The ability to activate and inhibit speeded responses: separate developmental trends

Cognitive control in processing ambiguous idioms: evidence from a self-paced reading study

Idioms entail a competition between bottom-up and top-down activations of literal and figurative meanings. The present study explored the involvement of cognitive control in processing Hebrew ambiguous idioms. Fifty subjects have completed a self-paced reading task and a response inhibition, stop-signal task (SST). Subjects read 26 matched pairs of almost-identical sentences, which included ambiguous idioms (e.g., "break the ice"). The ambiguity was resolved only in the third part of the sentence, which was either literal ("on the parking lot") or figurative ("with funny stories"). Figurative disambiguation parts were read significantly faster than literal ones. The means of the absolute RT difference between the literal and figurative sentences significantly correlated with the SST cognitive control measure. A comparison between three groups of cognitive control levels validated that "Good inhibitors" in the SST were also faster in processing ambiguities. The paper discusses the generality of cognitive control in linguistic processing.

Global Cognitive Functioning versus Controlled Functioning throughout the Stages of Development

According to the All or None Hypothesis (Diamond, 2009), the cognitive system can operate in a global manner that is not very discriminate or in a more discriminate mode that demands greater precision, control, and cognitive effort. There are five corollaries to this hypothesis that describe, in an operative way, the conditions under which the controlled mode of functioning in the cognitive domain can be activated and thus tested. Given the impact this theory has generated and the absence of studies analyzing the corollaries in a collective and systematic way at different stages of development, this study was proposed, first of all, to test three of these corollaries in children, adolescents and adults and, secondly, to analyze the changes in the controlled mode of functioning during these three stages of development. To this end, the Fingers Task, a modified version of Arrows Task (with two rules: response ipsilateral where the stimulus is presented, symmetry; and response contralateral, asymmetry), was administered to a sample of 123 participants (43 children, 44 adolescents, and 36 adults). In general, the results verify the corollaries and identify the changes that the controlled mode of functioning experiences at different stages of development.

A Novel Approach to Measure Executive Functions in Students: An Evaluation of Two Child-Friendly Apps

Interest in measurement of children's executive functions has shown a major increase over the past two decades. The present study evaluates two new apps (EYT and eFun) for measuring executive functions in children. The results of this study show that children (aged 5-8) enjoy executive function assessment in the form of games on an iPad. However, only one executive function, EYT working memory, showed significant positive correlations with several types of grades (e.g., English and maths) in primary school students. New, self-assessed, child-friendly executive function measurement tools have the potential to provide future possibilities for teachers to integrate information on cognitive ability into student learning plans.

Perceptual inhibition of emotional interference in children

In daily life, when a bee approaches us while we are sitting in the garden, we must pay attention to that threatening stimulus and give an appropriate response. However, if this bee approaches us while riding a bike, we must inhibit that distractor to avoid an accident. In this case, avoiding the interference of an emotional stimuli and continuing with the task should be preferential. In general, perceptual inhibition is responsible for controlling and suppressing the environmental distractions that interrupt the course of the realization of a goal. In this study, 435 children performed a modified flanker task with entirely irrelevant emotional and neutral stimuli in order to assess perceptual inhibition in contexts with high and low emotional salience. The results showed that entirely irrelevant distractors affected performance, but that there were no significant differences according to whether these distractors were emotionally salient or neutral. These results constitute a first approach to the problem of emotional interference in children considering the multidimensional approach of inhibition.

Natural Environment and Social Relationship in the Development of Attentional Network

The attention mechanism is related to both voluntary and automatic processes, that may be summarized in three distinct networks: alert, orientation, and inhibitory control. These networks can be modulated by different contextual and relational situations. Aim of this review is to explain how a combination of natural and social stimuli can positively affect the attentional processes. It has been proposed that the exposition to natural environment can positively affect direct attention, a common resource supporting both executive functioning and self-regulation processes in cognition. It has been suggested that the decrease of the effort required to voluntary control attention from the bottom upwards could determine some internal reflection that may support creative thinking secondarily to a simultaneous reduction in the effort required to orient attention between thoughts and impressions. In my view, not only exposition to natural and green environment improves attentional processes but also the involvement in social relationship. The development of the orientation and inhibitory control networks is sensitive to the social nature of the stimuli, for instance, in a task, including socially relevant stimuli the efficiency of these two attentional networks increases in children, in adults and in elderly subjects. Social attention, starting very early in the life (joint attention) is a very important mechanism for the regulation of social relationships. A key for a better development of cognitive functions such as attentional processes is the promotion of the immersion in the natural environment and the involvement in social relationship.

The developing predictive brain: How implicit temporal expectancy induced by local and global prediction shapes action preparation across development

Human behavior is continuously shaped not just as a function of explicitly responding to external world events but also by internal biases implicitly driven by the capacity to extract statistics from complex sensory patterns. Two possible sources of predictability engaged to generate and update temporal expectancy are the implicit extraction of either local or global statistical contingencies in the events' temporal structure. In the context of action preparation the local prediction has been reported to be stable from the age of 6. However, there is no evidence about how the ability to extract and use global statistical patterns to establish temporal expectancy changes across development. Here we used a new, child-friendly reaction time task purposely designed to investigate how local (within-trial expectancy bias) and global (between-block expectancy bias) prediction interplay to generate temporal expectancy and consequently shape action preparation in young (5- to 6-year-old), middle-aged (7- to 8-year-old) and old (9- to 10-year-old) typically developing children. We found that while local temporal prediction showed stable developmental trajectories, the ability to use a global rule to action preparation in terms of both accuracy and speed becomes stable after the age of seven. These findings are discussed by adopting a neuroconstructivist-inspired theoretical account, according to which the developmental constraints on learning from hierarchically nested levels of sensory complexity may constitute a necessary prerequisite for mastering complex domains.

The interplay between cognitive control and emotional processing in children and adolescents

This study examined interactions between cognitive control and emotional processing throughout adolescent development. In particular, we investigated whether age differences in response inhibition and initiation were influenced by an emotional expression of faces and whether the effects differed from processing of nonemotional features of faces. Therefore, we applied two versions of a Go/No-go task, an emotional task requiring responding or withholding responding to happy and angry faces, and a gender task including decisions to female and male faces in a large sample (N = 187, age range = 9-18 years). Considering theoretical assumptions of dual-system models that mid-adolescents are more susceptible to the processing of emotional contents, we expected more inefficient response inhibition on happy and angry trials than on neutral trials. We also expected that these effects would be specific to emotional contents. Results indicated that both response inhibition and initiation showed linear improvements with increasing age. Response inhibition was hampered in the presence of happy and angry faces, especially in mid-adolescents and late adolescents. In contrast, response initiation was highly facilitated to happy faces, indicating a happy effect, leading to more accurate responding in all age groups and to faster responding especially in late adolescents. Children, in contrast to late adolescents, were more accurate in response inhibition and initiation when the gender was task relevant. Results are in line with dual-system models, assuming a higher sensitivity to emotional features from mid-adolescents onward but not to other features such as gender.

How Do Children Deal With Conflict? A Developmental Study of Sequential Conflict Modulation

This study examined age-related differences in sequential conflict modulation (SCM), elicited in three tasks requiring the inhibition of pre-potent responses; a Simon task, an S-R compatibility (SRC) task and a hybrid Choice-reaction/NoGo task. The primary focus was on age-related changes in performance changes following a conflict trial. A secondary aim was to assess whether SCM follows different developmental trajectories depending on the type of conflict elicited by the tasks. The tasks were presented to three different groups of participants with an age range between 7- to 25-years-one group of participants for each task. For each task, the response-to-stimulus interval (RSI) was manipulated (50 vs. 500 ms) across trial blocks to assess time-dependent changes in conflict modulation. The results showed SCM for all three tasks, although the specific patterns differed between tasks and RSIs. Importantly, the magnitude of SCM decreased with advancing age, but this developmental trend did not survive when considering age-group differences in basic response speed. The current results contribute to the emerging evidence suggesting that patterns of SCM are task specific and were interpreted in terms of multiple bottom-up control mechanisms.

Neural Correlates of Response Inhibition in Early Childhood: Evidence From a Go/No-Go Task

We examined the neural correlates underlying response inhibition in early childhood. Five-year-old children completed a Go/No-go task with or without time pressure (Fast vs. Slow condition) while scalp EEG was recorded. On No-go trials where inhibition was required, the left frontal N2 and posterior P3 were enhanced relative to Go trials. Time pressure was detrimental to behavioral performance and modulated the early-occurring P1 component. The topography of ERPs related to response inhibition differed from patterns typically seen in adults, and may indicate a compensatory mechanism to make up for immature inhibition networks in children.

Development of Risk-Taking, Perspective-Taking, and Inhibitory Control During Adolescence

Structural and functional brain development is thought to lead to different developmental progressions of cognitive control, risk/reward processing, and social cognition during adolescence. We compared these abilities in a cross-sectional sample of 90 adolescents aged 12, 15, or 17 years old, using computerized measures of inhibitory control (Go/No-Go task), risk-taking (Balloon Analogue Risk task), and social perspective-taking (Director task). Fifteen-year-olds exhibited better inhibitory control than 12-year-olds, while 17-year-olds exhibited greater perspective-taking than younger adolescents. Risk-taking was greater in older adolescents than 12-year-olds when controlling for inhibitory control. These findings are consistent with earlier findings obtained in separate samples.

Development of impulse control circuitry in children of alcoholics

BACKGROUND

Difficulty with impulse control is heightened in children with a family history of alcohol use disorders and is a risk factor for later substance problems. Cross-sectional functional magnetic resonance imaging studies have shown altered impulse control processing in adolescents with a positive family history, yet developmental trajectories have yet to be examined.

METHODS

Longitudinal functional magnetic resonance imaging was conducted in children of alcoholic families (family history positive [FH+]; n = 43) and children of control families (family history negative [FH-]; n = 30) starting at ages 7-12 years. Participants performed a go/no-go task during functional magnetic resonance imaging at intervals of 1-2 years, with two to four scans performed per subject. We implemented a repeated-measures linear model fit across all subjects to conduct a whole-brain search for developmental differences between groups.

RESULTS

Performance improved with age in both groups, and there were no performance differences between groups. Significant between-group differences in linear age-related activation changes were found in the right caudate, middle cingulate, and middle frontal gyrus. Post hoc analyses revealed significant activation decreases with age in the caudate and middle frontal gyrus for FH- subjects and a significant increase with age in middle cingulate activation for FH+ subjects. Group differences were evident at age 7-12 years, even in alcohol- and drug-naïve participants, with FH+ subjects showing significantly blunted activation at baseline compared with FH- subjects.

CONCLUSIONS

Differences in response inhibition circuitry are visible in FH+ individuals during childhood; these differences continue into adolescence, displaying trajectories that are inconsistent with development of normal response inhibition. These patterns precede problem drinking and may be a contributing factor for subsequent substance use problems.

Development of response activation and inhibition in a selective stop-signal task

To gain more insight into the development of action control, the current brain potential study examined response selection, activation, and selective inhibition during choice- and stop-signal processing in three age groups (8-, 12-, and 21-year-olds). Results revealed that age groups differed in the implementation of proactive control; children slowed their go response and showed reduced cortical motor output compared to adults. On failed inhibition trials, children were less able than adults to suppress muscle output resulting in increased partial-inhibition rates. On invalid stop trials, all age groups initially activated, subsequently inhibited, and then reactivated the go response. Yet, children were less efficient in implementing this strategy. Then, older children recruit motor responses to a greater extent than younger children and adults, which reduced the efficiency of implementing response inhibition and proactive control. The results are discussed in relation to current notions of developmental change in proactive and reactive action control.

Emotional modulation of the ability to inhibit a prepotent response during childhood

The present study examined the bottom-up influence of emotional context on response inhibition, an issue that remains largely unstudied in children. Thus, 62 participants, aged from 6 to 13 years old, were assessed with three stop signal tasks: one with circles, one with neutral faces, and one with emotional faces (happy and sad). Results showed that emotional context altered response inhibition ability in childhood. However, no interaction between age and emotional influence on response inhibition was found. Positive emotions were recognized faster than negative emotions, but the valence did not have a significant influence on response inhibition abilities.

Inhibitory Control Differentiates Rare Target Search Performance in Children

Age-related differences in rare-target search are primarily explained by the speed-accuracy trade-off, primed responses, or decision making. The goal was to examine how motor inhibition influences visual search. Children pressed a key when a rare target was detected. On no-target trials, children withheld reactions. Response time (RT), hits, misses, correct rejection, and false alarms were measured. Tapping tests assessed motor control. Older children tapped faster, were more sensitive to rare targets (higher d'), and reacted more slowly than younger ones. Girls outperformed boys in search sensitivity but not in RT. Motor speed was closely associated with hit rate and RT. Results suggest that development of inhibitory control plays a key role in visual detection. The potential implications for cognitive-motor development and individual differences are discussed.

Lifespan changes in global and selective stopping and performance adjustments

This study examined stopping and performance adjustments in four age groups (M ages: 8, 12, 21, and 76 years). All participants performed on three tasks, a standard two-choice task and the same task in which stop-signal trials were inserted requiring either the suppression of the response activated by the choice stimulus (global stop task) or the suppression of the response when one stop-signal was presented but not when the other stop-signal occurred (selective stop task). The results showed that global stopping was faster than selective stopping in all age groups. Global stopping matured more rapidly than selective stopping. The developmental gain in stopping was considerably more pronounced compared to the loss observed during senescence. All age groups slowed the response on trials without a stop-signal in the stop task compared to trials in the choice task, the elderly in particular. In addition, all age groups slowed on trials following stop-signal trials, except the elderly who did not slow following successful inhibits. By contrast, the slowing following failed inhibits was disproportionally larger in the elderly compared to young adults. Finally, sequential effects did not alter the pattern of performance adjustments. The results were interpreted in terms of developmental change in the balance between proactive and reactive control.

Language disorders in children with central nervous system injury

Children with injury to the central nervous system (CNS) exhibit a variety of language disorders that have been described by members of different disciplines, in different journals, using different descriptors and taxonomies. This paper is an overview of language deficits in children with CNS injury, whether congenital or acquired after a period of normal development. It first reviews the principal CNS conditions associated with language disorders in childhood. It then describes a functional taxonomy of language, with examples of the phenomenology and neurobiology of clinical deficits in children with CNS insults. Finally, it attempts to situate language in the broader realm of cognition and in current theoretical accounts of embodied cognition.

Motivational influences on response inhibition measures

Psychological research has placed great emphasis on inhibitory control due to its integral role in normal cognition and clinical disorders. The stop-signal task and associated measure--stop-signal reaction time (SSRT)--provides a well-established paradigm for measuring response inhibition. However, motivational influences on stop-signal performance and SSRT have not been examined. We conceptualize the stop-signal paradigm as a decision-making task involving the trade-off between fast responding and accurate inhibition. In 4 experiments, we demonstrate that performance trade-offs are influenced by inherent motivational biases and explicit strategic control. As a result, SSRT was lower when participants favored correct stopping over fast responding than when the same participants favored fast responding over correct stopping. We present a novel variant of the stop-signal task that uses monetary incentives to manipulate motivated speed-accuracy trade-offs. By sampling performance at multiple-trade-off settings, we obtain a measure of inhibitory ability that is independent of trade-off bias, and thus, more easily interpretable when comparing across participants. We present a working theoretical model to explain the effects of motivational context on response inhibition.

Age-related cognitive gains are mediated by the effects of white matter development on brain network integration

A fundamental, yet rarely tested premise of developmental cognitive neuroscience is that changes in brain activity and improvements in behavioral control across adolescent development are related to brain maturational factors that shape a more efficient, highly-interconnected brain in adulthood. We present the first multimodal neuroimaging study to empirically demonstrate that maturation of executive cognitive ability is directly associated with the relationship of white matter development and age-related changes in neural network functional integration. In this study, we identified specific white matter regions whose maturation across adolescence appears to reduce reliance on local processing in brain regions recruited for conscious, deliberate cognitive control in favor of a more widely distributed profile of functionally-integrated brain activity. Greater white matter coherence with age was associated with both increases and decreases in functional connectivity within task-engaged functional circuits. Importantly, these associations between white matter development and brain system functional integration were related to behavioral performance on tests of response inhibition, demonstrating their importance in the maturation of optimal cognitive control.

Theory of mind depends on domain-general executive functions of working memory and cognitive inhibition in children with traumatic brain injury

Relations among theory of mind (ToM), the executive functions of working memory and cognitive inhibition, and frontal lesions were studied using path analysis in 43 school-aged children with traumatic brain injury. The relation between cognitive inhibition and ToM involved a single mediated path, such that cognitive inhibition predicted ToM through working memory. Frontal injury had a direct impact on working memory, which then separately determined ToM performance, the direct single paths between frontal injury and ToM being nonsignificant. The expression of ToM in school-age children with traumatic brain injury is not domain specific, but instead depends on the domain-general functions of working memory and cognitive inhibition.

The development of selective inhibitory control: the influence of verbal labeling

The role of language in the development of selective inhibitory control was examined in four groups: Children aged 7-9 years, children aged 11-13 years, adults aged 20-27 years, and adults aged 62-76 years. We used a modified stop-signal task in which participants inhibited or executed responses based on a visual signal. Response execution and inhibition were assessed by measurement of reaction times (RTs) and error rates to a go signal and RTs to a stop signal. Four task variations were compared in which subjects named (1) the stimulus, (2) the intended action (go/stop), (3) something irrelevant, or (4) nothing. Results showed different developmental trends for response execution and inhibition across the lifespan. Moreover, response execution was faster and more accurate when subjects named the stimulus instead of the intended action. The increase in response accuracy when naming the stimulus was greatest for children. In contrast to expectations, naming the intended action did not influence response inhibition. Overall, these findings suggest that verbal labeling supports the initiation but not the inhibition of actions.

Functional neural networks underlying response inhibition in adolescents and adults

This study provides the first description of neural network dynamics associated with response inhibition in healthy adolescents and adults. Functional and effective connectivity analyses of whole brain hemodynamic activity elicited during performance of a Go/No-Go task were used to identify functionally integrated neural networks and characterize their causal interactions. Three response inhibition circuits formed a hierarchical, inter-dependent system wherein thalamic modulation of input to premotor cortex by fronto-striatal regions led to response suppression. Adolescents differed from adults in the degree of network engagement, regional fronto-striatal-thalamic connectivity, and network dynamics. We identify and characterize several age-related differences in the function of neural circuits that are associated with behavioral performance changes across adolescent development.

A Developmental Investigation of Stop-Signal Inhibition

Abstract. The present study examined the development of response inhibition in the stop-signal task across child (8-13 years), young-adult (18-22 years), and middle-aged adult (29-47 years) groups through a dissociation of low- and higher-frequency ERP activity. Fifty-one subjects (n = 17 in each group) performed the stop-signal task, which consisted of a visual choice reaction time (RT) task and auditory stop-signals, while EEG was recorded. The original EEG data (0.01-30 Hz) was subsequently filtered to separate slow-wave (0.01-2 Hz) and residual (2-30 Hz) activity. Performance findings revealed that stop-signal reaction time (SSRT) decreased from the child to young-adult group and then showed a small increase in the middle-aged adult group. Original ERPs revealed decreasing N1 and N2 amplitudes and increasing P2 and P3 amplitudes across the scalp with increasing age for successful-stop trials. These developmental effects did not occur in the residual waveforms after removal of slow-wave activity. For failed-stop trials, a response-locked negative component, identified as the error-negativity (Ne), showed an age-related decrease in amplitude across the scalp in the residual, but not the original, waveform. The error-positivity (Pe) increased in amplitude with age in the original data, but this was accounted for by a positive slow-wave (PSW). Together, the findings suggest that underlying slow-wave activity accounts for a large number of developmental effects in the traditionally quantified ERP components, but may also obscure effects occurring in residual activity. These findings highlight the importance of dissociating low- and higher-frequency ERP activity in developmental research.

Developmental relations between working memory and inhibitory control

Working memory (WM) and inhibitory control (IC) are general-purpose resources that guide cognition and behavior. In this study, the developmental relations between WM and IC were investigated in 96 typically developing children aged 6 to 17 years in an experimental task paradigm using an efficiency metric that combined speed and accuracy performance. The ability to activate and process information in WM showed protracted age-related growth. Performance involving WM and IC together was empirically distinguishable from that involving WM alone. The results indicate that developmental improvements in WM are attributable to increased processing efficiency in activation, suppression, and strategic resource deployment, and that WM and IC are best studied in novel, complex situations that elicit competition among those resources.

The development of stop-signal and Go/Nogo response inhibition in children aged 7–12 years: Performance and event-related potential indices

The present study examined the development of response inhibition during the Stop-signal and Go/Nogo tasks in children using performance and ERP measures. Twenty-four children aged 7 to 12 years completed both tasks, each with an auditory Nogo/Stop-signal presented on 30% of trials. On average, response inhibition was more difficult in the Stop-signal than Go/Nogo task. Response inhibition performance did not develop significantly across the age range, while response execution varied significantly in a task dependent manner (Go/Nogo: increasing accuracy and reducing response variability with age; Stop-signal: reducing Go mean reaction time and response variability with age). The N1, P2, N2 and P3 components showed different scalp distributions, with N1 and P2 peaking earlier, and P3 later, in Nogo compared to Stop stimuli. N2 and P3 amplitude were positively correlated with successful inhibition probability in the Go/Nogo task only. N2 amplitude and latency to both Nogo and successful Stop stimuli decreased linearly with age, but not in the frontal regions. N1 and P3 amplitude in the parietal region increased with age for Stop-signals. An age-related reduction in P3 latency to Nogo stimuli correlated significantly with reduced RT and variability in Go responding, indicating a relationship between efficient Nogo and Go processing. Together the behavioural and ERP results suggest little development of the response inhibition process as measured via the Stop-signal and Go/Nogo tasks across the 7 to 12 year age range, while response execution processes develop substantially.

Neural correlate of spatial presence in an arousing and noninteractive virtual reality: an EEG and psychophysiology study

Using electroencephalography (EEG), psychophysiology, and psychometric measures, this is the first study which investigated the neurophysiological underpinnings of spatial presence. Spatial presence is considered a sense of being physically situated within a spatial environment portrayed by a medium (e.g., television, virtual reality). Twelve healthy children and 11 healthy adolescents were watching different virtual roller coaster scenarios. During a control session, the roller coaster cab drove through a horizontal roundabout track. The following realistic roller coaster rides consisted of spectacular ups, downs, and loops. Low-resolution brain electromagnetic tomography (LORETA) and event-related desynchronization (ERD) were used to analyze the EEG data. As expected, we found that, compared to the control condition, experiencing a virtual roller coaster ride evoked in both groups strong SP experiences, increased electrodermal reactions, and activations in parietal brain areas known to be involved in spatial navigation. In addition, brain areas that receive homeostatic afferents from somatic and visceral sensations of the body were strongly activated. Most interesting, children (as compared to adolescents) reported higher spatial presence experiences and demonstrated a different frontal activation pattern. While adolescents showed increased activation in prefrontal areas known to be involved in the control of executive functions, children demonstrated a decreased activity in these brain regions. Interestingly, recent neuroanatomical and neurophysiological studies have shown that the frontal brain continues to develop to adult status well into adolescence. Thus, the result of our study implies that the increased spatial presence experience in children may result from the not fully developed control functions of the frontal cortex.

Developmental changes in unimanual and bimanual aiming movements

The aim of this study was twofold: (a) analyze the development of reaction time (RT) and movement time (MT) for bimanual and unimanual movements and (b) investigate the interaction of age and sex on the changes in RT and MT. Participants (5-, 8-, and 11-year-olds) were asked to aim at target buttons under three conditions of movement: unimanual, bimanual symmetrical, and bimanual nonsymmetrical. As expected, RTs for bimanual symmetrical movements were shorter than RTs for unimanual and bimanual nonsymmetrical movements in the 5-year-olds. By the age of 8, bimanual nonsymmetrical movements still yielded longer RTs than unimanual and bimanual symmetrical movements, which no longer differed from each other. Regarding MT, in the 2 younger groups there was an advantage of unimanual over bimanual symmetrical movements. The latter were executed faster than nonsymmetrical movements at all ages. These results suggest that the evolution of RT and MT with age reflects development of interhemispheric transfer of information. It appears that the functional improvement of such transfer, which depends on the corpus callosum, progressively enables contralateral motor inhibition and the coordination of complex bilateral movements. The exchange of movement feedback information could mature more slowly than that of feed-forward information, explaining the extended time course of MT evolution.

Development of cognitive control and executive functions from 4 to 13 years: evidence from manipulations of memory, inhibition, and task switching

Predictions concerning development, interrelations, and possible independence of working memory, inhibition, and cognitive flexibility were tested in 325 participants (roughly 30 per age from 4 to 13 years and young adults; 50% female). All were tested on the same computerized battery, designed to manipulate memory and inhibition independently and together, in steady state (single-task blocks) and during task-switching, and to be appropriate over the lifespan and for neuroimaging (fMRI). This is one of the first studies, in children or adults, to explore: (a) how memory requirements interact with spatial compatibility and (b) spatial incompatibility effects both with stimulus-specific rules (Simon task) and with higher-level, conceptual rules. Even the youngest children could hold information in mind, inhibit a dominant response, and combine those as long as the inhibition required was steady-state and the rules remained constant. Cognitive flexibility (switching between rules), even with memory demands minimized, showed a longer developmental progression, with 13-year-olds still not at adult levels. Effects elicited only in Mixed blocks with adults were found in young children even in single-task blocks; while young children could exercise inhibition in steady state it exacted a cost not seen in adults, who (unlike young children) seemed to re-set their default response when inhibition of the same tendency was required throughout a block. The costs associated with manipulations of inhibition were greater in young children while the costs associated with increasing memory demands were greater in adults. Effects seen only in RT in adults were seen primarily in accuracy in young children. Adults slowed down on difficult trials to preserve accuracy; but the youngest children were impulsive; their RT remained more constant but at an accuracy cost on difficult trials. Contrary to our predictions of independence between memory and inhibition, when matched for difficulty RT correlations between these were as high as 0.8, although accuracy correlations were less than half that. Spatial incompatibility effects and global and local switch costs were evident in children and adults, differing only in size. Other effects (e.g., asymmetric switch costs and the interaction of switching rules and switching response-sites) differed fundamentally over age.

Developmental changes in the functional brain responses of adolescents to images of high and low-calorie foods

We examined cerebral responses to visually presented food images in children and adolescents. Eight healthy normal-weight females (ages 9-15) underwent functional magnetic resonance imaging (fMRI) while viewing photographs of high- and low-calorie foods and dining utensils. In general, food images yielded significant activation within the inferior orbitofrontal cortex, hippocampus, and fusiform gyri. High calorie food images activated the left hippocampus and subgenual cingulate, and age correlated positively with activity within the orbitofrontal cortex but negatively with activity within the anterior cingulate gyrus. Low-calorie foods activated the fusiform gyrus and demonstrated age-related increases in the left superior temporal gyrus and anterior cingulate. Utensils activated the fusiform gyrus and showed age-related increases in the prefrontal cortex. Data were also compared statistically to a sample of adults exposed to the same stimulus conditions. Findings support a developmental model of adolescent maturation whereby age-related changes in cerebral functioning develop from lower-order sensory processing toward higher-order processing of stimuli via prefrontal cortical systems involved in reward anticipation, self-monitoring, and behavioral inhibition.

Response Inhibition After Traumatic Brain Injury (TBI) in Children: Impairment and Recovery

Children who experience traumatic brain injury (TBI) often show cognitive impairments postinjury, some of which recover over time. We examined the recovery of motor response inhibition immediately following TBI and over 2 years. We assessed the role of injury severity, age at injury, and lesion characteristics on initial impairment and recovery while considering the role of pre-injury psychiatric disorder. Participants were 136 children with TBI aged 5-16 years. Latency of motor response inhibition was measured with the stop-signal task within 1 month of the injury and again at 3, 6, 12, and 24 months. The performance of the TBI participants at each measurement occasion was standardized with 117 children of similar age, but without injury. Residualized latency scores were calculated. Growth curve analyses showed an initial impairment in response inhibition and improvement over the 2 years following injury. Younger TBI patients were initially more impaired although they exhibited greater recovery of response inhibition than did older TBI patients. Longer duration of coma, but not reactivity of pupils or Glasgow Coma Scale score, predicted initial deficit. Lesion characteristics or pre-injury attention deficit hyperactivity disorder did not predict initial impairment or recovery. Replication with longitudinal testing of a comparison group of children sustaining extracranial injury is necessary to confirm our findings.

Attention deficit and impulsivity: Selecting, shifting, and stopping

The present selective review addresses attention, inhibition, and their underlying brain mechanisms, especially in relation to attention deficit/hyperactivity disorders (AD/HD), and the effects of methylphenidate. In particular, event-related potential (ERP) studies suggest a deficit in the early-filtering aspect of selective attention in children with AD/HD. Results from stop tasks are consistent with impairments in stopping performance in AD/HD, but in children (as opposed to adults) these effects cannot be easily dissociated from more general impairments in attention to the task, and therefore an interpretation in terms of inhibitory control is not straightforward. On the other hand, the beneficial effects of methylphenidate are more specific to stopping, and there are no clearcut effects of methylphenidate on measures of selective attention. Even when group differences pertain specifically to stopping performance (as with adults with AD/HD), ERP evidence suggests at least a partial contribution of differences in switching attention to the stop signal, as revealed in measures of sensory cortex activation. ERP evidence from cued go/nogo tasks underlines the importance of taking into account the contribution of higher order control processes involved in anticipation of and preparation for task stimuli. It suggests that in certain conditions, expectancy, rather than response bias, contributes to increased behavioral response tendencies, and that a presumed index of response inhibition, the nogo N2, may rather reflect conflict monitoring. In sum, direct reflections of brain activity suggest that mechanisms of expectation and attention, rather than of response bias or inhibitory control, govern behavioral manifestations of impulsivity.

The course of neuropsychological functions in children with attention deficit hyperactivity disorder from late childhood to early adolescence

OBJECTIVE

The aim of this follow-up study was to investigate the course of performance in attentional tasks in children with ADHD and normal controls in late childhood and preadolescence over short periods of time. The development of two dimensions of attention was compared: alertness/arousal and inhibitory control.

METHOD

Children with ADHD (N=28) and normal controls (N=25) were examined at three times: at baseline (age mean=10.8 years, SD=1.5), after one year (age mean=12.0 years, SD=1.6), and after 2.6 years (age mean=13.3 years, SD=1.6). They performed two tasks of a computerized battery for attentional performance: Alertness--a test of simple reaction time to visual stimuli contrasting a condition with and without auditory warning signal, and Incompatibility--a test of spatial interference/inhibitory control. Clinical diagnosis according to DSM-III-R criteria was established at time 1 and time 3 by structured diagnostic interviews.

RESULTS

In the Alertness task significant group differences regarding increased reaction time variability in ADHD, but not for reaction time itself, were found at time 1 and more pronounced at time 2. At time 3 group differences had disappeared. In the Incompatibility task group differences in number of errors were not observed at time 1, whereas children with ADHD made significantly more errors at time 2 and less pronounced at time 3. The degree of clinical symptom remission after 2.6 years was not related to changes in neuropsychological performance.

CONCLUSION

When measuring attentional functions, the selection of an appropriate time window seems to be essential for the detection of group differences between ADHD children and controls, because group differences are most pronounced before adolescence. The different developmental course of selective components of attention should be taken into account.

Juvenile Lymnaea ventilate, learn and remember differently than do adult Lymnaea

Adult snails are capable of learning associatively not to perform aerial respiration and then to consolidate the acquired behaviour into long-term memory (LTM). Juvenile Lymnaea, however, perform aerial respiration significantly less often and the three-neuron circuit that drives this behaviour operates significantly differently than in it does in adults. We asked whether these ontogenic behavioural and neurophysiological differences are manifested as an altered ability of juveniles to learn and/or form LTM. We found that juvenile snails learn significantly less well than adults and are, as a group, incapable of forming LTM. To control for the possibility that the poor learning and inability to form memory were the result of juvenile's receiving on average fewer reinforcing stimuli because they perform aerial respiration less often than adults we subjected juveniles to an enforced period of hypoxia to "motivate" juveniles. Motivated juveniles perform aerial respiration as often as adults; yet these "motivated" juveniles continue to be poor learners and still cannot form LTM. Additionally, a small percentage of juveniles perform aerial respiration as often as adults (i.e. high responders). When these "high-responders" were trained they still exhibited poorer learning ability compared with adults and could not form LTM. We conclude that juvenile snails have a more difficult time learning and remembering to suppress aerial respiratory activity than do adults.

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.

Contributions of response set and semantic relatedness to cross-modal Stroop-like picture–word interference in children and adults

Resistance to interference from irrelevant auditory stimuli undergoes development throughout childhood. To test whether semantic processes account for age-related changes in a Stroop-like picture-word interference effect, children (3- to 12-year-olds) and adults named pictures while listening to words varying in terms of semantic relatedness to the pictures and response set membership. In Experiments 1 and 2, with animal and clothing pictures, the interference effect observed in children, but not in adults, depended on the distractors' status as members of the response set. In Experiment 3, with unrelated pictures, adults, but not children, showed greater interference for trials with distractors in the response set. These results indicate developmental changes in picture-word interference involving the establishment of a response set in working memory.

Development of Inhibitory Processing During the Go/NoGo Task

Abstract. The aim of the present study was to investigate behavioral and electrophysiological indices of developing response activation and inhibition processes in child, young-adult, and adult groups. Sixty subjects, with 20 in each of the child (mean age 10.8 years), young-adult (mean age 20.7 years), and older adult (mean age 36.4 years) groups, performed an auditory Go/NoGo task while task performance variables and EEG were recorded. ERPs were derived to Go (response activation) and NoGo (response inhibition) stimuli, with the amplitude and latency of the N1, P2, N2, and P3 ERP components analyzed as a function of age. Results indicate improved task performance, and a reduction in the latency of each component and the amplitude of the N2 and P3 components, with increasing age. Analyses of Go versus NoGo effects indicated differential utilization of inhibition-related processing stages in children compared to adults, with some minor differences between the two adult groups. Go/NoGo effects were evident during early stages of processing, such as those indexed by the N1 and N2 components in children, but only in later stages, as indexed by P3, in adult subjects. This study provides much-needed data on the normative development of response activation and inhibition, as operationalized by the auditory Go/NoGo task, in children and two groups of younger/older adult subjects.

A Meta-Analytic Review of Stopping Performance in Attention-Deficit/Hyperactivity Disorder: Deficient Inhibitory Motor Control?

This review discusses whether deficient inhibitory motor control is the core deficit of attention-deficit/hyperactivity disorder (ADHD). Inhibitory motor control is commonly assessed using the stop-signal paradigm. Since the last meta-analysis that was performed, 33 new studies have appeared. The current meta-analysis revealed a significant difference between ADHD patients and matched controls in stop latency (stop-signal reaction time) in both children and adults. Basic reaction time was significantly longer in children with ADHD, but not in adults, and there was a significant interaction between the elongation of the latency to stop and to respond in adults, but not in children. Deficient inhibitory motor control may be less crucial in children than in adults with ADHD.

Endogenous eye blinks in preadolescents: relationship to information processing and performance

Endogenous blinks--those occurring without apparent provocation--are regulated in adults with respect to the presentation, cognitive loading, and response demands of stimuli. This investigation determined the extent to which similar regulatory and response-related relationships were evident in preadolescents during a visual continuous performance task (CPT). As in adults, increased blink incidence on task, longer blink deferral following stimuli with greater cognitive loading, and blink-facilitated motor responses to imperative stimuli were observed. Reaction times significantly decreased when the button press (BP) occurred near (+/- 200 ms) blink onset and increased across the task period on blink-free but not blink-associated trials. More blinks occurred before motor responses in females, and a reaction time (RT) advantage for males on blink-free trials was maintained across blink-associated conditions. From these results, an interpretation is developed arguing that endogenous blinks are a meaningful and integral component of sensory-motor processing, indexing times of facilitated attentional and motor response capability.