Activity In Attention Networks Research Articles

Slow negative potentials in the pre-stimulus period in norm and patients with the first episode of schizophrenia

Behavioral data (correct response latency and errors number increase) indicate a significant decrease in the task performance efficiency in patients with the first episode of schizophrenia, compared to the norm. At the same time the SNP 1, 2, 3 amplitudes were found to enhance in the patients group, compared to the norm, which may reflect a compensatory activation of predictive attention and inhibition cortical networks for increase the response efficiency. Intergroup differences in the topography of the SNP1 and SNP2 peaks amplitude suggest “disorganization” of the left hemisphere cognitive control cortical networks at the early stage of schizophrenia. It is assumed that the SNP 1, 2, 3 components can be considered as potentially significant clinically markers of cognitive control disorders in schizophrenia.

Sleep Deprivation Effects on Brain State Dynamics Are Associated With Dopamine D2 Receptor Availability Via Network Control Theory

BackgroundSleep deprivation (SD) negatively affects brain function. Most brain imaging studies have investigated the effects of SD on static brain function. SD effects on functional brain dynamics and their relationship with molecular changes remain relatively unexplored. MethodsWe used functional magnetic resonance imaging to examine resting-brain state dynamics after one night of SD compared with rested wakefulness (N = 41) and assessed the association of brain state dynamics with striatal brain dopamine D2 receptor availability measured by positron emission tomography [11C]raclopride using network control theory. ResultsSD reduced dwell time and persistence probabilities, with the strongest effects in two brain states, one characterized by high default mode network and low dorsal attention network activity and the other by high frontoparietal network and low somatomotor network activity. Using network control theory, we showed that after SD, there was an overall increase in the control energy required for brain state transitions, with effects varying for different brain state transitions. Control energy requirement was negatively associated with transition probabilities under SD and restful wakefulness and accounted for SD-induced changes in transition probabilities. Alteration in the energy landscape was associated with SD-induced changes in striatal D2 receptor distribution. ConclusionsThese findings demonstrate altered occurrence of internally and externally oriented brain states following acute SD and suggest an association with energy requirements for brain state transitions modulated by striatal D2 receptors.

Neurophysiological markers in community-dwelling older adults with mild cognitive impairment: an EEG study

BackgroundNeurodegeneration and structural changes in the brain due to amyloid deposition have been observed even in individuals with mild cognitive impairment (MCI). EEG measurement is considered an effective tool because it is noninvasive, has few restrictions on the measurement environment, and is simple and easy to use. In this study, we investigated the neurophysiological characteristics of community-dwelling older adults with MCI using EEG.MethodsDemographic characteristics, cognitive function, physical function, resting-state MRI and electroencephalogram (rs-EEG), event-related potentials (ERPs) during Simon tasks, and task proportion of correct responses and reaction times (RTs) were obtained from 402 healthy controls (HC) and 47 MCI participants. We introduced exact low-resolution brain electromagnetic tomography-independent component analysis (eLORETA-ICA) to assess the rs-EEG network in community-dwelling older adults with MCI.ResultsA lower proportion of correct responses to the Simon task and slower RTs were observed in the MCI group (p < 0.01). Despite no difference in brain volume between the HC and MCI groups, significant decreases in dorsal attention network (DAN) activity (p < 0.05) and N2 amplitude of ERP (p < 0.001) were observed in the MCI group. Moreover, DAN activity demonstrated a correlation with education (Rs = 0.32, p = 0.027), global cognitive function (Rs = 0.32, p = 0.030), and processing speed (Rs = 0.37, p = 0.010) in the MCI group. The discrimination accuracy for MCI with the addition of the eLORETA-ICA network ranged from 0.7817 to 0.7929, and the area under the curve ranged from 0.8492 to 0.8495.ConclusionsThe eLORETA-ICA approach of rs-EEG using noninvasive and relatively inexpensive EEG demonstrates specific changes in elders with MCI. It may provide a simple and valid assessment method with few restrictions on the measurement environment and may be useful for early detection of MCI in community-dwelling older adults.

7. Amygdala, Central Executive, Ventral Attention, and Salience Network Connectivity and Activity During Emotion Processing Associated With Present and Future Mania and Depression Severity in Three Independent Young Adult Samples

7. Amygdala, Central Executive, Ventral Attention, and Salience Network Connectivity and Activity During Emotion Processing Associated With Present and Future Mania and Depression Severity in Three Independent Young Adult Samples

Dorsal attention network activity during perceptual organization is distinct in schizophrenia and predictive of cognitive disorganization.

Visual shape completion is a canonical perceptual organization process that integrates spatially distributed edge information into unified representations of objects. People with schizophrenia show difficulty in discriminating completed shapes, but the brain networks and functional connections underlying this perceptual difference remain poorly understood. Also unclear is whether brain network differences in schizophrenia occur in related illnesses or vary with illness features transdiagnostically. To address these topics, we scanned (functional magnetic resonance imaging, fMRI) people with schizophrenia, bipolar disorder, or no psychiatric illness during rest and during a task in which they discriminated configurations that formed or failed to form completed shapes (illusory and fragmented condition, respectively). Multivariate pattern differences were identified on the cortical surface using 360 predefined parcels and 12 functional networks composed of such parcels. Brain activity flow mapping was used to evaluate the likely involvement of resting-state connections for shape completion. Illusory/fragmented task activation differences ('modulations') in the dorsal attention network (DAN) could distinguish people with schizophrenia from the other groups (AUCs > .85) and could transdiagnostically predict cognitive disorganization severity. Activity flow over functional connections from the DAN could predict secondary visual network modulations in each group, except in schizophrenia. The secondary visual network was strongly and similarly modulated in each group. Task modulations were dispersed over more networks in patients compared to controls. In summary, DAN activity during visual perceptual organization is distinct in schizophrenia, symptomatically relevant, and potentially related to improper attention-related feedback into secondary visual areas.

A Multimodal Evaluation of Podcast Learning, Retention, and Electroencephalographically Measured Attention in Medical Trainees.

Podcasts have become popular among medical trainees. However, it is unclear how well learners retain information from podcasts compared to traditional educational modalities, and whether multitasking affects the learner's ability to pay attention and learn. This study attempted to examine the effectiveness of podcast learning by using electroencephalography (EEG) to measure learner attention, in addition to test performance, task load, and preferences. The study used a repeated measures design with three conditions: podcast listening on a treadmill, podcast listening seated, and textbook reading seated. Participants were anesthesiology residents and medical students at a large United States academic medical center. Three topics were chosen: allergic response, liver physiology, and statistics. Each participant studied all three topics that were randomly assigned to one of three learning conditions - in random order. Participants completed a knowledge test at baseline, after each condition, and at four-week follow-up, and reported preferred learning modality and task load under each modality. Activation levels in alerting, orienting, and executive attentional networks were examined using EEG. Results: Sixty-one participants (11 anesthesiology residents and 50 medical students) were included in the study. Of the 61, six were excluded from the EEG analyses due to corrupted recordings. EEG results showed that mean attention network activation scores did not differ between the study conditions. Trainees preferred podcast learning over reading for all three topics. When compared to textbook reading, podcast learning (seated or on a treadmill) produced significantly better learning gain, and equivalent retention for two of the three topics. Our study is the first to use neurocognitive data, self-reported satisfaction, and knowledge test performance to demonstrate that podcasts are at least equivalent to textbooks for maintaining attention, immediate learning, and retention - even while exercising.

Self-relevance and the activation of attentional networks.

Recent theoretical accounts maintain that core components of attentional functioning are preferentially tuned to self-relevant information. Evidence in support of this viewpoint is equivocal, however, with research overly reliant on personally significant (i.e., familiar) stimulus inputs (e.g., faces, forenames) and a diverse range of methodologies. Addressing these limitations, here we utilised arbitrary items (i.e., geometric shapes) and administered the Attention Network Test (ANT) to establish the extent to which self-relevance (vs friend-relevance) moderates the three subsystems of attentional functioning-alerting, orienting, and executive control. The results revealed that only executive control was sensitive to the meaning of the stimuli, such that conflict resolution was enhanced following the presentation of self-associated compared with friend-associated shapes (i.e., cues). Probing the origin of this effect, a further computational analysis (i.e., Shrinking Spotlight Diffusion Model analysis) indicated that self-relevance facilitated the narrowing of visual attention. These findings highlight when and how the personal significance of otherwise trivial material modulates attentional processing.

Catching wandering minds with tapping fingers: neural and behavioral insights into task-unrelated cognition.

When the human mind wanders, it engages in episodes during which attention is focused on self-generated thoughts rather than on external task demands. Although the sustained attention to response task is commonly used to examine relationships between mind wandering and executive functions, limited executive resources are required for optimal task performance. In the current study, we aimed to investigate the relationship between mind wandering and executive functions more closely by employing a recently developed finger-tapping task to monitor fluctuations in attention and executive control through task performance and periodical experience sampling during concurrent functional magnetic resonance imaging (fMRI) and pupillometry. Our results show that mind wandering was preceded by increases in finger-tapping variability, which was correlated with activity in dorsal and ventral attention networks. The entropy of random finger-tapping sequences was related to activity in frontoparietal regions associated with executive control, demonstrating the suitability of this paradigm for studying executive functioning. The neural correlates of behavioral performance, pupillary dynamics, and self-reported attentional state diverged, thus indicating a dissociation between direct and indirect markers of mind wandering. Together, the investigation of these relationships at both the behavioral and neural level provided novel insights into the identification of underlying mechanisms of mind wandering.

Longitudinal investigation of brain activation during motor tasks in Friedreich ataxia: 24-month data from IMAGE-FRDA.

Friedreich ataxia (FRDA) is a progressive autosomal recessive disease. While motor dysfunction is the primary neurological hallmark, little is known about the underlying neurobiological changes associated with motor deficits over the course of disease. We investigated the hypothesis that progressive functional changes in both the cerebellum and cerebrum are related to longitudinal changes in performance on complex motor tasks in individuals with FRDA. Twenty-two individuals with FRDA and 28 controls participated over 24months. The longitudinal investigation included finger tapping tasks with different levels of complexity (i.e., visually cued, multi-finger; self-paced, single finger), performed in conjunction with fMRI acquisitions, to interrogate changes in the neurobiology of motor and attentional brain networks including the cerebellum and cerebrum. We demonstrated evidence for significant longitudinal decreased cerebral fMRI activity over time in individuals with FRDA, relative to controls, during an attentionally-demanding motor task (visually cued tapping of multiple fingers) in six cerebral regions: right and left superior frontal gyri, right superior temporal gyrus, right primary somatosensory area, right anterior cingulate cortex, and right medial frontal gyrus. Importantly, longitudinal decreased activity was associated with more severe disease status at baseline, higher GAA1 repeat length and earlier age of onset. These findings suggest a dynamic pattern of neuronal activity in motor, attention and executive control networks over time in individuals with FRDA, which is associated with increased disease severity at baseline, increased GAA1 repeat length and earlier age at onset.

Dissociating the Neural Correlates of Consciousness and Task Relevance in Face Perception Using Simultaneous EEG-fMRI.

Current theories of visual consciousness disagree about whether it emerges during early stages of processing in sensory brain regions or later when a widespread frontoparietal network becomes involved. Moreover, disentangling conscious perception from task-related postperceptual processes (e.g., report) and integrating results across different neuroscientific methods remain ongoing challenges. The present study addressed these problems using simultaneous EEG-fMRI and a specific inattentional blindness paradigm with three physically identical phases in female and male human participants. In phase 1, participants performed a distractor task during which line drawings of faces and control stimuli were presented centrally. While some participants spontaneously noticed the faces in phase 1, others remained inattentionally blind. In phase 2, all participants were made aware of the task-irrelevant faces but continued the distractor task. In phase 3, the faces became task-relevant. Bayesian analysis of brain responses demonstrated that conscious face perception was most strongly associated with activation in fusiform gyrus (fMRI) as well as the N170 and visual awareness negativity (EEG). Smaller awareness effects were revealed in the occipital and prefrontal cortex (fMRI). Task-relevant face processing, on the other hand, led to strong, extensive activation of occipitotemporal, frontoparietal, and attentional networks (fMRI). In EEG, it enhanced early negativities and elicited a pronounced P3b component. Overall, we provide evidence that conscious visual perception is linked with early processing in stimulus-specific sensory brain areas but may additionally involve prefrontal cortex. In contrast, the strong activation of widespread brain networks and the P3b are more likely associated with task-related processes.SIGNIFICANCE STATEMENT How does our brain generate visual consciousness-the subjective experience of what it is like to see, for example, a face? To date, it is hotly debated whether it emerges early in sensory brain regions or later when a widespread frontoparietal network is activated. Here, we use simultaneous fMRI and EEG for high spatial and temporal resolution and demonstrate that conscious face perception is predominantly linked to early and occipitotemporal processes, but also prefrontal activity. Task-related processes (e.g., decision-making), on the other hand, elicit brain-wide activations including late and strong frontoparietal activity. These findings challenge numerous previous studies and highlight the importance of investigating the neural correlates of consciousness in the absence of task relevance.

Neurobiology of loneliness: a systematic review.

Loneliness is associated with increased morbidity and mortality. Deeper understanding of neurobiological mechanisms underlying loneliness is needed to identify potential intervention targets. We did not find any systematic review of neurobiology of loneliness. Using MEDLINE and PsycINFO online databases, we conducted a search for peer-reviewed publications examining loneliness and neurobiology. We identified 41 studies (n = 16,771 participants) that had employed various methods including computer tomography (CT), structural magnetic resonance imaging (MRI), functional MRI (fMRI), electroencephalography (EEG), diffusion tensor imaging (DTI), single-photon emission computed tomography (SPECT), positron emission tomography (PET), and post-mortem brain tissue RNA analysis or pathological analysis. Our synthesis of the published findings shows abnormal structure (gray matter volume or white matter integrity) and/or activity (response to pleasant versus stressful images in social versus nonsocial contexts) in the prefrontal cortex (especially medial and dorsolateral), insula (particularly anterior), amygdala, hippocampus, and posterior superior temporal cortex. The findings related to ventral striatum and cerebellum were mixed. fMRI studies reported links between loneliness and differential activation of attentional networks, visual networks, and default mode network. Loneliness was also related to biological markers associated with Alzheimer’s disease (e.g., amyloid and tau burden). Although the published investigations have limitations, this review suggests relationships of loneliness with altered structure and function in specific brain regions and networks. We found a notable overlap in the regions involved in loneliness and compassion, the two personality traits that are inversely correlated in previous studies. We have offered recommendations for future research studies of neurobiology of loneliness.

Altered Visual Attention and Default Mode Network Activity in Adults With Major Depressive Disorder

Neurophysiologic anomalies in major depressive disorder (MDD) have been characterized using electroencephalography (EEG) and functional imaging. In healthy persons, occipital alpha oscillations are thought to indicate top-down inhibition of the visual system, particularly visual attention. Different patterns of occipital alpha or altered relationships of alpha to relevant network activity could reflect connectivity deficits that impact visual processing and attention in MDD.

Abnormal dorsal attention network activation in memory impairment after traumatic brain injury.

Memory impairment is a common, disabling effect of traumatic brain injury. In healthy individuals, successful memory encoding is associated with activation of the dorsal attention network as well as suppression of the default mode network. Here, in traumatic brain injury patients we examined whether: (i) impairments in memory encoding are associated with abnormal brain activation in these networks; (ii) whether changes in this brain activity predict subsequent memory retrieval; and (iii) whether abnormal white matter integrity underpinning functional networks is associated with impaired subsequent memory. Thirty-five patients with moderate-severe traumatic brain injury aged 23-65 years (74% males) in the post-acute/chronic phase after injury and 16 healthy control subjects underwent functional MRI during performance of an abstract image memory encoding task. Diffusion tensor imaging was used to assess structural abnormalities across patient groups compared to 28 age-matched healthy controls. Successful memory encoding across all participants was associated with activation of the dorsal attention network, the ventral visual stream and medial temporal lobes. Decreased activation was seen in the default mode network. Patients with preserved episodic memory demonstrated increased activation in areas of the dorsal attention network. Patients with impaired memory showed increased left anterior prefrontal activity. White matter microstructure underpinning connectivity between core nodes of the encoding networks was significantly reduced in patients with memory impairment. Our results show for the first time that patients with impaired episodic memory show abnormal activation of key nodes within the dorsal attention network and regions regulating default mode network activity during encoding. Successful encoding was associated with an opposite direction of signal change between patients with and without memory impairment, suggesting that memory encoding mechanisms could be fundamentally altered in this population. We demonstrate a clear relationship between functional networks activated during encoding and underlying abnormalities within the structural connectome in patients with memory impairment. We suggest that encoding failures in this group are likely due to failed control of goal-directed attentional resources.

Neurophysiological evidence of impaired attention and working memory in untreated hematologic cancer patients

ObjectiveNeuroimaging studies of hematologic cancer patients report altered activity in dorsal attention and central executive networks. To determine the consequences of these altered brain networks, we evaluated neurophysiological correlates of attention and working memory in hematologic cancer patients prior to initiating treatment. MethodsHematologic cancer patients (19–80 years) were excluded for premorbid cognitive impairment, prior non-hematologic cancer diagnosis, and prior chemotherapy. Attention was manipulated by presenting an irrelevant spatial cue prior to visual search displays. Working memory was manipulated by presenting irrelevant distractors within memory displays. Electroencephalogram was recorded during task performance. ResultsPatients (n = 28) and controls (n = 15) were balanced on age, gender, and education. Spatial cues evoked larger N2pc amplitudes, a correlate of spatial attention, in patients than controls (p < .05; Cohen’s d > 0.7). Memory distractors evoked larger contralateral delay activity amplitudes, a correlate of working memory load, in patients (p = .028; Cohen’s d = 1.1) but not controls (p = .64). ConclusionsPrior to initiating treatment, hematologic cancer patients demonstrated poor control over spatial attention and working memory, consistent with altered dorsal attention and central executive network activity. SignificanceHematologic cancer patients may be at a higher risk for selecting, processing, and storing distracting information that would compete with more immediate goal-related behaviors.

Predicting an individual's dorsal attention network activity from functional connectivity fingerprints.

The cortical dorsal attention network (DAN) is a set of parietal and frontal regions that support a wide variety of attentionally demanding tasks. Whereas attentional deployment reliably drives DAN activity across subjects, there is a large degree of variation in the activation pattern in individual subjects. We hypothesize that a subject's own idiosyncratic pattern of cortical DAN activity can be predicted from that subject's own unique pattern of functional connectivity. By modeling task activation as a function of whole brain connectivity patterns, we are able to define the connectivity fingerprints for the frontal and parietal DAN, and use it to predict a subject's characteristic DAN activation pattern with high accuracy. These predictions outperform the standard group-average benchmark and predict a subject's own activation pattern above and beyond predictions from another subject's connectivity pattern. Thus an individual's distinctive connectivity pattern accounts for substantial variance in DAN functional responses. Last, we show that the set of connections that predict cortical DAN responses, the frontal and parietal DAN connectivity fingerprints, is predominantly composed of other coactive regions, including regions outside of the DAN including occipital and temporal visual cortices. These connectivity fingerprints represent defining computational characteristics of the DAN, delineating which voxels are or are not capable of exerting top-down attentional bias to other regions of the brain. NEW & NOTEWORTHY The dorsal attention network (DAN) is a set of regions in frontoparietal cortex that reliably activate during attentional tasks. We designed computational models that predict the degree of an individual's DAN activation using their resting-state connectivity pattern alone. This uncovered the connectivity fingerprints of the DAN, which define it so well that we can predict how a voxel will respond to an attentional task given only its pattern of connectivity, with outstanding accuracy.

Age- and Expertise-Related Differences of Sensorimotor Network Dynamics during Force Control

Age-related deterioration of force control is evident on behavioral and neural levels. Extensive and deliberate practice can decrease these changes. This study focused on detecting electrophysiological correlates of age- and expertise-related differences in force control. We examined young (20–27 years) and late middle-aged (57–67 years) novices as well as late middle-aged experts in the field of fine motor control. Therefore, EEG data were recorded while participants performed a force maintenance task. Variability and complexity of force data were analyzed. To detect electrophysiological correlates, dynamic mode decomposition (DMD) was applied to EEG data. DMD allows assessing brain network dynamics by extracting electrode interrelations and their dynamics. Defining clusters of electrodes, we focused on sensorimotor and attentional networks. We confirmed that force control in late middle-aged novices was more variable and less complex than in other groups. Analysis of task-related overall network characteristics, showed a decrease within the α band and increase within low β, high β, and θ band. Compared to the other groups young novices presented a decreased α magnitude. High β magnitude was lower in late middle-aged novices than for other groups. Comparing left and right hands’ performance, young novices showed higher low β magnitude for the left hand. Late middle-aged novices showed high values for both hands while late middle-aged experts showed higher values for the right than for their left hand. Activation of attentional networks was lower in late middle-aged experts compared to novices. These results may relate to different control strategies of the three groups.

Altered Neural Dynamics during a Flanker Attention Task in Patients with Type 1 Diabetes

Background: Patients with type 1 diabetes appear to have deficits in specific cognitive domains, particularly in attention and executive function (1). In this study, we used magnetoencephalography (MEG; 2), a noninvasive functional neuroimaging method, to identify neuronal changes in attention processing in otherwise healthy young adults with type 1 diabetes during euglycemia. Methods: Adults with type 1 diabetes and no micro- or macro-vascular complications (N = 38) completed a visual selective attention task during MEG. A demographically-matched control group without type 1 diabetes was used for comparison. Each trial began with a fixation cross presented centrally, followed by a row of 5 arrows. Participants were asked to respond regarding the direction of the middle arrow (right index finger for left, right middle finger for right) and ignore the flanking arrows that were presented in either the same (congruent condition) or opposite direction (incongruent condition). All MEG data was processed following standard protocols (3), and the resulting images of functional brain activity were examined statistically. Results: While no differences in reaction time or accuracy were found between groups, patients recruited a more widespread network of task relevant brain regions compared to controls, particularly the prefrontal cortex and anterior cingulate. Patients had a greater alpha increase from baseline in the anterior cingulate (p &amp;lt; .01), an important brain region in attention, and in the prefrontal cortex (p &amp;lt; .01) as compared to controls, likely reflecting compensatory mechanisms at play. Conclusions: These results indicate that type 1 diabetes affects neural activity in attention networks of patients who are otherwise healthy and without major comorbidities, reflecting the recruitment of compensatory neural responses to complete task goals. Disclosure C.M. Embury: None. T.J. McDermott: None. A.I. Wiesman: None. K. Brau: None. C. Desouza: Consultant; Self; Novo Nordisk A/S, Sanofi. Research Support; Self; Merck &amp; Co., Inc.. Advisory Panel; Self; Medscape. A. Drincic: None. T.W. Wilson: None.

Differences in Hearing Acuity among "Normal-Hearing" Young Adults Modulate the Neural Basis for Speech Comprehension.

In this paper, we investigate how subtle differences in hearing acuity affect the neural systems supporting speech processing in young adults. Auditory sentence comprehension requires perceiving a complex acoustic signal and performing linguistic operations to extract the correct meaning. We used functional MRI to monitor human brain activity while adults aged 18–41 years listened to spoken sentences. The sentences varied in their level of syntactic processing demands, containing either a subject-relative or object-relative center-embedded clause. All participants self-reported normal hearing, confirmed by audiometric testing, with some variation within a clinically normal range. We found that participants showed activity related to sentence processing in a left-lateralized frontotemporal network. Although accuracy was generally high, participants still made some errors, which were associated with increased activity in bilateral cingulo-opercular and frontoparietal attention networks. A whole-brain regression analysis revealed that activity in a right anterior middle frontal gyrus (aMFG) component of the frontoparietal attention network was related to individual differences in hearing acuity, such that listeners with poorer hearing showed greater recruitment of this region when successfully understanding a sentence. The activity in right aMFGs for listeners with poor hearing did not differ as a function of sentence type, suggesting a general mechanism that is independent of linguistic processing demands. Our results suggest that even modest variations in hearing ability impact the systems supporting auditory speech comprehension, and that auditory sentence comprehension entails the coordination of a left perisylvian network that is sensitive to linguistic variation with an executive attention network that responds to acoustic challenge.

A typical social attention behaviors and its underlying neural mechanism in individuals with autism spectrum disorder

The ability to coordinate attention to events or objects between interactive social partners, referred to as social attention, is of great significance for adaptive social behaviors and nonverbal communications in our daily life, helping us to infer other person’s inner state (e.g., intentions, goals) and learn about where important events (e.g., food, danger) occur in the environment. In recent years, many studies have demonstrated that social cues (e.g., eye gaze, head orientation and walking direction of biological motion) can trigger reflexive attentional orienting effects using adapted central cueing paradigm originally designed by Posner. However, not all of us are equally adept at directing attention to where others are focusing on, and this ability is strongly impaired in individuals with autism spectrum disorder (ASD), a highly genetic neurodevelopmental disorder marked by striking social deficits and repetitive behaviors. Here we systematically reviewed recent work on abnormal social attention behaviors and its underlying neural mechanisms in ASD. We first expatiated a typical social attention behaviors indexed by covert and overt attention in ASD. It has been documented that ASD individuals tend to show reduced reflexive orienting effect manifesting itself in both covert attention and overt eye movement compared to typically developing individuals (TD). Yet some controversies concerning the malfunction of social attention in ASD remain to be resolved, based on some evidence demonstrating comparable orienting effect between ASD and TD group. Then we summarized the development course of social attention in ASD. Crucially, atypical orienting to eye gaze is more likely to be observed in younger children but not older children or adults with ASD. It is reasonable to postulate that ASD individuals may acquire this ability through overlearning the association between social cues and targets in everyday life as they grow older. Furthermore, we discussed the neural basis of abnormal social attention behaviors in ASD. Using a combination of psychophysical paradigms and neuroimaging techniques, researchers have reported atypical neural activities in superior temporal gyrus and prefrontal cortex under the supraliminal condition as well as abnormal activation in amygdala under the subliminal condition in the brain of ASD. Moreover, the ASD group showed much less difference in activation of frontoparietal attention networks between social and nonsocial attention task than the TD group, implying disruptive social attention in ASD. Finally, several perspectives on further investigations were put forward given the controversies and insufficient evidence concerning the malfunction of social attention in ASD. Future studies should employ multiple types of social cues (e.g., eye gaze and walking direction of biological motion) in conjunction with more ecological paradigms to investigate conscious and non-conscious social attention behaviors from a developmental approach. More importantly, more neuroimaging studies are needed to explore the functional connections among several key cortical regions and subcortical regions underlying atypical social attention behaviors in ASD. Such efforts will help to facilitate the early diagnosis and intervention of ASD.

Modafinil enhances alerting-related brain activity in attention networks.

Modafinil is a wake-promoting agent and has been reported to be effective in improving attention in patients with attentional disturbance. However, neural substrates underlying the modafinil effects on attention are not fully understood. We employed a functional magnetic resonance imaging (fMRI) study with the attention network test (ANT) task in healthy adults and examined which networks of attention are mainly affected by modafinil and which neural substrates are responsible for the drug effects. We used a randomized placebo-controlled within-subjects cross-over design. Twenty-three healthy adults participated in two series of an fMRI study, taking either a placebo or modafinil. The participants performed the ANT task, which is designed to measure three distinct attentional networks, alerting, orienting, and executive control, during the fMRI scanning. The effects of modafinil on behavioral performance and regional brain activity were analyzed. We found that modafinil enhanced alerting performance and showed greater alerting network activity in the left middle and inferior occipital gyri as compared with the placebo. The brain activations in the occipital regions were positively correlated with alerting performance. Modafinil enhanced alerting performance and increased activation in the occipital lobe in the alerting network possibly relevant to noradrenergic activity during the ANT task. The present study may provide a rationale for the treatment of patients with distinct symptoms of impaired attention.