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At least 1,063 records · Page 59Linked to original sources
PubMed2000

Reflexive joint attention depends on lateralized cortical connections.

Joint attention, the tendency to spontaneously direct attention to where someone else is looking, has been thought to occur because eye direction provides a reliable cue to the presence of important events in the environment. We have discovered, however, that adults will shift their attention to where a schematic face is looking--even when gaze direction does not predict any events in the environment. Research with 2 split-brain patients revealed that this reflexive joint attention is lateralized to a single hemisphere. Moreover, although this phenomenon could be inhibited by inversion of a face, eyes alone produced reflexive shifts of attention. Consistent with recent functional neuroimaging studies, these results suggest that lateralized cortical connections between (a) temporal lobe subsystems specialized for processing upright faces and gaze and (b) the parietal area specialized for orienting spatial attention underlie human reflexive shifts of attention in response to gaze direction.

Adult↗
PubMed2002

Visual attention and coactivation of response decisions for features from different dimensions.

The role of visual attention in task performance has been extensively debated. On the basis of the dimensional-action model, we hypothesized that a major role of attention is to transfer response decisions from targets on which it is focused to high-level centers dealing with response execution. This hypothesis predicts that response decisions for two targets will interact only when attention is focused on both targets, and only when the response to the targets is defined by different dimensions. Three experiments, using the redundancy-gain paradigm, tested and confirmed this prediction. Experiment 1 showed that coactivation of two cross-dimensional targets occurred only when the targets were positioned in the same location, not when they were in separate locations. Experiment 2 manipulated the focus of attention and showed that coactivation can occur even for targets positioned in different locations if they are both within the attentional focus. Experiment 3 showed that this attention-induced coactivation does not occur for targets from the same dimensional module. These results suggest that a major role of attention is postperceptual and involves gating of selected responses to executive functions.

Attention↗
PubMed2003

Transient spatial attention degrades temporal resolution.

To better understand the interplay between the temporal and spatial components of visual perception, we studied the effects of transient spatial attention on temporal resolution. Given that spatial attention sharpens spatial resolution, can it also affect temporal resolution? To assess temporal resolution, we measured the two-flash fusion threshold When two flashes of light are presented successively to the same location, the two-flash fusion threshold is the minimal interval between the flashes at which they are still perceived as two flashes, rather than a single flash. This assessment of temporal resolution was combined with peripheral precuing--a direct manipulation of transient spatial attention. This allowed us to demonstrate, for the first time, that spatial attention can indeed affect temporal resolution. However, in contrast to its effect on spatial resolution, spatial attention degrades temporal resolution. Two attentional mechanisms that could account for both attentional effects--enhanced spatial resolution and reduced temporal resolution--are discussed.

Attention↗
PubMed2003

Anterior and posterior attentional control systems use different spatial reference frames: ERP evidence from covert tactile-spatial orienting.

To investigate whether processes controlling preparatory covert shifts of spatial attention operate within external and anatomically defined spatial coordinates, lateralized event-related potentials components sensitive to the direction of attentional shifts were measured in response to visual precues directing attention to the relevant location of tactile events. Participants had to detect infrequent tactile targets delivered to the hand located on the cued side. In different blocks, hands were uncrossed or crossed, so that external and anatomical codes specifying task-relevant locations were either congruent or incongruent. With uncrossed hands, an anterior directing attention negativity and a posterior directing attention positivity were elicited in the cue-target interval contralateral to the side of a cued attentional shift. Although the posterior effect was unaffected by hand posture, the anterior effect was delayed and reversed polarity with crossed relative to uncrossed hands. This pattern of results provides new evidence that different spatial coordinate systems may be used by separable attentional control processes. It is suggested that a posterior process operates on the basis of external spatial coordinates, whereas an anterior process is based primarily on anatomically defined spatial codes.

Adult↗
PubMed2002

Temporal dynamics of lateralized ERP components elicited during endogenous attentional shifts to relevant tactile events.

To investigate the temporal dynamics of lateralized event-related brain potential (ERP) components elicited during covert shifts of spatial attention, ERPs were recorded in a task where central visual symbolic cues instructed participants to direct attention to their left or right hand in order to detect infrequent tactile targets presented to that hand, and to ignore tactile stimuli presented to the other hand, as well as all randomly intermingled peripheral visual stimuli. In different blocks, the stimulus onset asynchrony (SOA) between cue and target was 300 ms, 700 ms, or 1,100 ms. Anterior and posterior ERP modulations sensitive to the direction of an attentional shift were time-locked to the attentional cue, rather than to the anticipated arrival of a task-relevant stimulus. These components thus appear to reflect central attentional control rather than the anticipatory preparation of sensory areas. In addition, attentional modulations of ERPs to task-irrelevant visual stimuli were found, providing further evidence for crossmodal links in spatial attention between touch and vision.

Adult↗
PubMed2005

Do new objects capture attention?

The visual system relies on several heuristics to direct attention to important locations and objects. One of these mechanisms directs attention to sudden changes in the environment. Although a substantial body of research suggests that this capture of attention occurs only for the abrupt appearance of a new perceptual object, more recent evidence shows that some luminance-based transients (e.g., motion and looming) and some types of brightness change also capture attention. These findings show that new objects are not necessary for attention capture. The present study tested whether they are even sufficient. That is, does a new object attract attention because the visual system is sensitive to new objects or because it is sensitive to the transients that new objects create? In two experiments using a visual search task, new objects did not capture attention unless they created a strong local luminance transient.

Attention↗
PubMed2004

Central blockade of muscarinic cholinergic receptors disrupts affective and attentional set-shifting.

Impairments in multiple aspects of attentional and executive function follow damage to cholinergic neurons in the central nervous system. Affective and attentional set-shifting represent two aspects of executive function controlled by different sectors of the prefrontal cortex. The involvement of cholinergic neural mechanisms in these aspects of executive function has not been specified. To determine whether central muscarinic cholinergic receptors were involved in affective and/or attentional set-shifting, we tested rats on a series of discrimination learning problems, which included affective (reversal learning) and attentional set (extradimensional shift)-shifting components, under the systemic influence of scopolamine, a muscarinic antagonist. Scopolamine impaired both reversal learning and extradimensional shifting, but was without effect on learning new discrimination problems that did not require an affective or attentional shift. Systemic administration of methylscopolamine, which does not cross the blood-brain barrier, did not impair affective or attentional set-shifting, indicating that the scopolamine effects were centrally mediated. These data implicate muscarinic receptors in the central nervous system in the control of executive function. Taken together with other recent data, they may also suggest an important role for cholinergic receptors outside of the neocortex in regulating these aspects of attention and executive function.

Animals↗
PubMed2004

Long-term but not short-term blockade of dopamine release in Drosophila impairs orientation during flight in a visual attention paradigm.

Dopamine is a major neuromodulator in both vertebrates and invertebrates and has profound effects on many physiological processes, including the regulation of attention. Most studies of the functions of dopamine use models with long-term blockade of dopamine release and few effects of transient blockade have yet been reported. The goal of the present study was to determine the role of dopamine in attention-like behavior in Drosophila by taking advantage of the fly's orientation behavior during flight. The examination of several different transgenic flies in a single-target visual attention paradigm showed that flies lost their orientation ability if dopamine release was blocked from the beginning of the development of dopaminergic neurons. This is similar to the attention loss in mammals. However, if the blockade of dopamine release was induced during the experimental procedure, flies performed normally. Statistical analysis of the behavioral assessment showed a significant difference between long-term and transient blockade. Using the RNA interference approach, we generated flies with down-regulated J-domain protein, which is a potential cochaperone in synaptic vesicle release, to make an alternative form of long-term dopamine-blockade mutant. Behavioral assays revealed that flies with permanent J-domain protein down-regulation specifically in dopaminergic neurons have an attention defect similar to that induced by long-term blockade of dopamine release. Furthermore, dopamine depletion beginning at eclosion also caused an attention deficit. Our results indicate that prolonged but not transient blockade of dopamine release impairs visual attention-like behavior in Drosophila.

Animals↗
PubMed2004

Attention and executive function deficits in chronic low-dose MPTP-treated non-human primates.

Parkinson's disease (PD) is a complex disorder consisting of motor deficits coupled with dysfunction in cognitive domains that are dependent upon the integrity of the frontal lobes and/or the fronto-striatal axis. Although it is increasingly acknowledged that PD patients have attentional and executive function deficits, it has been difficult to model these in nonhuman primates because of the nature of the cognitive tasks that have been used previously. The present studies were conducted to further define the nature of the cognitive impairment in a nonhuman primate model of early parkinsonism consequent to chronic low dose MPTP exposure and to further validate this model in monkeys trained to perform a battery of attentional and executive function tasks. Following chronic low dose MPTP exposure, monkeys developed deficits in maintenance of a response set as well problems in shifting attentional sets, suggesting decreased mental flexibility. On other tasks inattentiveness, an impaired ability to sustain spatial attention or to focus attention, a deficit in motor readiness and planning, and impaired time estimation were also observed. These results provide direct evidence of attention and executive function deficits in a nonhuman primate model of early parkinsonism. Based on these findings, we suggest that in addition to being useful for studying the cognitive deficits related to early PD and for developing new therapeutics for these problems, this model and these testing procedures may also provide a useful large animal model for studying attention deficit disorder and for developing new therapeutics for that condition as well.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2006

Attentional functioning is impaired during acute hypoglycaemia in people with Type 1 diabetes.

AIMS: To examine the effects of acute insulin-induced hypoglycaemia on different aspects of attention and on general non-verbal reasoning in people with Type 1 diabetes. METHODS: A hyperinsulinaemic glucose clamp was used to maintain euglycaemia (4.5 mmol/l) or induce hypoglycaemia (2.6 mmol/l) on separate occasions in 16 adults with Type 1 diabetes each of whom were studied on two occasions in a counterbalanced order. During each study condition, the subjects completed parallel tests of cognitive function assessed by the Test of Everyday Attention and the Raven's Progressive Matrices. RESULTS: Hypoglycaemia caused a significant deterioration in tests sensitive to visual and auditory selective attention. During hypoglycaemia, attentional flexibility deteriorated and speed of information processing was delayed. Sustained attention and intelligence scores were preserved during hypoglycaemia. CONCLUSIONS: In people with Type 1 diabetes, hypoglycaemia causes a significant deterioration in attentional abilities, while non-verbal reasoning is preserved. It is likely therefore that many complex cognitive tasks which involve attention will be impaired during moderate hypoglycaemia during everyday life.

Acute Disease↗
PubMed2004

Impaired disengagement of attention in young children with autism.

BACKGROUND: The present study examined the disengage and shift operations of visual attention in young children with autism. METHODS: For this purpose, we used a simple visual orienting task that is thought to engage attention automatically. Once attention was first engaged on a central fixation stimulus, a second stimulus was presented on either side, either simultaneously or successively. Latency to begin an eye movement to the peripheral stimulus served as the main dependent measure. The two stimulus conditions (simultaneous and successive) provided independent measures of disengaging and shifting attention, respectively. Performance of children with autism was compared to that of children with Down syndrome and a normal group. RESULTS: The main finding was that relative to both comparison groups, children with autism had marked difficulty in disengaging attention. Indeed, on 20% of trials they remained fixated on the first of two competing stimuli for the entire 8-second trial duration. Evidence is also provided for a more subtle problem in executing rapid shifts of attention. CONCLUSIONS: Our findings on disengagement in autism parallel those reported in normal 2-month-olds, in whom attention has been described as 'obligatory'. Discussion focuses on the potential role of general versus domain-specific processes in producing some of the core features of autism.

Attention↗
PubMed1995

Neural mechanisms of visual selective attention.

Visual selective attention improves our perception and performance by modifying sensory inputs at an early stage of processing. Spatial attention produces the most consistent early modulations of visual processing, which can be observed when attention is voluntarily allocated to locations. These effects of spatial attention are similar when attention is cued in a trial-by-trial, or sustained, fashion and are manifest as changes in the amplitudes, but not the latencies, of evoked neural activity recorded from the intact human scalp. This modulation of sensory processing first occurs within the extrastriate visual cortex and not within the striate or earlier subcortical processing stages. These relatively early spatial filters alter the inputs to higher stages of visual analysis that are responsible for feature extraction and ultimately object perception and recognition, and thus provide physiological evidence for early precategorical selection during visual attention. Moreover, the physiological evidence extends early selection theories by providing neurophysiologically precise information about the stages of visual processing affected by attention.

Arousal↗
PubMed2006

Varieties of attention in neutral trials: linking RT to ERPs and EEG frequencies.

It is often assumed that when a neutral cue is presented in a spatial cueing task, attention remains at fixation until target onset. We hypothesized that variance in nonspatial attention and switches of attention toward target locations can account for variance in reaction times of neutral trials. Lateralized event-related potentials (ERPs) and changes in electroencephalogram (EEG) frequency bands served as predictor variables in a single-trial logistic regression analysis to predict the direction of spatial attention in cued and neutral trials. The contingent negative variation (CNV) and non-lateralized changes in the alpha band served as markers of nonspatial attention. The direction of attention in cued trials was reliably predicted from single-trial lateralized ERP components. In neutral trials, only evidence for nonspatial attention was found, indicated by increases in the CNV and decreases in alpha preceding targets to which responses were relatively fast.

Adult↗
PubMed1999

Attentional ability among survivors of leukaemia.

Attentional ability in 19 survivors of acute lymphoblastic leukaemia and 19 sibling controls was assessed using a neuropsychological model of attention. Analysis revealed that children who had received treatment for leukaemia exhibited significantly poorer performance on measures of the "focus encode" and "focus execute" elements of attention and on measures of the ability to respond to external cues and feedback. No significant differences in performance were found for measures of sustained attention and the ability to shift attention. These results indicate that children who have received treatment for leukaemia may experience highly specific attentional deficits that could have an impact on academic performance, particularly mathematical and reading skills. It is suggested that this underlying attentional deficit might be the source of the neuropsychological sequelae associated with the disease. Future attempts at remediation should incorporate activities specifically designed to ameliorate focusing difficulties.

Antineoplastic Agents↗
PubMed2003

Attentional ability among survivors of leukaemia treated without cranial irradiation.

BACKGROUND: Previous research has indicated that children who have received treatment for leukaemia which includes cranial irradiation exhibit deficits in their ability to focus attention. It has been suggested that the use of cranial irradiation may have a role to play in long term sequelae. AIMS: To investigate neuropsychological functioning among children treated for leukaemia without cranial irradiation. METHODS: In a cross sectional study, 17 leukaemic patients and their sibling controls were assessed using a neuropsychological model of attention. All were treated on the UKALL XI protocol and none had received cranial irradiation. Participants completed the Arithmetic subtest and Digit Span subtest of the Weschler Intelligence Scale for Children-Revised to assess focus-encode elements of attention; the Coding subtest and the Speed of Information subtest of the BAS to assess focus-execute aspects of attention; the VIGIL computerised battery to assess sustain elements of attention; and the Wisconsin Card Sorting test to assess the ability to shift attention. RESULTS: These children did not exhibit the deficits witnessed in previous cohorts, and were performing at comparable levels to their controls on all measures of attention CONCLUSIONS: These findings suggest that children who have received treatment for leukaemia without the use of cranial irradiation do not show the neuropsychological insult found in earlier treatment groups.

Attention↗
PubMed1990

Contralateral and ipsilateral disorders of visual attention in patients with unilateral brain damage.

To explain the prevalence of unilateral spatial neglect in patients with right brain damage, Heilman et al have suggested that the attentional neurons of the right parietal lobe might have bilateral receptive fields, whereas the homologous cells of the left hemisphere would have strictly contralateral receptive fields. One implication of this theory is that patients with right brain damage should show a prevalence of disorders of visual attention not only in the half space contralateral to the damaged hemisphere, but also in the ipsilateral one. To check this theory, 50 control subjects, 102 right and 125 left brain-damaged patients were given a drawing completion task in which patients were requested to complete the missing parts of a star, a cube and a house. Omissions of lines lying on the sides of the models contralateral and ipsilateral to the damaged hemisphere were taken separately into account. Results did not confirm the hypothesis, since right brain-damaged patients failed to complete the contralateral sides of the models much more frequently than patients with left brain injury, but no difference was found between the two hemispheric groups when ipsilateral disorders of visual attention were taken into account. Furthermore, no correlation was found between omissions of lines lying on the sides of the models contralateral and ipsilateral to the damaged hemisphere. This finding suggests that contralateral and ipsilateral disorders of visual attention are not due to the same mechanism in right brain-damaged patients. The alternative hypothesis viewing ipsilateral disorders as resulting from a widespread lowering of general attention (and only contralateral neglect reflecting a specific disorder of visual attention) was supported by results obtained on a verbal memory test, used to evaluate the general cognitive and attention level of the patients. Patients with clear-cut ipislateral inattention obtained very low scores on this test, whereas patients with severe contralateral neglect, but not ipislateral inattention scored within the normal range on the verbal memory test.

Attention↗
PubMed2001

Perception, attention, and working memory are disproportionately impaired in dementia with Lewy bodies compared with Alzheimer's disease.

OBJECTIVE: To test the hypotheses that visuoperceptual and attentional ability are disproportionately impaired in patients having dementia with Lewy Bodies (DLB) compared with Alzheimer's disease (AD). METHODS: A comprehensive battery of neuropsychological tasks designed to assess working, episodic, and semantic memory, and visuoperceptual and attentional functions was given to groups of patients with DLB (n=10) and AD (n=9), matched for age, education, and mini mental state examination (MMSE), and to normal controls (n=17). RESULTS: Both patient groups performed equally poorly on tests of episodic and semantic memory with the exception of immediate and delayed story recall, which was worse in the AD group. Digit span was by contrast spared in AD. The most striking differences were on tests of visuoperceptual/spatial ability and attention. Whereas patients with AD performed normally on several subtests of the visual object and space perception battery, the DLB group showed substantial impairments. In keeping with previous studies, the AD group showed deficits in selective attention and set shifting, but patients with DLB were more impaired on virtually every test of attention with deficits in sustained, selective, and divided attention. CONCLUSIONS: Patients with DLB have substantially greater impairment of attention, working memory, and visuoperceptual ability than patients with AD matched for overall dementia severity. Semantic memory seems to be equally affected in DLB and AD, unlike episodic memory, which is worse in AD. These findings may have relevance for our understanding of the genesis of visual hallucinations, and the differential diagnosis of AD and DLB.

Aged↗
PubMed2001

The development of visual attention in infancy.

Over the past decade, the study of attention in infancy has seen dramatic progress. This review delineates four attentional functions (alertness, spatial orienting, attention to object features, and endogenous attention) that are relevant to infancy and uses these functions as a framework for summarizing the developmental course of attention in infancy. Rudimentary forms of various attentional functions are present at birth, but each of the functions exhibits different and apparently dissociable periods of postnatal change during the first years of life. The role of attention in development should therefore be considered in the context of interaction among different systems at different levels of maturity during the first years of life.

Arousal↗