Which aspects of visual attention are changed by deafness? The case of the Attentional Network Test

The loss of one sensory modality can lead to a reorganization of the other intact sensory modalities. In the case of individuals who are born profoundly deaf, there is growing evidence of changes in visual functions. Specifically, deaf individuals demonstrate enhanced visual processing in the periphery, and in particular enhanced peripheral visual attention. To further characterize those aspects of visual attention that may be modified by deafness, deaf and hearing individuals were compared on the Attentional Network Test (ANT). The ANT was selected as it provides a measure of the efficiency of three neurally distinct subsystems of visual attention: alerting, orienting and executive control. The alerting measure refers to the efficiency with which a temporal cue is used to direct attention towards a target event, and the orienting measure is an indicator of the efficiency with which a spatial cue focuses attention upon that target's spatial location. The executive control measure, on the other hand, is an indicator of the amount of interference from peripheral flankers on processing that central target. In two separate experiments, deaf and hearing individuals displayed similar alerting and orienting abilities indicating comparable attention across populations. As predicted by enhanced peripheral attention, deaf subjects were found to have larger flanker interference effects than hearing subjects. These results indicate that not all aspects of visual attention are modified by early deafness, suggesting rather specific effects of cross-modal plasticity.     

Effects of transcranial direct current stimulation over right posterior parietal cortex on attention function in healthy young adults

Attention involves three distinct networks for alerting, orienting, and executive control. Interventions targeting the specific attentional networks remain lacking. Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability, which potentially serves as an interventional tool to treat individuals with attention impairment. The purpose of this study was to examine the effects of applying tDCS over the right posterior parietal cortex (PPC) on the performance of the three attentional networks. Twenty‐six healthy young adults performed the Attention Network Test before and after anodal or sham tDCS stimulation over the right PPC. The alerting, orienting, and executive effects were assessed before and after the stimulation. The results demonstrated that the orienting effect was significantly improved after real tDCS relative to sham, whereas the alerting and executive control effects remained unaffected. Consistent with previous clinical and functional imaging studies, this suggests that the right PPC is actively engaged with the spatial orienting of attention.     

Presentation modality influences behavioral measures of alerting, orienting, and executive control.

The Attention Network Test (ANT) uses visual stimuli to separately assess the attentional skills of alerting (improved performance following a warning cue), spatial orienting (an additional benefit when the warning cue also cues target location), and executive control (impaired performance when a target stimulus contains conflicting information). This study contrasted performance on auditory and visual versions of the ANT to determine whether the measures it obtains are influenced by presentation modality. Forty healthy volunteers completed both auditory and visual tests. Reaction-time measures of executive control were of a similar magnitude and significantly correlated, suggesting that executive control might be a supramodal resource. Measures of alerting were also comparable across tasks. In contrast, spatial-orienting benefits were obtained only in the visual task. Auditory spatial cues did not improve response times to auditory targets presented at the cued location. The different spatial-orienting measures could reflect either separate orienting resources for each perceptual modality, or an interaction between a supramodal orienting resource and modality-specific perceptual processing.     

Threat-related attentional biases: an analysis of three attention systems

It is unclear how threat-related attentional biases affect multiple attention systems. This study used a new modification of a reaction time paradigm to examine whether inter-trial task-irrelevant fearful faces influenced the efficiency of alerting, orienting, and executive attention, and whether effects varied with level of state anxiety. Participants, 63 non-disordered adults (17 males and 46 females), reported on their subjective state anxiety and completed a modified version of the Attention Network Test in which fearful or neutral faces or control stimuli were presented briefly (50 ms) between trials of the task, but provided no task-relevant information. Across all participants, state anxiety was positively correlated with alerting, whereas fearful versus neutral faces were linked to decreased alerting efficiency. Contrasting high and low anxiety groups showed that fearful versus neutral faces reduced executive attention in the low state anxiety group only, suggesting decreased distraction by irrelevant stimuli in the high state anxiety group. Results document threat-related attentional biases that varied with attention system but failed to find enhanced bias effects among those with higher state anxiety in a typical range. This modification of the Attention Network Test, which added presentation of emotional distracters, provides a potentially useful new method for assessing the impact of task-irrelevant emotional stimuli on three aspects of attention performance.     

Testing the efficiency and independence of attentional networks

In recent years, three attentional networks have been defined in anatomical and functional terms. These functions involve alerting, orienting, and executive attention. Reaction time measures can be used to quantify the processing efficiency within each of these three networks. The Attention Network Test (ANT) is designed to evaluate alerting, orienting, and executive attention within a single 30-min testing session that can be easily performed by children, patients, and monkeys. A study with 40 normal adult subjects indicates that the ANT produces reliable single subject estimates of alerting, orienting, and executive function, and further suggests that the efficiencies of these three networks are uncorrelated. There are, however, some interactions in which alerting and orienting can modulate the degree of interference from flankers. This procedure may prove to be convenient and useful in evaluating attentional abnormalities associated with cases of brain injury, stroke, schizophrenia, and attention-deficit disorder. The ANT may also serve as an activation task for neuroimaging studies and as a phenotype for the study of the influence of genes on attentional networks.     

局灶性脑损伤患者注意网络功能受损的特点

目的 研究局灶性脑损伤患者注意网络功能受损的特点,探讨额叶、顶叶、颞叶与3个独立的注意网络功能的关系.方法 应用注意网络测验,测试23例额叶损伤、18例颞叶损伤和18例顶叶损伤患者以及53名健康对照的注意网络功能.结果 与对照组相比,额叶损伤组的执行控制网络效率显著减低,额叶损伤组、对照组分别为(143.7±46.6)、(91.6±46.4)ms,Z值为-4.714,P＜0.01;而顶、颞叶损伤组的执行控制网络效率的差异尤统计学意义;顶叶损伤组的定向网络效率显著减低,顶叶损伤组、对照组分别为(34.9±25.2)、(55.1±21.8)ms,Z=-2.418,P＜0.05;额叶损伤组的定向网络效率增高,额叶损伤组、对照组分别为(71.2±35.2)、(55.1±21.8)ms,Z=-2.125,P＜0.05;而颞叶损伤组的定向网络效率的差异无统计学意义;额、顶、颞叶损伤组的警觉网络效率与对照组相比差异均无统计学意义.结论 神经心理学证据提示,额叶与执行控制功能密切相关,顶叶在注意的定向网络中起关键作用,而颞叶损伤患者的注意网络功能基本不受影响.     

Common and specific impairments in attention functioning in girls with chromosome 22q11.2 deletion,fragile X or Turner syndromes

Background

Chromosome 22q11.2 deletion syndrome (22q11.2DS), fragile X syndrome (FXS), and Turner syndrome (TS) are complex and variable developmental syndromes caused by different genetic abnormalities; yet, they share similar cognitive impairments in the domains of numbers, space, and time. The atypical development of foundational neural networks that underpin the attentional system is thought to result in further impairments in higher-order cognitive functions. The current study investigates whether children with similar higher-order cognitive impairments but different genetic disorders also show similar impairments in alerting, orienting, and executive control of attention.

Methods

Girls with 22q11.2DS, FXS, or TS and typically developing (TD) girls, aged 7 to 15 years, completed an attention network test, a flanker task with alerting and orienting cues. Exploration of reaction times and accuracy allowed us to test for potential commonalities in attentional functioning in alerting, orienting, and executive control. Linear regression models were used to test whether the predictors of group and chronological age were able to predict differences in attention indices.

Results

Girls with 22q11.2DS, FXS, or TS demonstrated unimpaired function of the alerting system and impaired function of the executive control system. Diagnosis-specific impairments were found such that girls with FXS made more errors and had a reduced orienting index, while girls with 22q11.2DS showed specific age-related deficits in the executive control system.

Conclusions

These results suggest that the control but not the implementation of attention is selectively impaired in girls with 22q11.2DS, TS or FXS. Additionally, the age effect on executive control in girls with 22q11.2DS implies a possible altered developmental trajectory.     

Biasing the organism for novelty: A pervasive property of the attention system

Although the functional and anatomical independences between the orienting and the executive attention networks have been well established, surprisingly little is known about the potential neural interaction between them. Recent studies point out that spatial inhibition of return (IOR), a mechanism associated with the orienting network, and nonspatial inhibition of return, a mechanism associated with the executive network, might bias the organism for novel locations and objects, respectively. By orthogonally combining the spatial and the nonspatial IOR paradigms in this fMRI study, we demonstrate that the orienting and the executive networks interact and compensate each other in biasing the attention system for novelty. Behaviorally, participants responded slower to the target at the old location only when the color of the target was novel, and participants responded slower to the old color representation only when the target appeared at a novel spatial location. Neurally, the orienting network was involved in slowing down responses to the old location only when the nonspatial IOR mechanism in the executive network was not operative (i.e., when the color of the target was novel); the prefrontal executive network was involved in slowing down responses to the old color representation only when the spatial IOR mechanism in the orienting network was not functioning (i.e., when the target appeared at a novel location). Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.     

Selective impairments of alerting and executive control in HIV-infected patients: evidence from attention network test

Background

Attention ability can be subdivided into three functionally independent networks, i.e., alerting network, orienting network, and executive network. Previous literature has documented that deficits in attention are a common consequence of HIV infection. However, the precise nature of deficits of attention in HIV-infected patients is poorly understood. Accordingly, the aim of the study was to identify whether the HIV-infected patients showed a specific attention network deficit or a general attentional impairment.

Methods

We investigated 27 HIV-infected patients and 31 normal controls with the Attention Network Test (ANT).

Results

The patients exhibited less efficient alerting network and executive network than controls. No significant difference was found in orienting network effect between groups. Our results also indicate a tendency for poorer efficiency on alerting attention and executive attention in patients with CD4 ≤ 200.

Conclusions

Our findings suggest that HIV-infected patients exhibited selective impairments of attention network of alerting and executive control. The link between lower CD4 T cell count and poorer attention network function imply the importance of starting antiretroviral therapy earlier to avoid irreversible neurocognitive impairment.

     

小脑损伤患者28例注意网络功能受损的特点

目的 研究小脑损伤患者注意网络功能受损的特点.方法 应用注意网络测验,对28例小脑损伤患者和31名健康对照进行注意网络功能的测试.结果 与对照组相比,小脑损伤患者定向效率减低[病例组、对照组分别为(36.32±30.58)、(54.39±22.17)ms],差异有统计学意义(Z=-2.309,P＜0.05);执行控制受到损害[(160.05±83.25)、(93.42±37.41)ms],差异有统计学意义(Z=-3.500,P＜0.01);警觉效率[(35.14±45.59)、(28.81±26.09)ms]与总平均反应时[(797.14±94.11)、(739.90±97.90)ms]的差异无统计学意义.病例组的总平均错误率(6.57%±9.84%)明显高于对照组(3.38%±5.42%,Z=-2.119,P＜0.05).结论 小脑参与了注意网络的认知功能;小脑病变可选择性损害注意网络的定向和执行控制功能,而警觉功能相对保持正常.     

Attentional network deficits in children with autism spectrum disorder

Statement of purpose: Individuals with autism spectrum disorder (ASD) often demonstrate deficient attentional ability, but the specific nature of the deficit is unclear. The Attention Networks model provides a useful approach to deconstruct this attentional deficit into its component parts. Method: Fifty-two neurotypical (NT) children and 14 children with ASD performed the child version of the Attention Network Test (ANT). The latter requires participants to indicate the direction of a centre target stimulus, which is presented above/below fixation and sometimes flanked by either congruent or incongruent distractor stimuli. Results: Relative to NT children, those with ASD were: (1) slower to react to spatially cued trials and (2) more error prone on executive (conflict) attention trials. Conclusions: Young children with ASD have intact alerting attention, but less-efficient orienting and executive attention.     

The effect of focused attention and open monitoring meditation on attention network function in healthy volunteers

Mindfulness meditation techniques are increasingly popular both as a life-style choice and therapeutic adjunct for a range of mental and physical health conditions. However, little is known about the mechanisms through which mindfulness meditation and its constituent practices might produce positive change in cognition and emotion. Our study directly compared the effects of Focused Attention (FA) and Open-Monitoring (OM) meditation on alerting, orienting and executive attention network function in healthy individuals. Participants were randomized to three intervention groups: open-focused meditation, focused attention, and relaxation control. Participants completed an emotional variant of the Attention Network Test (ANT) at baseline and post-intervention. OM and FA practice improved executive attention, with no change observed in the relaxation control group. Improvements in executive attention occurred in the absence of change in subjective/self-report mood and cognitive function. Baseline levels of dispositional/trait mindfulness were positively correlated with executive control in the ANT at baseline. Our results suggest that mindfulness meditation might usefully target deficits in executive attention that characterise mood and anxiety disorders.     

Plasma neuropeptide Y: a biomarker for symptom severity in chronic fatigue syndrome

Background

Attention deficits belong to the main cognitive symptoms of schizophrenia and come along with altered neural activity in previously described cerebral networks. Given the high heritability of schizophrenia the question arises if impaired function of these networks is modulated by susceptibility genes and detectable in healthy risk allele carriers.

Methods

The present event-related fMRI study investigated the effect of the single nucleotide polymorphism (SNP) rs1018381 of the DTNBP1 (dystrobrevin-binding protein 1) gene on brain activity in 80 subjects while performing the attention network test (ANT). In this reaction time task three domains of attention are probed simultaneously: alerting, orienting and executive control of attention.

Results

Risk allele carriers showed impaired performance in the executive control condition associated with reduced neural activity in the left superior frontal gyrus [Brodmann area (BA) 9]. Risk allele carriers did not show alterations in the alerting and orienting networks.

Conclusions

BA 9 is a key region of schizophrenia pathology and belongs to a network that has been shown previously to be involved in impaired executive control mechanisms in schizophrenia. Our results identified the impact of DTNBP1 on the development of a specific attention deficit via modulation of a left prefrontal network.     

Development of attention networks in deaf children: Support for the integrative hypothesis

Early auditory deprivation is known to affect visual attention, yet the early effects of auditory deprivation on visual attention cannot be described simply as deficiencies or enhancements, because selected aspects of visual attention could be modified in various ways along the developmental trajectory. However, few studies have explored the development of these various aspects of visual attention in deaf children. In this paper we study the developmental trajectory of three aspects of visual attention (alerting, orienting and executive control attention networks) in a group of deaf children between 6 and 12 years of age. We used the attention network test to explore the development of the three attention networks and a child-friendly version of the cost–benefit paradigm to characterize the development of the basic operations of orienting. Our results showed a pattern of specific but varied outcomes with respect to the effects of auditory deprivation on these attention networks. First, auditory deprivation can impair development of the alerting network. Second, auditory deprivation can enhance two elementary operations of orienting: moving and engaging. Third, the executive control network showed a developmental trajectory that was neither deficient nor enhanced, but rather similar to that observed with hearing children. Taken together, these results are consistent with the integrative hypothesis of the effects of auditory deprivation on visual attention.     

Covert and overt orienting to gaze direction cues and the effects of fixation offset

We examined covert and overt orienting in response to non-predictive gaze direction cues and investigated whether the subcortical superior colliculus (SC) plays a role in this type of orienting. Participants viewed a centrally presented gazing schematic face and responded to targets appearing at gazed-at or non-gazed-at locations either by making a keypress response while maintaining central fixation or by making an eye movement to the target. For both response conditions, the fixation stimulus (the gazing face) either remained on the screen or was extinguished at the time of target presentation, a manipulation known to engage and disengage the SC. Results revealed that participants making manual responses oriented covertly to the gazed-at location regardless of the fixation condition, and that participants making eye movements oriented overtly only if the fixation stimulus remained on the screen. Overt gaze-triggered orienting was not enhanced relative to covert orienting, and the fixation offset effect was not reduced for averted gaze cues relative to straight gaze cues. These findings suggest that gaze direction cues do not activate or predisengage the oculomotor system, and thus that orienting to gaze direction does not engage the SC. This is consistent with the view that gaze-triggered orienting is a unique form of reflexive orienting that depends crucially on cortical processes.     

Neural correlates of attentional deficits in Parkinson's disease patients with mild cognitive impairment

IntroductionDeficits in attentional processing observed in Parkinson's disease (PD) patients with mild cognitive impairment (MCI) increase risk of PD dementia. However, the neural basis of these attentional deficits are presently unknown. The present study aimed to explore the neural correlates of attention dysfunction in PD-MCI using the Attention Network Test (ANT) and functional Magnetic Resonance Imaging (fMRI).MethodFifteen (15) PD-MCI patients, 26 PD patients without MCI (PD-NC) and 22 healthy controls (HC) were scanned (3T Siemens PRISMA) whilst performing the ANT. Reaction time, accuracy and fMRI BOLD activation were compared between groups for the three attentional task components of 1) alerting, 2) orienting, and 3) executive control.ResultsPD-MCI patients showed an overall slower reaction time compared to PD-NC and HC, and showed less interference of reaction time in the orienting effect than HC. fMRI data demonstrated greater activation in the bilateral cerebellum crus 1 during the alerting attention condition in both PD-MCI and PD-NC compared to HC. However, activation was supressed in the left postcentral gyrus in PD-MCI compared to PD-NC and HC.DiscussionAlterations in the alerting attention functional network despite intact task performance in PD-MCI suggests that functional brain changes may precede cognitive changes in the attention domain. Furthermore, increased activation in the cerebellum may reflect an attentional compensatory mechanism unique to the PD pathology. Taken together, the findings suggest that PD has a complex effect on attentional ability that can, at least in part, be elucidated using functional neuroimaging.     

Neural correlates of the attention network test in schizophrenia

Attentional deficits are prominent in schizophrenia, affecting nearly all cognitive functions. Human attention comprises three essential components: alerting, orienting and executive control. For the assessment of these functions, the attention network test (ANT) has been proposed and used in healthy controls and patients. In schizophrenia, the ANT has revealed behavioral deficits; however, the corresponding neural correlates have not been examined. In the present study, neural correlates of attention were investigated in 17 schizophrenia patients and 17 healthy controls using the ANT with fMRI. Behavioral deficits emerged in the alertness system with a reduced efficiency for temporal cues. In fMRI, changes were observed for all three domains-alerting, orienting and conflict-and revealed hyper- as well as hypoactivation in patients. Affected regions during alerting comprised a broad fronto-temporo-parieto-occipito-cerebellar network, while differences during orienting mainly tapped fronto-parietal regions and during conflict processing a thalamo-frontal-temporal occipital network including the postcentral regions. In general, hyperactivations were positively correlated with more severe psychopathologial symptoms.     

Does attention bias modification improve attentional control? A double-blind randomized experiment with individuals with social anxiety disorder

People with anxiety disorders often exhibit an attentional bias for threat. Attention bias modification (ABM) procedure may reduce this bias, thereby diminishing anxiety symptoms. In ABM, participants respond to probes that reliably follow non-threatening stimuli (e.g., neutral faces) such that their attention is directed away from concurrently presented threatening stimuli (e.g., disgust faces). Early studies showed that ABM reduced anxiety more than control procedures lacking any contingency between valenced stimuli and probes. However, recent work suggests that no-contingency training and training toward threat cues can be as effective as ABM in reducing anxiety, implying that any training may increase executive control over attention, thereby helping people inhibit their anxious thoughts. Extending this work, we randomly assigned participants with DSM-IV diagnosed social anxiety disorder to either training toward non-threat (ABM), training toward threat, or no-contingency condition, and we used the attention network task (ANT) to assess all three components of attention. After two training sessions, subjects in all three conditions exhibited indistinguishably significant declines from baseline to post-training in self-report and behavioral measures of anxiety on an impromptu speech task. Moreover, all groups exhibited similarly significant improvements on the alerting and executive (but not orienting) components of attention. Implications for ABM research are discussed.     

Principal component analysis of behavioural individual differences suggests that particular aspects of visual working memory may relate to specific aspects of attention

The previously separate literatures on visual attention and on visual working memory are converging, with growing interest in how visual attention may relate to visual short-term memory, as exemplified by this special issue. We report exploratory analysis of how individual behavioural differences in separable aspects of attention may relate to particular aspects of visual working memory. Previous work with the Attention Network Test (ANT; Fan, McCandliss, Sommer, Raz, & Posner, 2002) proposed that it can measure three distinct aspects of attention: alerting, spatial orienting, plus executive control of response competition. We implemented the ANT in 50 healthy young adults, who also underwent a behavioural battery of visual working memory (WM) tests. These visual WM tests were all variations on recent paradigms, used here with the aim of measuring potential individual differences in visual WM capacity; WM precision; or WM distractor-filtering. Principal component analysis of the behavioural dataset revealed three main components. Interestingly, each component paired one aspect of ANT scores together with one aspect of WM scores, in terms of the strongest loadings. WM capacity loaded with ANT alerting; WM precision with ANT orienting; and WM filtering with ANT executive control. These results suggest that visual WM may involve separate component processes, and that different aspects of attention relate to different aspects of visual WM, in terms of behavioural individual differences. We discuss the observed pattern in relation to current issues and with respect to possible future work on the potential neural bases of individual differences in the distinct components.     

Deficit of endogenous spatial orienting of attention in children with benign epilepsy with centrotemporal spikes (BECTS)

Attention difficulties have been reported in children with benign epilepsy with centrotemporal spikes (BECTS) but have not yet been fully specified. The aim of this study was to evaluate the functions of exogenous and endogenous spatial orienting of attention and alerting in these children. Two versions of the spatial cueing paradigm and an alerting task, including trials with and without warning signal, were performed by 25 children with BECTS aged 6–12 years and 25 controls matched for age, gender and IQ. In these three tasks, patients were slower and made more omissions than controls. The alert effect amplitude was comparable in both groups at the longer SOAs (450 ms and 800 ms) while, at the shortest SOA (100 ms), it was greater in controls than in the BECTS group. In the first version of the spatial cueing task (peripheral cues and no probability information), the validity effect amplitude, measured by longer response times (RTs) in invalid trials compared to valid trials, was comparable in both groups. In the second version (central cues and a 75% probability that the target would appear at the cued location), the validity effect was larger in the BECTS group compared to controls because of a higher cost of invalid trials compared to neutral trials. These results suggest the existence of impairments in the endogenous orienting of attention in children with BECTS, in particular an attention disengagement deficit, while exogenous orienting of attention appears to be preserved.