Age-related change in executive function: developmental trends and a latent variable analysis

Exekutive Funktionen: Zugrundeliegende kognitive Prozesse und deren Korrelate bei Kindern im späten Vorschulalter

Zusammenfassung. Die Bedeutung der Exekutiven Funktionen im Vorschulalter rückt zunehmend in den Fokus entwicklungspsychologischer Forschungsliteratur. Diese exekutiven Kontrollprozesse sind nicht nur zentral für die kognitive, soziale und motorische Entwicklung der Kinder im späten Vorschulalter, sondern gelten ebenso als bedeutsame Prädiktoren für den Schulerfolg. Die vorliegende Studie versucht auf der Grundlage der Daten von insgesamt 410 Kindern (61–88 Monate) die Frage von Entwicklungsveränderungen und Beziehungsmuster verschiedener Prozesse Exekutiver Funktionen zu klären. Die Befunde sprechen für eine wichtige Entwicklungsphase der Exekutiven Funktionen im späten Vorschulalter und bedeutsame Zusammenhänge zwischen den Exekutiven Funktionen und den Individualfaktoren Sprache, Intelligenz, Motorik und Selbstregulation sowie dem Umweltfaktor sozioökonomischer Status. Kein Zusammenhang wurde allerdings zwischen den Exekutiven Funktionen und der elterlichen Unterstützung bzw. Förderung gefunden. Die Ergebnisse werden bezüglich der Struktur des Konstrukts der Exekutiven Funktionen und hinsichtlich der Relevanz der Exekutiven Funktionen im Rahmen der Entwicklungsvoraussetzungen für die Schulbereitschaft diskutiert.

Relationships between magnitude representation, counting and memory in 4- to 7-year-old children: a developmental study

Background

The development of an evolutionarily grounded analogue magnitude representation linked to the parietal lobes is frequently thought to be a major factor in the arithmetic development of humans. We investigated the relationship between counting and the development of magnitude representation in children, assessing also children's knowledge of number symbols, their arithmetic fact retrieval, their verbal skills, and their numerical and verbal short-term memory.

Methods

The magnitude representation was tested by a non-symbolic magnitude comparison task. We have perfected previous experimental designs measuring magnitude discrimination skills in 65 children kindergarten (4-7-year-olds) by controlling for several variables which were not controlled for in previous similar research. We also used a large number of trials which allowed for running a full factorial ANOVA including all relevant factors. Tests of verbal counting, of short term memory, of number knowledge, of problem solving abilities and of verbal fluency were administered and correlated with performance in the magnitude comparison task.

Results and discussion

Verbal counting knowledge and performance on simple arithmetic tests did not correlate with non-symbolic magnitude comparison at any age. Older children performed successfully on the number comparison task, showing behavioural patterns consistent with an analogue magnitude representation. In contrast, 4-year-olds were unable to discriminate number independently of task-irrelevant perceptual variables. Sensitivity to irrelevant perceptual features of the magnitude discrimination task was also affected by age, and correlated with memory, suggesting that more general cognitive abilities may play a role in performance in magnitude comparison tasks.

Conclusion

We conclude that young children are not able to discriminate numerical magnitudes when co-varying physical magnitudes are methodically pitted against number. We propose, along with others, that a rather domain general magnitude representation provides the later basis for a specialized representation of numerical magnitudes. For this representational specialization, the acquisition of the concept of abstract numbers, together with the development of other cognitive abilities, is indispensable.

Children's (in)ability to recover from garden paths in a verb-final language: evidence for developing control in sentence processing

An eye-tracking study explored Korean-speaking adults' and 4- and 5-year-olds' ability to recover from misinterpretations of temporarily ambiguous phrases during spoken language comprehension. Eye movement and action data indicated that children, but not adults, had difficulty in recovering from these misinterpretations despite strong disambiguating evidence at the end of the sentence. These findings are notable for their striking similarities with findings from children parsing English; however, in those and other studies of English, children were found to be reluctant to use late-arriving syntactic evidence to override earlier verb-based cues to structure, whereas here Korean children were reluctant to use late-arriving verb-based cues to override earlier syntactic evidence. The findings implicate a general cross-linguistic pattern for parsing development in which late-developing cognitive control abilities mediate the recovery from so-called "garden path" sentences. Children's limited cognitive control prevents them from inhibiting misinterpretations even when the disambiguating evidence comes from highly informative verb information.

Attentional networks in developmental dyscalculia

BACKGROUND

Very little is known about attention deficits in developmental dyscalculia, hence, this study was designed to provide the missing information. We examined attention abilities of participants suffering from developmental dyscalculia using the attention networks test - interactions. This test was designed to examine three different attention networks--executive function, orienting and alerting--and the interactions between them.

METHODS

Fourteen university students that were diagnosed as suffering from developmental dyscalculia--intelligence and reading abilities in the normal range and no indication of attention-deficit hyperactivity disorder--and 14 matched controls were tested using the attention networks test-interactions. All participants were given preliminary tests to measure mathematical abilities, reading, attention and intelligence.

RESULTS

The results revealed deficits in the alerting network--a larger alerting effect--and in the executive function networks--a larger congruity effect in developmental dyscalculia participants. The interaction between the alerting and executive function networks was also modulated by group. In addition, developmental dyscalculia participants were slower to respond in the non-cued conditions.

CONCLUSIONS

These results imply specific attentional deficits in pure developmental dyscalculia. Namely, those with developmental dyscalculia seem to be deficient in the executive function and alertness networks. They suffer from difficulty in recruiting attention, in addition to the deficits in numerical processing.

Sexual orientation biases attentional control: a possible gaydar mechanism

Homosexuals are believed to have a “sixth sense” for recognizing each other, an ability referred to as gaydar. We considered that being a homosexual might rely on systematic practice of processing relatively specific, local perceptual features, which might lead to a corresponding chronic bias of attentional control. This was tested by comparing male and female homosexuals and heterosexuals – brought up in the same country and culture and matched in terms of race, intelligence, sex, mood, age, personality, religious background, educational style, and socio-economic situation – in their efficiency to process global and local features of hierarchically-constructed visual stimuli. Both homosexuals and heterosexuals showed better performance on global features – the standard global precedence effect. However, this effect was significantly reduced in homosexuals, suggesting a relative preference for detail. Findings are taken to demonstrate chronic, generalized biases in attentional control parameters that reflect the selective reward provided by the respective sexual orientation.

The Factor Structure and Age-Related Factorial Invariance of the Delis-Kaplan Executive Function System (D-KEFS)

There has been an increased interest in the structure of and relations among executive functions.The present study examined the factor structure as well as age-related factorial invariance of the Delis—Kaplan Executive Function System (D-KEFS), a widely used inventory aimed at assessing executive functions. Analyses were first conducted using data provided in the D-KEFS technical manual and were then replicated in an independent sample of male early adolescents aged 11 to 16 years. Results revealed a three-factor solution best fit the data across groups and samples; measurement properties appeared to be invariant across age groups for certain loadings and variant for others. The three factors were labeled Conceptual Flexibility, Monitoring, and Inhibition. These findings provide better understanding of the measurement properties of the D-KEFS and contribute to the larger literature on the structure of measures intended to assess executive functions.

Executive Functions after Age 5: Changes and Correlates

Research and theorizing on executive function (EF) in childhood has been disproportionately focused on preschool age children. This review paper outlines the importance of examining EF throughout childhood, and even across the lifespan. First, examining EF in older children can address the question of whether EF is a unitary construct. The relations among the EF components, particularly as they are recruited for complex tasks, appear to change over the course of development. Second, much of the development of EF, especially working memory, shifting, and planning, occurs after age 5. Third, important applications of EF research concern the role of school-age children's EF in various aspects of school performance, as well as social functioning and emotional control. Future research needs to examine a more complete developmental span, from early childhood through late adulthood, in order to address developmental issues adequately.

Executive functions in children with autism spectrum disorders

Executive dysfunction is a characteristic impairment of individuals with Autism Spectrum Disorders (ASD). However whether such deficits are related to autism per se, or to associated intellectual disability is unclear. This paper examines executive functions in a group of children with ASD (N=54, all IQ > or = 70) in relation to a typically developing control group individually matched on the basis of age, gender, IQ and vocabulary. Significant impairments in the inhibition of prepotent responses (Stroop, Junior Hayling Test) and planning (Tower of London) were reported for children with ASD, with preserved performance for mental flexibility (Wisconsin Card Sorting Task) and generativity (Verbal Fluency). Atypical age-related patterns of performance were reported on tasks tapping response inhibition and self-monitoring for children with ASD compared to controls. The disparity between these and previous research findings are discussed. A multidimensional notion of executive functions is proposed, with difficulties in planning, the inhibition of prepotent responses and self-monitoring reflecting characteristic features of ASD that are independent of IQ and verbal ability, and relatively stable across the childhood years.

Exekutive Funktionen bei Jungen mit Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung im Kindesalter

Die Studie ging der Frage nach, ob die uneinheitlichen Befunde zu einem globalen Defizit in exekutiven Funktionen bei Kindern mit Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) durch Altersunterschiede erklärt werden können. Es wurde ein zweifaktorieller Versuchsplan mit den Faktoren „Gruppe“ (n = 45 Jungen mit ADHS vom Mischtyp vs. n = 45 gesunde, nach Alter und Intelligenz parallelisierte Jungen) und „Alter“ (8 – 9 vs. 10 – 12 Jahre) untersucht. Insgesamt zeigten die Jungen mit ADHS in allen exekutiven Komponenten signifikant schlechtere Leistungen als die gesunden Jungen. Außerdem wiesen die jüngeren Jungen schlechtere exekutive Leistungen auf als die älteren Jungen. Demnach sprechen unsere Befunde für ein globales Defizit in den exekutiven Funktionen und für die Annahme einer Entwicklungsabweichung bei Jungen mit ADHS.

Executive cognitive functions and impulsivity as correlates of risk taking and problem behavior in preadolescents

Initiation of drug use and other risky behavior in preadolescence is associated with poor developmental outcomes. In this research, we examine models that ascribe the trajectory to (a) weak executive cognitive function (ECF), (b) early manifestation of externalizing problems, or (c) heightened levels of trait impulsivity. We test the explanatory power of these factors in a structural equation model with a community sample of 387 preadolescents ages 10-12 years. Participants were tested with a computerized battery of tasks to assess three facets of ECF (working memory, cognitive control, and reward processing) as well as with an audio assisted computerized self-interview to obtain reports of impulsivity and risk behaviors (use of cigarettes and alcohol as well as engaging in fighting and gambling for money) and a self-administered questionnaire to assess externalizing and internalizing problems. The best fitting model explained both early risk taking and externalizing symptoms as the result of individual differences in impulsivity. Although no ECF was directly related to risk taking, working memory and one measure of reward processing performance (reversal learning) were inversely related to impulsivity. The results are discussed in regard to theories of early risk taking with particular focus on the potential relation between ECF and impulsive behavior tendencies and the implications for early intervention to prevent the dysfunctional trajectory associated with early risk behavior.

Reduced attentional scope in cocaine polydrug users

Cocaine is Europe's second preferred recreational drug after cannabis but very little is known about possible cognitive impairments in the upcoming type of recreational cocaine user (monthly consumption). We asked whether recreational use of cocaine impacts early attentional selection processes. Cocaine-free polydrug controls (n = 18) and cocaine polydrug users (n = 18) were matched on sex, age, alcohol consumption, and IQ (using the Raven's progressive matrices), and were tested by using the Global-Local task to measure the scope of attention. Cocaine polydrug users attended significantly more to local aspects of attended events, which fits with the idea that a reduced scope of attention may be associated with the perpetuation of the use of the drug.

Age differences in perseveration: cognitive and neuroanatomical mediators of performance on the Wisconsin Card Sorting Test

Aging effects on the Wisconsin Card Sorting Test (WCST) are fairly well established but the mechanisms of the decline are not clearly understood. In this study, we examined the cognitive and neural mechanisms mediating age-related increases in perseveration on the WCST. MRI-based volumetry and measures of selected executive functions in conjunction with the WCST were obtained in a sample of 117 healthy young and older adults. Path analysis indicated that age-related increase in perseveration is completely accounted for by declines in processing speed and temporal processing, deficits in working memory mediated by decreased prefrontal cortical volume, and the indirect influence of prefrontally-mediated declines in inhibition via working memory. We conclude that age-related increase in perseveration is indeed differentially dependent on the integrity of prefrontal cortex and on declines in selected cognitive processes dependent on this region.

Recreational cocaine polydrug use impairs cognitive flexibility but not working memory

RATIONALE

Chronic use of cocaine is associated with dysfunctions in frontal brain regions and dopamine D2 receptors, with poorer mental flexibility and a reduced ability to inhibit manual and attentional responses. Little is known, however, about cognitive impairments in the upcoming type of recreational cocaine polydrug user (1-4 g monthly consumption).

OBJECTIVE

We studied whether recreational cocaine polydrug users, who do not meet the criteria for abuse or dependence, showed impairments in working memory (WM) and cognitive flexibility.

METHODS

Controls and recreational cocaine polydrug users (who abstained from cocaine and other substances more than 1 week) were matched by sex, age, alcohol consumption, and IQ (Raven's Standard Progressive Matrices). Groups were tested by using two cognitive tasks measuring cognitive flexibility and three tasks investigating the maintenance and monitoring of information in WM.

RESULTS

Recreational cocaine polydrug users performed significantly worse than controls on tasks tapping cognitive flexibility, but show comparable performance in the active maintenance and monitoring of information in WM.

CONCLUSIONS

The findings suggest that recreational use of cocaine selectively impairs cognitive flexibility but not the maintenance of information in WM. The inability to adjust behavior rapidly and flexibly may have repercussions for daily life activities.

Losing the big picture: how religion may control visual attention

Despite the abundance of evidence that human perception is penetrated by beliefs and expectations, scientific research so far has entirely neglected the possible impact of religious background on attention. Here we show that Dutch Calvinists and atheists, brought up in the same country and culture and controlled for race, intelligence, sex, and age, differ with respect to the way they attend to and process the global and local features of complex visual stimuli: Calvinists attend less to global aspects of perceived events, which fits with the idea that people's attentional processing style reflects possible biases rewarded by their religious belief system.

Cognitive development in macaques: Attentional set-shifting in juvenile and adult rhesus monkeys

In humans and nonhuman primates, the structure and function of frontal cortical regions of the brain are not completely developed until early adulthood. How this cortical development affects cognitive function continues to be elucidated. To that end, this experiment tested the ability of juvenile and adult rhesus monkeys to perform a cognitive task that is dependent upon intact frontal cortical function for optimal performance. Twenty-four juvenile (mean age 2.3 years) and 16 adult (mean age 10.3 years) rhesus monkeys were tested on the Cambridge Neuropsychological Test Automated Battery intradimensional/extradimensional set-shifting (ID/ED) task. Performance on the ID/ED task has been shown to be dependent upon frontal cortical function in both humans and nonhuman primates. Compared with adults, juveniles were impaired on the reversal of simple discrimination, intradimensional shift, reversal of intradimensional shift, and the extradimensional shift stages of the task. These results indicate juveniles committed more perseverative errors and more errors on the set-formation and set-shifting components of the ID/ED task. The developmental stage of the juvenile monkeys corresponds to roughly 5 to 6-year-old children, and these results are consistent with performance of human children and adults on similar ID/ED tests and on several other tests of attentional set-shifting or attentional flexibility. Furthermore, these results are consistent with the ongoing development of frontal cortical structures relating to ongoing cognitive development in nonhuman primates.

Evaluating the negative or valuing the positive? Neural mechanisms supporting feedback-based learning across development

How children learn from positive and negative performance feedback lies at the foundation of successful learning and is therefore of great importance for educational practice. In this study, we used functional magnetic resonance imaging (fMRI) to examine the neural developmental changes related to feedback-based learning when performing a rule search and application task. Behavioral results from three age groups (8-9, 11-13, and 18-25 years of age) demonstrated that, compared with adults, 8- to 9-year-old children performed disproportionally more inaccurately after receiving negative feedback relative to positive feedback. Additionally, imaging data pointed toward a qualitative difference in how children and adults use performance feedback. That is, dorsolateral prefrontal cortex and superior parietal cortex were more active after negative feedback for adults, but after positive feedback for children (8-9 years of age). For 11- to 13-year-olds, these regions did not show differential feedback sensitivity, suggesting that the transition occurs around this age. Pre-supplementary motor area/anterior cingulate cortex, in contrast, was more active after negative feedback in both 11- to 13-year-olds and adults, but not 8- to 9-year-olds. Together, the current data show that cognitive control areas are differentially engaged during feedback-based learning across development. Adults engage these regions after signals of response adjustment (i.e., negative feedback). Young children engage these regions after signals of response continuation (i.e., positive feedback). The neural activation patterns found in 11- to 13-year-olds indicate a transition around this age toward an increased influence of negative feedback on performance adjustment. This is the first developmental fMRI study to compare qualitative changes in brain activation during feedback learning across distinct stages of development.

Neural mechanisms supporting flexible performance adjustment during development

Feedback processing is crucial for successful performance adjustment following changing task demands. The present event-related fMRI study was aimed at investigating the developmental differences in brain regions associated with different aspects of feedback processing. Children age 8-11, adolescents age 14-15, and adults age 18-24 performed a rule switch task resembling the Wisconsin Card Sorting Task, and analyses focused on different types of negative and positive feedback. All age groups showed more activation in lateral orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (DLPFC), and superior parietal cortex following negative relative to positive performance feedback, but the regions contributed to different aspects of feedback processing and had separable developmental trajectories. OFC was adultlike by age 8-11, whereas parietal cortex was adultlike by age 14-15. DLPFC and ACC, in contrast, were still developing after age 14-15. These findings demonstrate that changes in separable neural systems underlie developmental differences in flexible performance adjustment. Supplementary data from this study are available online at the Psychonomic Society Archive of Norms, Stimuli, and Data, at www.psychonomic.org/archive.

Developmental changes in neural activation and psychophysiological interaction patterns of brain regions associated with interference control and time perception

Interference control and time perception are mediated by common neural networks, including the frontal and parietal lobes, the cerebellum and the basal ganglia. Previous studies have shown that while time perception develops early in life, interference control seems to follow a protracted course of maturation into late adolescence. Thus, the current study examined developmental changes in neural activation and functional interaction between brain regions during a combined time discrimination and interference control task using fMRI. Thirty-four participants, aged 8-15 years, were scanned while performing a spatial stimulus response compatibility (SRC) task and a time discrimination (TD) task using identical stimuli. We found shared neural activation in a fronto-parieto-cerebellar network as well as task-specific patterns of psychophysiological interaction with positive coupling between the right inferior frontal gyrus (IFG), the superior parietal lobes bilaterally, the contralateral IFG and the thalamus during interference control and positive interactions between the right IFG and bilateral cerebellar activity and the thalamus during time discrimination. Developmental changes in task performance and brain activation patterns were only observed during the SRC task, with increased neural activity in the left inferior parietal gyrus and positive coupling between fronto-parietal brain regions that was only observed in the adolescents group. These results suggest that although both cognitive tasks rely on a shared neural network, distinct developmental curves of brain activation and connectivity could be observed associated with differential maturation patterns underlying cognitive development.

A comparison of discrimination and reversal learning for olfactory and visual stimuli in aged rats

The present study investigated age-related differences in discrimination and reversal learning for olfactory and visual stimuli in 6-month and 24-month-old rats. Rats were trained to discriminate between two pseudo-randomly selected odors or objects. Once each animal reached a criterion on discrimination trials, the reward contingencies were reversed. Young and aged rats acquired the olfactory and visual discrimination tasks at similar rates. However, on reversal trials, aged rats required significantly more trials to reach the learning criterion on both the olfactory and visual reversal tasks than young rats. The deficit in reversal learning was comparable for odors and objects. Furthermore, the results showed that rats acquired the olfactory task more readily than the visual task. The present study represents the first examination of age-related differences in reversal learning using the same paradigm for odors and objects to facilitate cross-modal comparisons. The results may have important implications for the selection of memory paradigms for future research studies on aging.

Neurodevelopmental trajectories of the human cerebral cortex

Understanding the organization of the cerebral cortex remains a central focus of neuroscience. Cortical maps have relied almost exclusively on the examination of postmortem tissue to construct structural, architectonic maps. These maps have invariably distinguished between areas with fewer discernable layers, which have a less complex overall pattern of lamination and lack an internal granular layer, and those with more complex laminar architecture. The former includes several agranular limbic areas, and the latter includes the homotypical and granular areas of association and sensory cortex. Here, we relate these traditional maps to developmental data from noninvasive neuroimaging. Changes in cortical thickness were determined in vivo from 764 neuroanatomic magnetic resonance images acquired longitudinally from 375 typically developing children and young adults. We find differing levels of complexity of cortical growth across the cerebrum, which align closely with established architectonic maps. Cortical regions with simple laminar architecture, including most limbic areas, predominantly show simpler growth trajectories. These areas have clearly identified homologues in all mammalian brains and thus likely evolved in early mammals. In contrast, polysensory and high-order association areas of cortex, the most complex areas in terms of their laminar architecture, also have the most complex developmental trajectories. Some of these areas are unique to, or dramatically expanded in primates, lending an evolutionary significance to the findings. Furthermore, by mapping a key characteristic of these development trajectories (the age of attaining peak cortical thickness) we document the dynamic, heterochronous maturation of the cerebral cortex through time lapse sequences ("movies").

The prefrontal cortex: functional neural development during early childhood

The prefrontal cortex plays an essential role in various cognitive functions, such as planning and reasoning, yet little is known about how such neural mechanisms develop during childhood, particularly in young children. To better understand this issue, the present article reviews the literature on the development of the prefrontal cortex during early childhood, focusing mainly on the changes in structural architecture, neural activity, and cognitive abilities. Neuroanatomically, the prefrontal cortex undergoes considerable maturation during childhood, including a reduction of synaptic and neuronal density, a growth of dendrites, and an increase in white matter volume, thereby forming distributed neural networks appropriate for complex cognitive processing. Concurrently, behavioral performance of various cognitive tasks improves with age, and intercorrelations among performance on each task become weak through development. Furthermore, the correlation between subcategories of intelligence test decreases as general intellectual efficiency increases. In addition, recent neuroimaging findings suggest that the prefrontal cortex is already functional in 4-year olds and becomes organized into focal, fine-tuned systems through later development. The literature reviewed suggests that fractionation of the functional neural systems plays a key role in the development of prefrontal cortex and such fractionating process has already commenced in preschool children.

Individual differences in executive functions are almost entirely genetic in origin

Recent psychological and neuropsychological research suggests that executive functions--the cognitive control processes that regulate thought and action--are multifaceted and that different types of executive functions are correlated but separable. The present multivariate twin study of 3 executive functions (inhibiting dominant responses, updating working memory representations, and shifting between task sets), measured as latent variables, examined why people vary in these executive control abilities and why these abilities are correlated but separable from a behavioral genetic perspective. Results indicated that executive functions are correlated because they are influenced by a highly heritable (99%) common factor that goes beyond general intelligence or perceptual speed, and they are separable because of additional genetic influences unique to particular executive functions. This combination of general and specific genetic influences places executive functions among the most heritable psychological traits. These results highlight the potential of genetic approaches for uncovering the biological underpinnings of executive functions and suggest a need for examining multiple types of executive functions to distinguish different levels of genetic influences.

Age-group differences in set-switching and set-maintenance on the Wisconsin Card Sorting Task

This study examined developmental change in set-switching and set-maintenance on the Wisconsin Card Sorting Task (WCST), and sought to determine how executive function (EF) components (i.e., Working Memory, Shifting and Inhibition) may contribute to the observed changes on WCST performance. To this end, performance in four age groups (7-year-olds, 11-year-olds, 15-year-olds, and 21-year-olds) was measured on the WCST, and on three EF tasks assumed to tap Working Memory, Shifting, and Inhibition. The results showed that adult levels of performance were reached in 11-year-olds for set-switching, and in 15-year-olds for set-maintenance. A subsequent principal component analysis revealed that set-switching and set-maintenance loaded on two factors for 7-year-olds, but a single factor in the other age groups. Finally, regression analyses yielded a complex pattern of results concerning the prediction of set-switching and set-maintenance by the performance on tasks used to assess the EF components. The results were interpreted to suggest distinct developmental trends in set-switching and set-maintenance abilities required by the WCST.

Developmental Trends for Object and Spatial Working Memory: a Psychophysiological Analysis

This study examined developmental trends in object and spatial working memory (WM) using heart rate (HR) to provide an index of covert cognitive processes. Participants in 4 age groups (6-7, 9-10, 11-12, 18-26, n=20 each) performed object and spatial WM tasks, in which each trial was followed by feedback. Spatial WM task performance reached adult levels before object WM task performance. The differential developmental trends for object and spatial WM found in this study are taken to suggest that these WM components are separable. Negative performance feedback elicited HR slowing that was more pronounced for adults than for children. The development of performance monitoring as indexed by covert HR slowing following performance feedback contributes to WM performance.

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.

Brain regions mediating flexible rule use during development

During development, children improve at retrieving and using rules to guide their behavior and at flexibly switching between these rules. In this study, we used functional magnetic resonance imaging to examine the changes in brain function associated with developmental changes in flexible rule use. Three age groups (8-12, 13-17, and 18-25 years) performed a task in which they were cued to respond to target stimuli on the basis of simple task rules. Bivalent target stimuli were associated with different responses, depending on the rule, whereas univalent target stimuli were associated with fixed responses. The comparison of bivalent and univalent trials enabled the identification of regions modulated by demands on rule representation. The comparison of rule-switch and rule-repetition trials enabled the identification of regions involved in rule switching. We have used this task previously in adults and have shown that ventrolateral prefrontal cortex (VLPFC) and the (pre)-supplementary motor area (pre-SMA/SMA) have dissociable roles in task-switching, such that VLPFC is associated most closely with rule representation, and pre-SMA/SMA is associated with suppression of the previous task set (Crone et al., 2006a). Based on behavioral data in children (Crone et al., 2004), we had predicted that regions associated with task-set suppression would show mature patterns of activation earlier in development than regions associated with rule representation. Indeed, we found an adult-like pattern of activation in pre-SMA/SMA by adolescence, whereas the pattern of VLPFC activation differed among children, adolescents, and adults. These findings suggest that two components of task-switching--rule retrieval and task-set suppression--follow distinct neurodevelopmental trajectories.

A heart rate analysis of developmental change in feedback processing and rule shifting from childhood to early adulthood

Over the course of development, the ability to switch between different tasks on the basis of feedback cues increases profoundly, but the role of performance monitoring remains unclear. Heart rate indexes can provide critical information about how individuals monitor feedback cues indicating that performance should be adjusted. In this study, children of three age groups (8-10, 12-14, and 16-18 years) performed a rule change task in which sorting rules needed to be detected following positive or negative feedback. The number of perseverative errors was lower for 16- to 18-year-olds than for 8- to 10-year-olds, and 12- to 14-year-olds performed at an intermediate level. Consistent with previous findings, heart rate slowed following feedback indicating a rule change, and the magnitude of slowing was similar for all age groups. Thus, 8- to 10-year-olds are already able to analyze feedback cues. In contrast, 12- to 14-year-olds and 16- to 18-year-olds, but not 8- to 10-year-olds, showed heart rate slowing following performance errors, suggesting that with age children are increasingly able to monitor their performance online. Performance monitoring may therefore be an important contributor to set-shifting ability.