlying cognitive mechanisms.

The neurodevelopmental differences of increasing verbal working memory demand in children and adults

Working memory (WM) – temporary storage and manipulation of information in the mind – is a key component of cognitive maturation, and structural brain changes throughout development are associated with refinements in WM. Recent functional neuroimaging studies have shown that there is greater activation in prefrontal and parietal brain regions with increasing age, with adults showing more refined, localized patterns of activations. However, few studies have investigated the neural basis of verbal WM development, as the majority of reports examine visuo-spatial WM.

We used fMRI and a 1-back verbal WM task with six levels of difficulty to examine the neurodevelopmental changes in WM function in 40 participants, twenty-four children (ages 9–15 yr) and sixteen young adults (ages 20–25 yr). Children and adults both demonstrated an opposing system of cognitive processes with increasing cognitive demand, where areas related to WM (frontal and parietal regions) increased in activity, and areas associated with the default mode network decreased in activity. Although there were many similarities in the neural activation patterns associated with increasing verbal WM capacity in children and adults, significant changes in the fMRI responses were seen with age. Adults showed greater load-dependent changes than children in WM in the bilateral superior parietal gyri, inferior frontal and left middle frontal gyri and right cerebellum. Compared to children, adults also showed greater decreasing activation across WM load in the bilateral anterior cingulate, anterior medial prefrontal gyrus, right superior lateral temporal gyrus and left posterior cingulate. These results demonstrate that while children and adults activate similar neural networks in response to verbal WM tasks, the extent to which they rely on these areas in response to increasing cognitive load evolves between childhood and adulthood.

Hemispheric lateralization of verbal and spatial working memory during adolescence

Adult functional magnetic resonance imaging (fMRI) literature suggests that a left-right hemispheric dissociation may exist between verbal and spatial working memory (WM), respectively. However, investigation of this type has been obscured by incomparable verbal and spatial WM tasks and/or visual inspection at arbitrary thresholds as means to assess lateralization. Furthermore, it is unclear whether this hemispheric lateralization is present during adolescence, a time in which WM skills are improving, and whether there is a developmental association with laterality of brain functioning. This study used comparable verbal and spatial WM n-back tasks during fMRI and a bootstrap analysis approach to calculate lateralization indices (LIs) across several thresholds to examine the potential of a left-right WM hemispheric dissociation in healthy adolescents. We found significant left hemispheric lateralization for verbal WM, most notably in the frontal and parietal lobes, as well as right hemisphere lateralization for spatial WM, seen in frontal and temporal cortices. Although no significant relationships were observed between LI and age or LI and performance, significant age-related patterns of brain activity were demonstrated during both verbal and spatial WM. Specifically, increased adolescent age was associated with less activity in the default mode brain network during verbal WM. In contrast, increased adolescent age was associated with greater activity in task-positive posterior parietal cortex during spatial working memory. Our findings highlight the importance of utilizing non-biased statistical methods and comparable tasks for determining patterns of functional lateralization. Our findings also suggest that, while a left-right hemispheric dissociation of verbal and spatial WM is apparent by early adolescence, age-related changes in functional activation during WM are also present.

Associations between white matter microstructure and infants' working memory

Working memory emerges in infancy and plays a privileged role in subsequent adaptive cognitive development. The neural networks important for the development of working memory during infancy remain unknown. We used diffusion tensor imaging (DTI) and deterministic fiber tracking to characterize the microstructure of white matter fiber bundles hypothesized to support working memory in 12-month-old infants (n=73). Here we show robust associations between infants' visuospatial working memory performance and microstructural characteristics of widespread white matter. Significant associations were found for white matter tracts that connect brain regions known to support working memory in older children and adults (genu, anterior and superior thalamic radiations, anterior cingulum, arcuate fasciculus, and the temporal-parietal segment). Better working memory scores were associated with higher FA and lower RD values in these selected white matter tracts. These tract-specific brain-behavior relationships accounted for a significant amount of individual variation above and beyond infants' gestational age and developmental level, as measured with the Mullen Scales of Early Learning. Working memory was not associated with global measures of brain volume, as expected, and few associations were found between working memory and control white matter tracts. To our knowledge, this study is among the first demonstrations of brain-behavior associations in infants using quantitative tractography. The ability to characterize subtle individual differences in infant brain development associated with complex cognitive functions holds promise for improving our understanding of normative development, biomarkers of risk, experience-dependent learning and neuro-cognitive periods of developmental plasticity.

Speed of processing, anticipation, inhibition and working memory in bilinguals

Literature on the so-called bilingual advantage is directed towards the investigation of whether the mastering of two languages fosters cognitive skills in the non-verbal domain. The present study aimed to evaluate whether the bilingual advantage in non-verbal skills could be best defined as domain-general or domain-specific, and, in the latter case, at identifying the basic cognitive skills involved. Bilingual and monolingual participants were divided into two different age groups (children, youths) and were tested on a battery of elementary cognitive tasks which included a choice reaction time task, a go/no-go task, two working memory tasks (numbers and symbols) and an anticipation task. Bilingual and monolingual children did not differ from each other except for the anticipation task, where bilinguals were found to be faster and more accurate than monolinguals. These findings suggest that anticipation, which has received little attention to date, is an important cognitive domain which needs to be evaluated to a greater extent both in bilingual and monolingual participants.

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.

White matter development in adolescence: a DTI study

Adolescence is a unique period of physical and cognitive development that includes concurrent pubertal changes and sex-based vulnerabilities. While diffusion tensor imaging (DTI) studies show white matter maturation throughout the lifespan, the state of white matter integrity specific to adolescence is not well understood as are the contributions of puberty and sex. We performed whole-brain DTI studies of 114 children, adolescents, and adults to identify age-related changes in white matter integrity that characterize adolescence. A distinct set of regions across the brain were found to have decreasing radial diffusivity across age groups. Region of interest analyses revealed that maturation was attained by adolescence in broadly distributed association and projection fibers, including those supporting cortical and brain stem integration that may underlie known enhancements in reaction time during this period. Maturation after adolescence included association and projection tracts, including prefrontal-striatal connections, known to support top-down executive control of behavior and interhemispheric connectivity. Maturation proceeded in parallel with pubertal changes to the postpubertal stage, suggesting hormonal influences on white matter development. Females showed earlier maturation of white matter integrity compared with males. Together, these findings suggest that white matter connectivity supporting executive control of behavior is still immature in adolescence.

The maturation of incentive processing and cognitive control

Understanding how immaturities in the reward system affect decision-making can inform us on adolescent vulnerabilities to risk-taking, which is a primary contributor to mortality and substance abuse in this age group. In this paper, we review the literature characterizing the neurodevelopment of reward and cognitive control and propose a model for adolescent reward processing. While the functional neuroanatomy of the mature reward system has been well-delineated, adolescent reward processing is just beginning to be understood. Results indicate that adolescents relative to adults demonstrate decreased anticipatory processing and assessment of risk, but an increased consummatory response. Such differences could result in suboptimal representations of reward valence and value and bias adolescent decision-making. These functional differences in reward processing occur in parallel with on-going structural and pharmacological maturation in the adolescent brain. In addition to limitations in incentive processing, basic cognitive control abilities, including working memory and inhibitory control, continue to mature during adolescence. Consequently, adolescents may be limited, relative to adults, in their abilities to inhibit impulsive behaviors and reliably hold 'on-line' comparisons of potential rewards/punishments during decision-making.

Development of eye-movement control

Cognitive control of behavior continues to improve through adolescence in parallel with important brain maturational processes including synaptic pruning and myelination, which allow for efficient neuronal computations and the functional integration of widely distributed circuitries supporting top-down control of behavior. This is also a time when psychiatric disorders, such as schizophrenia and mood disorders, emerge reflecting a particularly vulnerability to impairments in development during adolescence. Oculomotor studies provide a unique neuroscientific approach to make precise associations between cognitive control and brain circuitry during development that can inform us of impaired systems in psychopathology. In this review, we first describe the development of pursuit, fixation, and visually-guided saccadic eye movements, which collectively indicate early maturation of basic sensorimotor processes supporting reflexive, exogenously-driven eye movements. We then describe the literature on the development of the cognitive control of eye movements as reflected in the ability to inhibit a prepotent eye movement in the antisaccade task, as well as making an eye movement guided by on-line spatial information in working memory in the oculomotor delayed response task. Results indicate that the ability to make eye movements in a voluntary fashion driven by endogenous plans shows a protracted development into adolescence. Characterizing the transition through adolescence to adult-level cognitive control of behavior can inform models aimed at understanding the neurodevelopmental basis of psychiatric disorders.

Development of working memory maintenance

The neural circuitry supporting mature visual spatial working memory (VSWM) has been well delineated in nonhuman primates and in human adults. However, we still have limited understanding about developmental change through adolescence in this network. We present results from a fast event-related functional MRI (fMRI) study aimed at characterizing developmental changes in brain mechanisms supporting VSWM across different delay periods. Forty-three healthy subjects (17 adults, 18-30 yr; 13 adolescents, 13-17 yr; 13 children, 8-12 yr) were scanned as they performed an oculomotor delayed response (ODR) task with short (2.5 s) and long (10 s) delay period trials. Results showed that all age groups recruited a common network of regions to support both delay trials, including frontal, parietal, and temporal regions, indicative of a core circuitry needed to perform the task. Several age-related differences were found in the recruitment of regions, supporting short delay trials, including fronto-caudal areas, which could contribute to known differences in initial memory-guided saccade precision. To support extended delay trials, adults primarily recruited additional posterior parietal cortex (PPC), whereas children and adolescents recruited a considerably more extensive distributed circuitry. Our findings indicate that brain processes supporting basic aspects of working memory across cortex are established by childhood. We also find evidence for continued immaturities in systems supporting working memory precision, reflected by differences in the circuitry recruited by children and by continued refinement of fronto-insular-temporal regions recruited by adolescents. Taken together, these results suggest distinct developmental changes in the circuitry supporting visual spatial working memory.

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.

fMRI studies of eye movement control: investigating the interaction of cognitive and sensorimotor brain systems

Functional neuroimaging studies of eye movement control have been a useful approach for investigating the interaction of cognitive and sensorimotor brain systems. Building on unit recording studies of behaving nonhuman primates and clinical studies of patients with a focal brain lesion, functional neuroimaging studies have elucidated a pattern of hierarchical organization through which prefrontal and premotor systems interact with sensorimotor systems to support context-dependent adaptive behavior. Studies of antisaccades, memory-guided saccades, and predictive saccades have helped clarify how cognitive brain systems support contextually guided and internally generated action. The use of cognitive and sensorimotor eye movement paradigms is being used to develop a better understanding of life span changes in neurocognitive systems from childhood to late life, and about behavioral and systems-level brain abnormalities in neuropsychiatric disorders.

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.

Threat-related attentional bias in anxious youth: a review

The research literature suggests that children and adolescents suffering from anxiety disorders experience cognitive distortions that magnify their perceived level of threat in the environment. Of these distortions, an attentional bias toward threat-related information has received the most theoretical and empirical consideration. A large volume of research suggests that anxiety-disordered youth selectively allocate their attention toward threat-related information. The present review critically examines this research and highlights several issues relevant to the study of threat-related attentional bias in youth, including the influences of temperament, trait anxiety, and state anxiety on threat-related attentional bias. It furthermore identifies the need for developmental and methodological considerations and recommends directions for research.

Brain Basis of Developmental Change in Visuospatial Working Memory

Although brain changes associated with the acquisition of cognitive abilities in early childhood involve increasing localized specialization, little is known about the brain changes associated with the refinement of existing cognitive abilities that reach maturity in adolescence. The goal of this study was to investigate developmental changes in functional brain circuitry that support improvements in visuospatial working memory from childhood to adulthood. We tested thirty 8- to 47-year-olds in an oculomotor delayed response task. Developmental transitions in brain circuitry included both quantitative changes in the recruitment of necessary working memory regions and qualitative changes in the specific regions recruited into the functional working memory circuitry. Children recruited limited activation from core working memory regions (dorsal lateral prefrontal cortex [DLPFC] and parietal regions) and relied primarily on ventromedial regions (caudate nucleus and anterior insula). With adolescence emerged a more diffuse network (DLPFC, anterior cingulate, posterior parietal, anterior insula) that included the functional integration of premotor response preparation and execution circuitry. Finally, adults recruited the most specialized network of localized regions together with additional performance-enhancing regions, including left-lateralized DLPFC, ventrolateral prefrontal cortex, and supramarginal gyrus. These results suggest that the maturation of adult-level cognition involves a combination of increasing localization within necessary regions and their integration with performance-enhancing regions.

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.

The development of nonverbal working memory and executive control processes in adolescents

The prefrontal cortex modulates executive control processes and structurally matures throughout adolescence. Consistent with these events, prefrontal functions that demand high levels of executive control may mature later than those that require working memory but decreased control. To test this hypothesis, adolescents (9 to 20 years old) completed nonverbal working memory tasks with varying levels of executive demands. Findings suggest that recall-guided action for single units of spatial information develops until 11 to 12 years. The ability to maintain and manipulate multiple spatial units develops until 13 to 15 years. Strategic self-organization develops until ages 16 to 17 years. Recognition memory did not appear to develop over this age range. Implications for prefrontal cortex organization by level of processing are discussed.

fMRI reveals alteration of spatial working memory networks across adolescence

Recent studies have described neuromaturation and cognitive development across the lifespan, yet few neuroimaging studies have investigated task-related alterations in brain activity during adolescence. We used functional magnetic resonance imaging (fMRI) to examine brain response to a spatial working memory (SWM) task in 49 typically developing adolescents (25 females and 24 males; ages 12-17). No gender or age differences were found for task performance during SWM. However, age was positively associated with SWM brain response in left prefrontal and bilateral inferior posterior parietal regions. Age was negatively associated with SWM activation in bilateral superior parietal cortex. Gender was significantly associated with SWM response; females demonstrated diminished anterior cingulate activation and males demonstrated greater response in frontopolar cortex than females. Our findings indicate that the frontal and parietal neural networks involved in spatial working memory change over the adolescent age range and are further influenced by gender. These changes may represent evolving mnemonic strategies subserved by ongoing adolescent brain development.

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.

The Emergence of Collaborative Brain Function: fMRI Studies of the Development of Response Inhibition

Adolescence marks the beginning of adult-level cognitive control of behavior supported by the brain maturation processes of synaptic pruning and myelination. Cognitive development studies on adolescence indicate that this period is characterized by improvements in the performance of existing abilities including speed and capacity of information processing and the ability to have consistent cognitive control of behavior. Although adolescents can behave at adult levels in some ways, brain imaging studies indicate that the functional organization of brain systems that support higher-cognitive processes are not fully mature. Synaptic pruning allows for more efficient local computations, enhancing the ability of discrete brain regions to support high-level cognitive control of behavior including working memory. Myelination increases the speed of neuronal transmission supporting the collaboration of a widely distributed circuitry, integrating regions that support top-down cognitive control of behavior. Functional brain imaging methods allow for the characterization of the relationship between cognitive development and brain maturation as we can map progressions in the establishment of distributed brain circuitry and its relation to enhanced cognitive control of behavior. We present a review on the maturation (as distinct from "development" in emphasizing the transition to maturity and stabilization) of response inhibition, brain structure, and brain function through adolescence. We also propose a model for brain-behavior maturation that allows for the qualitative changes in cognitive processes that occur during adolescence.

Assessment of neuropsychological function through use of the Cambridge Neuropsychological Testing Automated Battery: performance in 4- to 12-year-old children

In this article, children's performance on subtasks from the Cambridge Neuropsychological Testing Automated Battery (CANTAB) is described. Two samples were recruited, one of which included children who spoke English as a second language. Children in this group also completed subtests from the Wechsler Intelligence Scale for Children-Third Revision (WISC-III). Despite the fact that ESL children scored over 1 SD below the norm on the WISC-III Vocabulary subtest, there were no CANTAB performance distinctions between primary versus secondary English-language speakers. In addition, several aspects of CANTAB performance were significantly correlated with verbal and nonverbal IQ. When developmental trends were examined, findings indicated that several aspects of frontal lobe function (memory span, working memory, and planning skills) are not functionally mature, by the age of 12 years. Implications for use of the CANTAB in clinical studies are discussed.

Neural basis of protracted developmental changes in visuo-spatial working memory

Developmental studies have shown that visuo-spatial working memory (VSWM) performance improves throughout childhood and adolescence into young adulthood. The neural basis of this protracted development is poorly understood. In this study, we used functional MRI (fMRI) to examine VSWM function in children, adolescents, and young adults, ages 7-22. Subjects performed a 2-back VSWM experiment that required dynamic storage and manipulation of spatial information. Accuracy and response latency on the VSWM task improved gradually, extending into young adulthood. Age-related increases in brain activation were observed in focal regions of the left and right dorsolateral prefrontal cortex, left ventrolateral prefrontal cortex (including Broca's area), left premotor cortex, and left and right posterior parietal cortex. Multiple regression analysis was used to examine the relative contributions of age, accuracy, and response latency on activation. Our analysis showed that age was the most significant predictor of activation in these brain regions. These findings provide strong evidence for a process of protracted functional maturation of bilateral fronto-parietal neural networks involved in VSWM development. At least two neural systems involved in VSWM mature together: (i) a right hemisphere visuo-spatial attentional system, and (ii) a left hemisphere phonological storage and rehearsal system. These observations suggest that visually and verbally mediated mnemonic processes, and their neural representations, develop concurrently during childhood and adolescence and into young adulthood.

Effects of age on neurocognitive measures of children ages 5 to 12: a cross-sectional study on 800 children from the United States

The standardization of the NEPSY-A Developmental Neuropsychological Assessment (Korkman, Kirk, & Kemp, 1998) provided an opportunity to study the effects of age across the age range 5 to 12 years. Test scores of 800 children on 20 subtests of NEPSY were analyzed. These measures are based on traditions of neuropsychological assessment and are thought to reflect attention and executive functions, language, sensorimotor functions, visuospatial functions, and memory and learning. The effects of age were very significant on all measures, confirming the developmental sensitivity of the NEPSY. The effects of age were more significant in the 5- to 8-year age range than in the 9- to 12-year range. Only performance on tasks of fluency and memory span for sentences showed significant age effects in the 10- to 12-year age range. This suggests that neurocognitive development is rapid in the 5- to 8-year age range and more moderate in the 9- to 12-year age range.

Active versus latent representations: a neural network model of perseveration, dissociation, and decalage

Children of different ages often perseverate, repeating previous behaviors when they are no longer appropriate, despite appearing to know what they should be doing. Using neural network models, we explore an account of these phenomena based on a distinction between active memory (subserved by the prefrontal cortex) and latent memory (subserved by posterior cortex). The models demonstrate how (a) perseveration occurs when an active memory of currently relevant knowledge is insufficiently strong to overcome a latent bias established by previous experience, (b) apparent dissociations between children's knowledge and action may reflect differences in the amount of conflict between active and latent memories that children need to resolve in the tasks, and (c) differences in when children master formally similar tasks (decalage) may result from differences in the strength of children's initial biases. The models help to clarify how prefrontal development may lead to advances in flexible thinking.

Evidence for a genetic etiology of early-onset delinquency

Age at onset of antisocial behavior discriminates persistent and transitory offenders. The authors proposed that early-onset delinquency has an underlying genetic influence that manifests in problems related to inhibition, whereas late-onset delinquency is more environmentally mediated. To test these notions, they selected 36 early starters, 86 late starters, and 25 nondelinquent controls from a large sample of 11-year-old twins and compared them on several measures related to inhibition and a peer group measure. As expected, early starters had more psychological, behavioral, and emotional problems related to inhibition than late starters and controls. A longitudinal analysis indicated an increase an antisocial behavior among peers of late starters shortly before their delinquency onset. Family history data and a twin analysis provided evidence of greater genetic influence on early-onset than late-onset delinquency.

Neuropsychological and oculomotor correlates of spatial working memory performance in schizophrenia patients and controls

Recent reports of spatial working memory deficits in schizophrenia provide evidence for dorsolateral prefrontal cortical (DLPFC) dysfunction. However, the question of how spatial working memory performance relates to other task impairments in schizophrenia considered reflective of frontal dysfunction, such as the Wisconsin Card Sorting Test (WCST) and smooth pursuit eye tracking, has been largely unexplored. Spatial working memory, as measured by a computerized visual-manual delayed response task (DRT), was evaluated in 42 schizophrenia patients and 54 normal controls. Subjects also completed a battery of neuropsychological and oculomotor tasks. Schizophrenia patients performed as accurately as controls on a no-delay, sensory-motor control condition, but showed a significant impairment in spatial accuracy with the addition of an 8-s delay and verbal distraction task. For the patients, working memory impairment was associated with fewer categories on the WCST, impaired eye tracking, fewer words learned on the Rey Auditory Verbal Learning Test, but not with measures of general cognitive and clinical functioning. Results suggest the presence of a sub-group of schizophrenia patients with common pathophysiology that accounts for the co-variance of several tasks implicating prefrontal dysfunction.