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Distinguishing subcortical and cortical influences in visual attention. Subcortical attentional processing.

PURPOSE: The purpose of the study was to investigate the role of subcortical processing in human visual attention. The midbrain contribution to visual attention is unclear. Although evidence exists for a subcortical attentional advantage in ocular motor tasks, such an advantage has not been shown in perceptual tasks. Because retinotectal projections arise predominantly from nasal retina (i.e., temporal hemifield), subcortical attention should be distributed asymmetrically for monocular viewing conditions with an advantage to the temporal hemifield. METHODS: To test for a subcortical attentional effect, the authors compared the results of binocular and monocular viewing conditions using the split priming motion induction paradigm. In this perceptual attention paradigm, priming cues are presented to the left and right of fixation followed by an instantaneously presented horizontal bar. As a result of attention to the priming cues, motion is perceived within the bar as it appears to draw in from the two lateral cues toward a central collision point. Asymmetrically distributed attention results in an asymmetry in the perception of motion within the bar, and thus the perceived collision point will be shifted away from the center. RESULTS: In two separate studies, one with and one without control of eye movements, the authors found significant differences between the results for monocular and binocular presentation. When the stimulus configuration is presented to the left eye, the perceived collision point is shifted toward the center consistent with a subcortical attentional effect. However, presentation of the stimulus configuration to the right eye yields the same results as those of binocular presentation. CONCLUSIONS: This pattern of results can be explained by a separate and additive interaction between cortical and subcortical attentional effects in the visual field. Dominance of the left visual field for cortical attention and dominance of the temporal visual field for subcortical attention act together when the initial priming cue occurs in the temporal (left) visual field of the left eye. However, these influences compete when the same stimulus configuration is presented to the right eye, where cortical attention predominates in the left visual field and subcortical attention predominates in the temporal (right) visual field.

Adult↗

Methylphenidate-induced improvements of various measures of attention in adults with attention deficit hyperactivity disorder.

The present study examined the effect of the stimulant medication methylphenidate (MPH) on attentional functioning of adults with ADHD. Sixteen adults with a diagnosed ADHD without comorbidity were assessed twice, at baseline off MPH and following MPH treatment. The assessment battery consisted of reaction time tasks of low complexity, including measures of alertness--subdivided into tonic and phasic alertness, vigilance, divided attention, flexibility and such aspects of selective attention as including focused attention, inhibition and integration of sensory information. In addition, 16 healthy participants who were matched to adults with ADHD according to sex, age, education level and intellectual functions were also assessed twice using the same test battery. The results of the present study suggest that adults with ADHD off stimulant medication are seriously impaired in various components of attention including vigilance, divided attention, selective attention and flexibility. These impairments of attention were observed primarily in regard to reaction time and its variability. Treatment of adults with ADHD using individually tailored doses of MPH has a positive effect on measures of alertness, vigilance, selective attention, divided attention and flexibility. However, even on MPH adults with ADHD displayed considerable deficits in vigilance and integration of sensory information. The present findings indicate that adults with ADHD are not differentially impaired in attentional processes but may suffer from a more global deficit of attention. Although MPH treatment has been found to be effective in the treatment of the attention deficit of adults with ADHD, additional treatment appears to be necessary.

Adult↗

Impaired and enhanced attentional function in children with attention deficit/hyperactivity disorder.

BACKGROUND: The symptom domain of inattention in attention deficit/hyperactivity disorder (ADHD) suggests that there are neuropsychological fields of attention in which subjects with ADHD express deficits. However, studies using differentiated neuropsychological attentional tests in ADHD are lacking. METHOD: A consecutive series of 35 subjects with ADHD aged 9-12 years were assessed on a computer-driven neuropsychological test battery for attentional functions. Their performance was classified according to the data of a normative sample of 187 healthy subjects aged 9-12 years, and compared with the performance of 35 matched healthy control subjects. RESULTS: According to normative data, most ADHD subjects performed on all attentional measures within the normal range. Comparisons with the control group revealed that ADHD subjects reacted faster on all attentional tests, yielding statistical significance for the Go/No go test and the Divided Attention test. They also performed with significantly fewer errors on the Divided Attention test. On the Go/No go test, Visual Scanning test and Attentional Shift test ADHD subjects committed significantly more errors than control subjects. CONCLUSIONS: Our results suggest a differential pattern rather than a deficit pattern of attentional functions in ADHD. It is suggested that the more rapid response style of ADHD subjects leads to a more erroneous performance in self-paced attentional tasks and to a better performance in externally paced attentional tasks. However, neuropsychological tests of attention do not contribute to the clinical diagnosis of ADHD.

Attention↗

[Experimental bases for evaluating attention in attention deficit hyperactivity disorder].

INTRODUCTION: The experimental evaluation of the time variable in attention enables us to distinguish between what can be considered as its normal and its pathological behaviour. It has proved to be useful in evaluating the population suffering from attention disorders (attention deficit hyperactivity disorder, frontal lesions, etc.) as a means of defining the extent to which the patient is affected by the disorder and also in designing a training programme for later use. DEVELOPMENT: The most notable attentional paradigms are attentional blink (AB), repetition blindness, change detection, psychological refractory period, task switching, and negative and positive priming. Patients with ADHD showed a poor capacity for identification of target stimuli (T1) in attentional blink tests; they also displayed a significantly higher attentional blink than that observed in the control group, especially for time intervals between 300 and 600 ms after the first target letter (T1). CONCLUSIONS: Attention is a complex, dynamic concept derived from the interaction of different neuroanatomical systems. There are several different theories to explain disorders affecting the attentional skills. One of the explanations comes into being as a result of linking sustained attentional disorder with impulsiveness and hyperactive behaviour. Another is related to selective attention disorders. This distinction allows us to discern the involvement of two systems that will give rise to different clinical symptoms and hence the presence of attentional subtypes. Thus, for example, it is possible to find a first group with disorders affecting attention, impulsiveness and disinhibition, and a second group with slow reactions and in a state of confusion and/or inattention as regards the events taking place around them (but they do not have impulsiveness or disinhibition).

Attention↗

Attention and fluctuating attention in patients with dementia with Lewy bodies and Alzheimer disease.

BACKGROUND: Attentional deficits are described in the consensus clinical criteria for the operationalized diagnosis of dementia with Lewy bodies (DLB) as characteristic of the condition. In addition, preliminary studies have indicated that both attentional impairments and fluctuation of attentional impairments are more marked in patients with DLB than in patients with Alzheimer disease (AD), although neuropsychological function has not previously been examined in a large prospective cohort with confirmed diagnostic accuracy against postmortem diagnosis. METHODS: A detailed evaluation of attention and fluctuating attention was undertaken in 155 patients with dementia (85 with DLB and 80 with AD) from a representative hospital dementia case register and 35 elderly controls using the Cognitive Drug Research Computerized Assessment System for Dementia Patients computerized neuropsychological battery. Operationalized clinical diagnosis was made using the consensus criteria for DLB and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD. High levels of sensitivity and specificity have been achieved for the first 50 cases undergoing postmortem examination. RESULTS: The groups were well matched for severity of cognitive impairments, but the AD patients were older (mean age, 80 vs 78 years) and more likely to be female (55% vs 40%). Patients with DLB were significantly more impaired than patients with AD on all measures of attention and fluctuating attention (for all comparisons, t > or = 2.5, P<.001), and patients from both dementia groups were significantly more impaired than elderly controls for all comparisons other than cognitive reaction time, which was significantly more impaired in DLB patients than controls but was comparable in controls and AD patients. There were, however, significant associations between the severity of cognitive impairment and the severity of both attentional deficits and fluctuations in attention. CONCLUSIONS: This large prospective study confirms that slowing of cognitive processing, attention, and fluctuations of attention are significantly more pronounced in DLB and AD patients, although fluctuating attention is common in patients with moderate-to-severe AD. Deficits of cognitive reaction time appear to be specific to DLB, except in severe dementia. A detailed evaluation of attentional performance could make an important contribution to differential diagnosis, although the results need to be interpreted within the context of the overall severity of cognitive deficits.

Aged↗

More attention must be paid: the neurobiology of attentional effort.

Increases in attentional effort are defined as the motivated activation of attentional systems in response to detrimental challenges on attentional performance, such as the presentation of distractors, prolonged time-on-task, changing target stimulus characteristics and stimulus presentation parameters, circadian phase shifts, stress or sickness. Increases in attentional effort are motivated by the expected performance outcome; in the absence of such motivation, attentional performance continues to decline or may cease altogether. The beneficial effects of increased attentional effort are due in part to the activation of top-down mechanisms that act to optimize input detection and processing, thereby stabilizing or recovering attentional performance in response to challenges. Following a description of the psychological construct "attentional effort", evidence is reviewed indicating that increases in the activity of cortical cholinergic inputs represent a major component of the neuronal circuitry mediating increases in attentional effort. A neuronal model describes how error detection and reward loss, indicating declining performance, are integrated with motivational mechanisms on the basis of neuronal circuits between prefrontal/anterior cingulate and mesolimbic regions. The cortical cholinergic input system is activated by projections of mesolimbic structures to the basal forebrain cholinergic system. In prefrontal regions, increases in cholinergic activity are hypothesized to contribute to the activation of the anterior attention system and associated executive functions, particularly the top-down optimization of input processing in sensory regions. Moreover, and influenced in part by prefrontal projections to the basal forebrain, increases in cholinergic activity in sensory and other posterior cortical regions contribute directly to the modification of receptive field properties or the suppression of contextual information and, therefore, to the mediation of top-down effects. The definition of attentional effort as a cognitive incentive, and the description of a neuronal circuitry model that integrates brain systems involved in performance monitoring, the processing of incentives, activation of attention systems and modulation of input functions, suggest that 'attentional effort' represents a viable construct for cognitive neuroscience research.

Animals↗

Executive function in sleep apnea: controlling for attentional capacity in assessing executive attention.

STUDY OBJECTIVES: As the effects of general slowness and decreased attentional capacity on higher executive attention have not been fully taken into account in the sleep apnea literature, we statistically controlled for basic attentional performance in evaluating executive attention per se in sleep apnea patients. DESIGN: A case-controlled design was used with comparison of basic and executive attentional tasks. PARTICIPANTS: Thirty-six polysomnographically diagnosed patients (mean apnea-hypopnea index = 60.5 +/- SD 31.6) participated, together with 32 healthy controls. MEASUREMENTS AND RESULTS: Neuropsychological tests included Trail Making part A and B, Symbol Digit Modalities (SDMT), Digit Span forward and backward, Stroop Color-Word, Five-Point design fluency, and an Attentional Flexibility task. Patients' vigilance data indicated time-on-task decrements after 10 minutes. Moreover, their performance was significantly reduced on the SDMT (effect size d = 0.93), the Digit Span forward task (d = 0.44), the number of errors on the basic 2-choice reaction time subtest of the Attentional Flexibility task (d = 0.74) and the mean RT on the actual Attentional Flexibility subtest (d = 0.54). It has been argued that the latter poor performance was probably primarily related to the task's phonologic loop component of working memory rather than to an attentional switching deficit per se. No other performance differences were found between patients and healthy controls. CONCLUSIONS: In addition to vigilance decrements, attentional capacity deficits clearly emerge, ie, slowed information processing and decreased short-term memory span. However, no specific clinical indications for executive attentional deficits--such as disinhibition, distractibility, perseveration, attentional switching dysfunction, decreased design fluency, or an impaired central executive of working memory--are found in patients with severe sleep apnea. Their cognitive performance seems very similar to the cognitive decline found after sleep loss and qualitatively different from patients with chronic obstructive pulmonary disease, suggesting sleepiness as the primary factor in a parsimonious explanation for the attention deficits in sleep apnea, without the need to assume prefrontal brain damage.

Attention↗

Effects of transdermal nicotine on attention in adult non-smokers with and without attentional deficits.

Extant evidence suggests a possibility of self-medication to account for greater prevalence of cigarette smoking among adults with ADHD as they tend to show improvements on affective and cognitive measures, particularly on measures of sustained attention following nicotine administration. The present study was conducted to evaluate whether adult non-smokers with low attentiveness might exhibit greater improvements on measures of sustained attention than those with higher attentiveness using neuropsychological tests that had previously shown sensitivity to ADHD. On the basis of their scores on attention scales used in the diagnosis of adult ADHD, 62 male non-smokers were divided into 2 groups of either low or high attentiveness and treated with either a placebo or 7 mg nicotine patch. After 6 h of patch application each participant completed the Wisconsin Card Sorting Test (WCST), classic Stroop task, and Conners' Continuous Performance Test (CPT), which were administered in a counterbalanced order and a double-blind manner. No significant drug or group differences were observed on the Stroop task. On the Conners' CPT participants in the low attention group treated with nicotine committed significantly fewer errors of commission, showed improved stimulus detectability and fewer perseverations than those in the low attention placebo group. On the WCST nicotine significantly impaired the ability of participants in the high attention group to learn effective strategies to complete the test with fewer trials. The results showed nicotine-induced improvement on some measures of sustained attention in the low attention group and some decrement in working memory in the high attention group, which suggests that nicotine tends to optimize rather than improve performance on cognitive tasks.

Administration, Cutaneous↗

Attention processes in children with shunted hydrocephalus versus attention deficit-hyperactivity disorder.

Children with congenital hydrocephalus, children with attention deficit-hyperactivity disorder, and normal controls were evaluated with measures of focused attention (Visual Orienting and Detection Task), sustained attention (continuous performance test), and attention shifting (Wisconsin Card Sorting Test). Components from these tasks have been linked to attention systems mediated by anterior or posterior brain networks. Children with congenital hydrocephalus showed an inability to focus and shift attention, which specifically implicated impairment of the disengage and move components of the posterior brain attention system. Children with attention deficit-hyperactivity disorder displayed the expected performance patterns on measures of focused attention once their difficulties with sustained attention were taken into account. However, they showed problems with shifting and sustaining attention, which are commonly associated with the anterior brain attention system.

Achievement↗

Time course of attention reveals different mechanisms for spatial and feature-based attention in area V4.

Attention can facilitate visual processing, emphasizing specific locations and highlighting stimuli containing specific features. To dissociate the mechanisms of spatial and feature-based attention, we compared the time course of visually evoked responses under different attention conditions. We recorded from single neurons in area V4 during a delayed match-to-sample task that controlled both spatial and feature-based attention. Neuronal responses increased when spatial attention was directed toward the receptive field and were modulated by the identity of the target of feature-based attention. Modulation by spatial attention was weaker during the early portion of the visual response and stronger during the later portion of the response. In contrast, modulation by feature-based attention was relatively constant throughout the response. It appears that stimulus onset transients disrupt spatial attention, but not feature attention. We conclude that spatial attention reflects a combination of stimulus-driven and goal-driven processes, while feature-based attention is purely goal driven.

Animals↗

The differential assessment of children's attention: the Test of Everyday Attention for Children (TEA-Ch), normative sample and ADHD performance.

"Attention" is not a unitary brain process. Evidence from adult studies indicates that distinct neuroanatomical networks perform specific attentional operations and that these are vulnerable to selective damage. Accordingly, characterising attentional disorders requires the use of a variety of tasks that differentially challenge these systems. Here we describe a novel battery, the Test of Everyday Attention for Children (TEA-Ch), comprising nine subtests adapted from the adult literature. The performance of 293 healthy children between the ages of 6 and 16 is described together with the relationships to IQ, existing measures of attention, and scholastic attainment. This large normative sample also allows us to test the fit of the adult model of functionally separable attention systems to the observed patterns of variance in children's performance. A Structural Equation Modelling approach supports this view. A three-factor model of sustained and selective attention and higher-level "executive" control formed a good fit to the data, even in the youngest children. A single factor model was rejected. There are behavioural and anatomical grounds to believe that Attention Deficit Disorder (ADD) is particularly associated with poor self-sustained attention and behavioural control. The TEA-Ch performance of 24 boys diagnosed with ADD presented here is consistent with this view. When performance levels on WISC-III subtests were taken into account, specific deficits in sustained attention were apparent while selective attention performance was within the normal range.

Activities of Daily Living↗

Reorienting attention across the horizontal and vertical meridians: evidence in favor of a premotor theory of attention.

Stimuli presented in a non-attended location are responded to much slower than stimuli presented in an attended one. The hypotheses proposed to explain this effect make reference to covert movement of attention, hemifield inhibition, or attentional gradients. The experiment reported here was aimed at discriminating among these hypotheses. Subjects were cued to attend to one of four possible stimulus locations, which were arranged either horizontally or vertically, above, below, to the right or left of a fixation point. The instructions were to respond manually as fast as possible to the occurrence of a visual stimulus, regardless of whether it occurred in a cued or in a non-cued location. In 70% of the cued trials the stimulus was presented in the cued location and in 30% in one of the non-cued locations. In addition there were trials in which a non-directional cue instructed the subject to pay attention to all four locations. The results showed that the correct orienting of attention yielded a small but significant benefit; the incorrect orienting of attention yielded a large and significant cost; the cost tended to increase as a function of the distance between the attended location and the location that was actually stimulated; and an additional cost was incurred when the stimulated and attended locations were on opposite sides of the vertical or horizontal meridian. We concluded that neither the hypothesis postulating hemifield inhibition nor that postulating movement of attention with a constant time can explain the data. The hypothesis of an attention gradient and that of attention movements with a constant speed are tenable in principle, but they fail to account for the effect of crossing the horizontal and vertical meridians. A hypothesis is proposed that postulates a strict link between covert orienting of attention and programming explicit ocular movements. Attention is oriented to a given point when the oculomotor programme for moving the eyes to this point is ready to be executed. Attentional cost is the time required to erase one ocular program and prepare the next one.

Attention↗

Spatial attention in agenesis of the corpus callosum: shifting attention between visual fields.

The role of the corpus callosum in spatially selective visual attention is uncertain. Research using commissurotomy and callosotomy patients has attempted to determine if the corpus callosum plays a role in reorienting attention between visual fields, as if spatial attention is unitary or divisible between the cerebral hemispheres. Reorienting of selective visuospatial attention within versus between visual fields was tested in 10 individuals with agenesis of the corpus callosum (ACC) and nine matched controls. Spatially focused attention to the most likely location of target appearance was created using both peripheral sensory cues and central symbolic cues in separate tests. Results demonstrated that individuals with ACC have significantly greater difficulty reorienting attention to an invalidly cued target stimulus occurring in the opposite visual field. However, this effect did not interact with the type of cueing (sensory or symbolic). Individuals with ACC did not differ from controls either with respect to the laterality of within-field reorientation of attention, or with respect to the most efficient direction of between-field shifting of attention. Since congenital absence of the corpus callosum significantly reduces efficiency in the reorienting of attention between visual fields, spatial attention cannot be completely unified based on a subcortical mechanism and the mobilization of attentional resources within each hemisphere must depend on callosal processes.

Adult↗

The attentional role of the left parietal cortex: the distinct lateralization and localization of motor attention in the human brain.

It is widely agreed that visuospatial orienting attention depends on a network of frontal and parietal areas in the right hemisphere. It is thought that the visuospatial orienting role of the right parietal lobe is related to its role in the production of overt eye movements. The experiments reported here test the possibility that other parietal regions may be important for directing attention in relation to response modalities other than eye movement. Specifically, we used positron emission tomography (PET) to test the hypothesis that a 'left' parietal area, the supramarginal gyrus, is important for attention in relation to limb movements (Rushworth et al., 1997; Rushworth, Ellison, & Walsh, in press). We have referred to this process as 'motor attention' to distinguish it from orienting attention. In one condition subjects spent most of the scanning period covertly attending to 'left' hand movements that they were about to make. Activity in this first condition was compared with a second condition with identical stimuli and movement responses but lacking motor attention periods. Comparison of the conditions revealed that motor attention-related activity was almost exclusively restricted to the 'left' hemisphere despite the fact that subjects only ever made ipsilateral, left-hand responses. Left parietal activity was prominent in this comparison, within the parietal lobe the critical region for motor attention was the supramarginal gyrus and the adjacent anterior intraparietal sulcus (AIP), a region anterior to the posterior parietal cortex identified with orienting attention. In a second part of the experiment we compared a condition in which subjects covertly rehearsed verbal responses with a condition in which they made verbal responses immediately without rehearsal. A comparison of the two conditions revealed verbal rehearsal-related activity in several anterior left hemisphere areas including Broca's area. The lack of verbal rehearsal-related activity in the left supra-marginal gyrus confirms that this area plays a direct role in motor attention that cannot be attributed to any strategy of verbal mediation. The results also provide evidence concerning the importance of ventral premotor (PMv) and Broca's area in motor attention and language processes.

Adult↗

Where and when to pay attention: the neural systems for directing attention to spatial locations and to time intervals as revealed by both PET and fMRI.

Although attention is distributed across time as well as space, the temporal allocation of attention has been less well researched than its spatial counterpart. A temporal analog of the covert spatial orientation task [Posner MI, Snyder CRR, Davidson BJ (1980) Attention and the detection of signals. J Exp Psychol Gen 109:160-174] was developed to compare the neural systems involved in directing attention to spatial locations versus time intervals. We asked whether there exists a general system for allocating attentional resources, independent of stimulus dimension, or whether functionally specialized brain regions are recruited for directing attention toward spatial versus temporal aspects of the environment. We measured brain activity in seven healthy volunteers by using positron emission tomography (PET) and in eight healthy volunteers by using functional magnetic resonance imaging (fMRI). The task manipulated cued attention to spatial locations (S) and temporal intervals (T) in a factorial design. Symbolic central cues oriented subjects toward S only (left or right), toward T only (300 msec or 1500 msec), toward both S and T simultaneously, or provided no information regarding S or T. Subjects also were scanned during a resting baseline condition. Behavioral data showed benefits and costs for performance during temporal attention similar to those established for spatial attention. Brain-imaging data revealed a partial overlap between neural systems involved in the performance of spatial versus temporal orientation of attention tasks. Additionally, hemispheric asymmetries revealed preferential right and left parietal activation for spatial and temporal attention, respectively. Parietal cortex was activated bilaterally by attending to both dimensions simultaneously. This is the first direct comparison of the neural correlates of attending to spatial versus temporal cues.

Adult↗

Attentional blink in adults with attention-deficit hyperactivity disorder. Influence of eye movements.

The attentional blink paradigm tests attention by overloading it: a list of stimuli is presented very rapidly one after another at the same location on a computer screen, each item overwriting the last, and participants monitor the list using two criteria [e.g. detect the target (red letter) and identify the probe (letter p)]. If the interval between the target and the probe is greater than about 500 ms, both are usually reported correctly, but, when the interval between the target and the probe is within 200-500 ms, report of the probe declines. This decline is the attentional blink, an interval of time when attention is supposedly switching from the first criterion to the second. The attentional blink paradigm should be difficult to perform correctly without vigilantly attending to the rapidly presented list. Vigilance tasks are often used to assess attention-deficit hyperactivity disorder (ADHD). Symptoms of the disorder include hyperactivity and attentional dysfunction; however, some people with ADHD also have difficulty maintaining gaze at a fixed location. We tested 15 adults with ADHD and their age- and sex-matched controls, measuring accuracy and gaze stability during the attentional blink task. ADHD participants reported fewer targets and probes, took longer to recover from the attentional blink, made more eye movements, and made identification errors consistent with non-perception of the letter list. In contrast, errors made by control participants were consistent with guessing (i.e., report of a letter immediately preceding or succeeding the correct letter). Excessive eye movements result in poorer performance for all participants; however, error patterns confirm that the weak performance of ADHD participants may be related to gaze instability as well as to attentional dysfunction.

Adult↗

Cognitive processes in children's reading and attention: the role of working memory, divided attention, and response inhibition.

Children experiencing attention difficulties have documented cognitive deficits in working memory (WM), response inhibition and dual tasks. Recent evidence suggests however that these same cognitive processes are also closely associated with reading acquisition. This paper therefore explores whether these variables predicted attention difficulties or reading among 123 children with and without significant attention problems sampled from the school population. Children were screened using current WM and attention task measures. Three factors explained variance in WM and attention tasks. Response inhibition tasks loaded mainly with central executive measures, but a dual processing task loaded with the visual-spatial WM measures. Phonological loop measures loaded independently of attention measures. After controls for age, IQ and attention-group membership, phonological loop and 'central processing' measures both predicted reading ability. A 'visual memory/dual-task' factor predicted attention group membership after controls for age, IQ and reading ability. Results thus suggest that some of the processes previously assumed to be predictive of attention problems may reflect processes involved in reading acquisition. Visual memory and dual-task functioning are, however, purer indices of cognitive difficulty in children experiencing attention problems.

Attention↗

Effect of psychostimulants on distinct attentional parameters in attentional deficit/hyperactivity disorder.

Although there is extensive literature about the effects of stimulants on sustained attention tasks in attentional deficit/hyperactivity disorder (ADHD), little is known about the effect of these drugs on other attentional tasks involving different neural systems. In this study we measured the effect of stimulants on ADHD children, both in the electroencephalographic (EEG) activity during sustained attentional tasks and in psychometric performance during selective attentional tasks. These tasks are known to rely on different cortical networks. Our results in children medicated with 10 mg of d-amphetamine administered 60 min before the study indicate (i) a significant increase in amplitude but not latency of the P300 component of the event-related potential (ERP) during the sustained attentional task and (ii) a significant improvement in the reaction times and correct responses in the selective attentional task. In addition to supporting the use of stimulants in children with attentional deficit/hyperactivity disorder, these results show a multifocal activity improvement of cortical structures linked to dopamine, and interestingly, to attention. All these analyses are framed in a wider study of diverse attentional functions in this syndrome.

Adolescent↗