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PubMed2005

Impaired sustained attention and error awareness in traumatic brain injury: implications for insight.

The processes of error awareness and sustained attention were investigated in 18 traumatic brain injury (TBI) individuals and 16 matched control participants. In Experiment 1, we found that: (1) in comparison to controls, TBI participants displayed reduced sustained attention and awareness of error during the Sustained Attention to Response Task; (2) degree of error awareness was strongly correlated with sustained attention capacity, even with severity of injury partialed out; and (3) that error feedback significantly reduced errors. We replicated the finding of a correlation between error awareness and sustained attention capacity in Experiment 2 with a separate sample of 19 TBI participants and 20 controls. We conclude that TBI leads to impaired sustained attention and error awareness. The finding of a significant relationship between these two deficits in TBI suggests there may be a link between these two processes. Feedback on error improves sustained attention performance of control and TBI participants.

Adolescent↗
PubMed2006

Cognitive remediation in ADHD: effects of periodic non-contingent alerts on sustained attention to response.

Few studies have attempted direct cognitive remediation of attention deficits in attention-deficit hyperactivity disorder (ADHD). The present study investigated the efficacy of periodic non-informative alerting cues for improving sustaining attention in ADHD. This technique is known to improve sustained attention in right frontal injury patients and may be effective in ADHD, given that this disorder has also been linked with right frontal dysfunction. Fifteen children with ADHD and 15 matched controls completed four blocks of a modified version of the Sustained Attention to Response Task (SART). Eight random non-contingent alerts were introduced on two of these blocks as a cue for participants to adopt a more supervisory stance to their performance. While the alerting cues did not alter the total number of commission errors committed by ADHD children over a task block, they did produce a significant short-term reduction in commission errors in the period immediately following an alerting cue. Our data demonstrate that sustained attention performance can be enhanced in children with ADHD using a simple cognitive training strategy. Methods from the field of cognitive rehabilitation may be viably applied to the remediation of attention deficits in ADHD.

Adolescent↗
PubMedDate not supplied

The diversity of attention deficits in ADHD: the prevalence of four cognitive factors in ADHD versus controls.

The performance of participants with attention-deficit/hyperactivity disorder (ADHD) relative to control participants was measured on four tasks uniquely assessing the functions of selective attention, executive attention, sustained attention, and orienting of attention. The results showed that deficits in sustained attention were the most pronounced, characterizing most participants with ADHD and deficits in each of the other three functions characterized more than half of these participants. Different participants with ADHD revealed different clusters of attentional deficits. These results call for a revision of leading theories of ADHD that identify the core of the pathology as a sole deficit in executive functions.

Attention↗
PubMed2006

Fundamentals of attention-deficit/hyperactivity disorder: circuits and pathways.

Neuropsychological and imaging studies have shown that attention-deficit/hyperactivity disorder (ADHD) is associated with alterations in prefrontal cortex (PFC) and its connections to striatum and cerebellum. Research in animals, in combination with observations of patients with cortical lesions, has shown that the PFC is critical for the regulation of behavior, attention, and affect using representational knowledge. The PFC is important for sustaining attention over a delay, inhibiting distraction, and dividing attention, while more posterior cortical areas are essential for perception and the allocation of attentional resources. The PFC in the right hemisphere is especially important for behavioral inhibition. Lesions to the PFC produce a profile of distractibility, forgetfulness, impulsivity, poor planning, and locomotor hyperactivity. The PFC is very sensitive to its neurochemical environment, and optimal levels of norepinephrine and dopamine are needed for proper PFC control of behavior and attention. Recent electrophysiologic studies in animals suggest that norepinephrine enhances "signals" through postsynaptic alpha2A-adrenoceptors in PFC, while dopamine decreases "noise" through modest levels of D1-receptor stimulation. Blockade of alpha2-receptors in the monkey PFC re-creates the symptoms of ADHD, resulting in impaired working memory, increased impulsivity, and locomotor hyperactivity. Genetic alterations in catecholamine pathways may contribute to dysregulation of PFC circuits in this disorder. Stimulant medications may have some of their therapeutic effects by increasing endogenous stimulation of alpha2A-adrenoceptors and dopamine D1-receptors in the PFC, optimizing PFC regulation of behavior and attention.

Animals↗
PubMed2002

Disruption of neural systems of visual attention in schizophrenia.

BACKGROUND: Patients with schizophrenia show attention deficits. The frontal P2a and posterior N2b event-related potential components are early indices of activity in neural systems supporting attention and they are reduced in schizophrenia in auditory tasks. However, the auditory P300 is reduced as well. Thus, the P2a and N2b reductions may simply reflect a general event-related potential amplitude reduction. The visual P300, however, is often spared in schizophrenia. If neural systems supporting attention are specifically disrupted in schizophrenia, the attention-sensitive P2a and N2b should be differentially reduced in patients, compared with the P300, in a visual attention task. METHODS: We analyzed 64-channel event-related potentials from 14 schizophrenic patients and 14 control subjects in a visual object-spatial attention task. We examined the amplitude of the P2a, N2b, and P300 components in the target minus standard difference wave to see if there was a differential reduction of the P2a and N2b compared with the P300. RESULTS: Both the P2a and N2b waveforms were reduced in the patient group (81% [control mean, 1.99 microV; patient mean, 0.38 microV] and 95% [control mean, 0.55 microV; patient mean, 0.03 microV], respectively) while the P300 was not reduced. Measured at the peak of the frontal P2a, the N2b was larger dorsally in the spatial task and larger ventrally in the object task in the control group. CONCLUSIONS: The spatial distribution of the P2a and N2b was consistent with activity in the prefrontal cortex and modality-specific posterior cortex, respectively. The differential reduction of the P2a and N2b waveforms supports the hypothesis of specific disruption in neural systems of visual attention in schizophrenia.

Adult↗
PubMed2007

Abnormal attention modulation of fear circuit function in pediatric generalized anxiety disorder.

CONTEXT: Considerable work implicates abnormal neural activation and disrupted attention to facial-threat cues in adult anxiety disorders. However, in pediatric anxiety, no research has examined attention modulation of neural response to threat cues. OBJECTIVE: To determine whether attention modulates amygdala and cortical responses to facial-threat cues differentially in adolescents with generalized anxiety disorder and in healthy adolescents. DESIGN: Case-control study. SETTING: Government clinical research institute. PARTICIPANTS: Fifteen adolescents with generalized anxiety disorder and 20 controls. MAIN OUTCOME MEASURES: Blood oxygenation level-dependent signal as measured via functional magnetic resonance imaging. During imaging, participants completed a face-emotion rating task that systematically manipulated attention. RESULTS: While attending to their own subjective fear, patients, but not controls, showed greater activation to fearful faces than to happy faces in a distributed network including the amygdala, ventral prefrontal cortex, and anterior cingulate cortex (P<.05, small-volume corrected, for all). Right amygdala findings appeared particularly strong. Functional connectivity analyses demonstrated positive correlations among the amygdala, ventral prefrontal cortex, and anterior cingulate cortex. CONCLUSIONS: This is the first evidence in juveniles that generalized anxiety disorder-associated patterns of pathologic fear circuit activation are particularly evident during certain attention states. Specifically, fear circuit hyperactivation occurred in an attention state involving focus on subjectively experienced fear. These findings underscore the importance of attention and its interaction with emotion in shaping the function of the adolescent human fear circuit.

Adolescent↗
PubMed1997

Attention, coping, and activity in children undergoing orthopaedic surgery.

The purpose of this study was to determine how children's preoperative focus of attention on the stresses of surgery related to their preoperative coping and return to usual activities during recovery. Children's attention was classified according to three different foci: concrete-objective, emotion, and vague. Children (N = 97) between the ages of 8 and 17 years who were undergoing major orthopaedic surgery participated in the study. Data were collected the day before surgery, and at 3, 6, and 9 months postoperatively. Children who focused on the concrete-objective aspects of surgery had the most positive activity outcomes, followed by the emotion-focused attention group. Children who were classified as having vague focused attentions had the least favorable activity outcomes. When there were significant coping by attention interaction effects, vigilant copers who had a concrete-objective focus of attention had the most favorable activity outcomes at each time of measurement. Children who were able to focus their attention on concrete aspects of the experience tended to use vigilant coping and were able to return to their usual activities sooner.

Activities of Daily Living↗
PubMed2004

Automatic attention to emotional stimuli: neural correlates.

We investigated the capability of emotional and nonemotional visual stimulation to capture automatic attention, an aspect of the interaction between cognitive and emotional processes that has received scant attention from researchers. Event-related potentials were recorded from 37 subjects using a 60-electrode array, and were submitted to temporal and spatial principal component analyses to detect and quantify the main components, and to source localization software (LORETA) to determine their spatial origin. Stimuli capturing automatic attention were of three types: emotionally positive, emotionally negative, and nonemotional pictures. Results suggest that initially (P1: 105 msec after stimulus), automatic attention is captured by negative pictures, and not by positive or nonemotional ones. Later (P2: 180 msec), automatic attention remains captured by negative pictures, but also by positive ones. Finally (N2: 240 msec), attention is captured only by positive and nonemotional stimuli. Anatomically, this sequence is characterized by decreasing activation of the visual association cortex (VAC) and by the growing involvement, from dorsal to ventral areas, of the anterior cingulate cortex (ACC). Analyses suggest that the ACC and not the VAC is responsible for experimental effects described above. Intensity, latency, and location of neural activity related to automatic attention thus depend clearly on the stimulus emotional content and on its associated biological importance.

Adult↗
PubMed1993

Modulation of the directional attention deficit in visual neglect by hemispatial factors.

Using a visuo-spatial cuing paradigm, Posner and collaborators (Posner, Cohen, & Rafal, 1982; Posner, Walker, Friedrich, & Rafal, 1984) reported that subjects with a parietal lobe lesion have difficulty in disengaging their visual attention from an invalidly precued location in the ipsilesional hemifield when the target they have to respond to is presented in the contralesional field. Later, these authors (Posner, Walker, Friedrich, & Rafal, 1987) proposed that this disengagement deficit is one involving spatial shifts of attention in a contralesional direction, irrespective of the visual hemifield in which the target is presented. This proposal of a directional disengagement deficit along the horizontal axis, present in either hemifield, contrasts with a report by Baynes, Holtzman, & Volpe (1986) showing, in right parietal subjects, a disengagement deficit for shifts of attention along the vertical axis that is only manifest in the contralesional hemifield. In the present report, we assessed the disengagement deficit of a neglect subject along the horizontal and vertical axes. Results show a disengagement deficit restricted to shifts of attention in the contralesional direction (horizontal axis), which is significant only in the contralesional visual hemifield. However, there is a clear trend for a directional disengagement deficit in the ipsilateral field. These observations indicate that the attention deficit present in neglect is directional and is modulated either by hemispatial factors or by the lateral target location in the visual field. On the basis of the present results, it is proposed that the deficit of parietal subjects may best be conceptualized as one of attentional capture for stimuli located on the contralesional side of the current focus of attention rather than one of disengagement.

Aged↗
PubMed2001

Focused and nonfocused attention in verbal and emotional dichotic listening: an FMRI study.

Functional magnetic resonance imaging (fMRI) was used to identify cortical regions which are involved in two dichotic listening tasks. During one task the subjects were required to allocate attention to both ears and to detect a specific target word (phonetic task), while during a second task the subjects were required to detect a specific emotional tone (emotional task). During three attentional conditions of each task, the subjects were required to focus attention to the right (FR) or left ear (FL), while during a third condition subjects were required to allocate attention to both ears simultaneously. In 11 right-handed male subjects, these dichotic listening tasks evoked strong activations in a temporofrontal network involving auditory cortices located in the temporal lobe and prefrontal brain regions. Hemodynamic responses were measured in the following regions of interest: Heschl's gyrus (HG), the planum polare (PP), the planum temporale (PT), the anterior superior temporal sulcus (aSTS), the posterior superior temporal sulcus (pSTS), and the inferior frontal gyrus region (IFG) of both hemispheres. The following findings were obtained: (1) the degree of activation in HG and PP depends on the direction of attention. In particular it was found that selectively attending to right-ear input led to increased activity specifically in the left HG and PP and attention to left ear input increased right-sided activity in these structures; (2) hemodynamic responses in the PT, aSTS, pSTS, and IFG were not modulated by the different focused-attention conditions; (3) hemodynamic responses in HG and PP in the nonforced conditions were the sum activation of the forced conditions; (4) there was no general difference between the phonetic and emotion tasks in terms of hemodynamic responses; (5) hemodynamic responses in the PT and pSTS were strongly left-lateralized, reflecting the specialization of these brain regions for language processing. These findings are discussed in the context of current theories of hemispheric specialization.

Adult↗
PubMedDate not supplied

Attention, awareness, and the triangular circuit.

It is proposed that attention to an object requires the simultaneous activity of three brain regions that are interconnected by a triangular circuit. The regions are the cortical site of attentional expression, the thalamic enhancement structure, and the prefrontal area of control. It is also proposed that awareness of an object requires the additional component of attention directed to a representation of the self. The expression of attention to a self-representation may involve activations of cortical sites corresponding to the body landscape and/or verbal-based memories of autobiographical episodes. As in the case of attention to objects, attention to the self is presumed to involve a triangular circuit. The proposed triangular circuit of attention is shown to be generally consistent with current knowledge of brain structures and with data from a broad range of experiments concerned with the functions of neurons in these structures.

Attention↗
PubMed1997

The functional neuroanatomy of awareness: with a focus on the role of various anatomical systems in the control of intermodal attention.

This review considers a number of recent theories on the neural basis of consciousness, with particular attention to the theories of Bogen, Crick, Llinás, Newman, and Changeux. These theories allot different roles to various key brain areas, in particular the reticular and intralaminar nuclei of the thalamus and the cortex. Crick's hypothesis is that awareness is a function of reverberating corticothalamic loops and that the spotlight of intramodal attention is controlled by the reticular nucleus of the thalamus. He also proposed different mechanisms for attention and intention ("will"). The current review presents a new hypothesis, based on elements from these hypotheses, including intermodal attention and olfaction and pain, which may pose problems for Crick's original theory. This work reviews the possible role in awareness and intermodal attention and intention of the cholinergic system in the basal forebrain and the tegmentum; the reticular, the intralaminar, and the dorsomedial thalamic nuclei; the raphe and locus coeruleus; the reticular formation; the ventral striatum and extended amygdala; insula cortex, and other selected cortical, areas. Both clinical and basic research data are covered. The conclusion is reached that the brain may work by largely nonlinear parallel processing and much intramodal shifts of attention may be effected by intracortical, or multiple corticothalamic mechanisms (small local "flashlights" rather than one major "searchlight"). But this is constrained by the functional anatomy of the circuits concerned and waking "awareness" is modulated by the many "nonspecific" systems (cholinergic from the basal forebrain, noradrenergic from the locus coeruleus, dopaminergic from the substantia nigra and ventral tegmentum, and serotoninergic from the raphe). But the principal agents for intermodal attention shifts, the "searchlight," may be two key nuclei of the cholinergic system in the mesencephalon. Clinical loss of consciousness results from damage to these nuclei but not from damage to the cholinergic nucleus basalis of the basal forebrain.

Attention↗
PubMed1998

Mental-attentional capacity: does cognitive style make a difference?

There is currently no consensus on whether the difference between field-dependent and field-independent subjects on tasks of cognitive abilities result from different mental processing strategies, from true group differences in cognitive ability, or from both. School-age children (N = 239) were tested for field dependence/independence using the Children's Embedded Figures Test and for mental-attentional capacity using the Figural Intersection Task. Multigroup scaling models were used to separate the contributions of style from ability in children's performance on Figural Intersection items. Results show that field-dependent children have greater odds of success than field-independent children in Figural Intersection items when the task's mental-attentional demand is above the child's mental attentional capacity, as assessed in the same task. The contrary is true when the task's mental-attentional demand is below or equal to the mental-attentional capacity of the child. Overall, field-dependent children obtain lower estimates of mental-attentional capacity than field-independent children in this task. We discuss the implications of these results for the measurement of mental-attentional capacity and the conceptualization of field dependence/independence.

Adolescent↗
PubMed2001

Location- or feature-based targeting of peripheral attention.

Using event-related fMRI we determined the differential effects of feature- versus location-based cues for directing peripheral attention. Pairs of same-color targets appeared on the left and on the right. A predictive cue indicated whether the subsequent targeting of attention would be based on location (left versus right) or color (red versus blue). Subjects had to press a button when the relevant pair of targets (in the cued side of space or of the cued color) were identical in shape. The feature-based cue thus also led to a "global" expectancy of targets on either side of space whereas the location-based cue elicited a more "focal" expectancy limited to one side of space. The right inferior parietal lobule was more active when attention was targeted on the basis of location than of color. There was no difference between left-sided or right-sided attention in this region, indicating that it mediated the targeting to both sides of space. These results show that the right inferior parietal cortex plays a relatively selective role in mediating location-based and spatially focal modes of attentional deployment. Its relatively equal activation for leftward and rightward attentional shifts is also consistent with models of right hemispheric dominance of spatial attention.

Adult↗
PubMed2001

Do we need the "lateral" in unilateral neglect? Spatially nonselective attention deficits in unilateral neglect and their implications for rehabilitation.

This paper reviews evidence that the spatial imbalance of attention by which unilateral neglect is often defined is a necessary but not sufficient factor in the persistence of this disorder. A second, nonspatially lateralized loss of attentional capacity is required to coexist with the spatial bias for the disorder to persist in a clinically significant way, it is argued. To this end, I first review evidence from visual and auditory attention studies to show that unilateral neglect is very strongly associated with a fundamental loss of attentional capacity that is not confined to one region of space. Second, I attempt to characterize the nature of this attentional capacity in relation in particular to functional brain imaging studies of attention. Third, I demonstrate that the spatial imbalance in neglect can be reduced by manipulations of the nonlateralized attentional capacity and finish by reviewing the rehabilitation implications of these manipulations.

Attention↗
PubMed1995

Independent contributions of the orienting of attention, fixation offset and bilateral stimulation on human saccadic latencies.

In a series of experiments we examined the effects of the endogenous orienting of visual attention on human saccade latency. Three separate manipulations were performed: the orienting of visual attention, the prior offset of fixation (gap paradigm) and the bilateral presentation of saccade targets. Each of these manipulations was shown to make an independent contribution to saccade latency. In experiments 1 and 2 subjects were instructed to orient their attention covertly to a location by a verbal pre-cue; targets could appear in the attended hemifield (valid) or in the non-attended hemifield (invalid) together with a no-instruction (neutral) condition. Saccades were made under fixation gap and overlap conditions, to either single target or two bilaterally presented targets which appeared at equal and opposite eccentricities in both hemifields. The results showed a large increase (cost) of saccade latency to invalid targets and a small non-significant decrease (benefit) of saccade latency to valid targets. The cost associated with invalid targets replicates the "meridan crossing effect" shown in manual reaction time experiments and is consistent with the hemifield inhibition and premotor models of attentional orienting. The use of a "gap" procedure produced a generalised facilitation of saccade latency, which was not modified by the prior orienting of visual attention. The magnitude of the gap effect was similar for saccades made to attended and non-attended stimulis. This suggests that the gap effect may be due to ocular motor disengagement, or a warning signal effect, rather than to the prior disengagement of visual attention. When two targets were presented simultaneously, one in each hemifield, saccade latency was slowed compared with the single target condition. The magnitude of this slowing was unaffected by the prior orienting of visual attention or by the fixation condition. The slowing was examined in more detail in experiment 3, by presenting targets with brief offset delays. The latency increase was maximal if the two targets were presented simultaneously and decreased if the distractor appeared at short intervals (20-80 ms) before or after the saccade target onset. If the non-attended stimulus was presented at greater intervals (160, 240 ms) before the saccade target, then a facilitation effect was observed. This demonstrates that the onset of a distractor in the non-attended hemifield can have both an inhibitory and a facilitatory effect on a saccade production.

Attention↗
PubMed1993

The role of attention for the Simon effect.

It has been claimed that spatial attention plays a decisive role in the effect of irrelevant spatial stimulus-response correspondence (i.e., the Simon effect), especially the way the attentional focus is moved onto the stimulus (lateral shifting rather than zooming). This attentional-movement hypothesis is contrasted with a referential-coding hypothesis, according to which spatial stimulus coding depends on the availability of frames or objects of reference rather than on certain attentional movements. In six experiments, reference objects were made available to aid spatial coding, which either appeared simultaneously with the stimulus (Experiments 1-3), or were continuously visible (Experiments 4-6). In contrast to previous experiments and to the attentional predictions, the Simon effect occurred even though the stimuli were precued by large frames surrounding both possible stimulus positions (Experiment 1), even when the reference object's salience was markedly reduced (Experiment 2), or when the precueing frames were made more informative (Experiment 3). Furthermore, it was found that the Simon effect is not reduced by spatial correspondence between an uninformative spatial precue and the stimulus (Experiment 4), and it does not depend on the location of spatial precues appearing to the left or right of both possible stimulus locations (Experiment 5). This was true even when the precue was made task-relevant in order to ensure attentional focusing (Experiment 6). In sum, it is shown that the Simon effect does not depend on the kind of attentional operation presumably performed to focus onto the stimulus. It is argued that the available data are consistent with a coding approach to the Simon effect which, however, needs to be developed to be more precise as to the conditions for spatial stimulus coding.

Adult↗
PubMed1991

A pattern of test findings predicting attention problems at school.

The aim of this study was to identify different types of neuropsychological test profiles that would predict attention problems at school. Forty-six children with mild developmental disorders, among whom a high frequency of attention deficit disorder (ADD) was expected, were examined just before they started school. The tests were mainly drawn from a new assessment, called NEPSY, and corresponded to the various components of attention. The test profiles were grouped with the aid of a Q-type factor analysis into five subgroups. The test profiles of two of the subgroups were suggestive of attention deficits. The predictions were based on difficulties in tests aimed to evaluate impulse control, sustained attention, and selective attention. As such findings were found in both of the subgroups they were collapsed into one. Half a year later the collapsed subgroups were found to have a higher frequency of attention problems at school than the other three subgroups.

Attention Deficit Disorder with Hyperactivity↗