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This study addresses an issue in attentional distribution in a binocular visual system using RSVP tasks under Attentional Blink (AB) experimental protocols. In Experiment 1, we employed dichoptic RSVP to verify whether, under interocular competition, attention may be captured by a monocular channel. Experiment 2 was a control experiment, where a monoptic RSVP assessed by both or only one eye determines whether Experiment 1 monocular condition results were due to an allocation of attention to one eye. Experiment 3 was also a control experiment designed to determine whether Experiment 1 results were due to the effect of interocular competition or to a diminished visual contrast. Results from Experiment 1 revealed that dichoptic presentations caused a delay in the type stage of the Wyble's eSTST model, postponing the subsequent tokenization process. The delay in monocular conditions may be further explained by a visual attenuation, due to fusion of target and an empty frame. Experiment 2 evidenced the attentional allocation to monocular channels when forced by eye occlusion. Experiment 3 disclosed that monocular performance in Experiment 1 differs significantly from conditions with interocular competition. While both experiments revealed similar performance in monocular conditions, rivalry conditions exhibit lower detection rates, suggesting that competing stimuli was not responsible for Experiment 1 results. These findings highlight the differences between dichoptic and monoptic presentations of stimuli, particularly on the AB effect, which appears attenuated or absent in dichoptic settings. Furthermore, results suggest that monoptic presentation and binocular fusion stages were a necessary condition for the attentional allocation. [ABSTRACT FROM AUTHOR]

Background: Covert visuo-spatial attention is marked by the anticipatory lateralization of neuronal alpha activity in the posterior parietal cortex. Previous applications of transcranial alternating current stimulation (tACS) at the alpha frequency, however, were inconclusive regarding the causal contribution of oscillatory activity during visuo-spatial attention. Objective: Attentional shifts of behavior and electroencephalography (EEG) after-effects were assessed in a cued visuo-spatial attention paradigm. We hypothesized that parietal alpha-tACS shifts attention relative to the ipsilateral visual hemifield. Furthermore, we assumed that modulations of behavior and neurophysiology are related to individual electric field simulations. Methods: We applied personalized tACS at alpha and gamma frequencies to elucidate the role of oscillatory neuronal activity for visuo-spatial attention. Personalized tACS montages were algorithmically optimized to target individual left and right parietal regions that were defined by an EEG localizer. Results: Behavioral performance in the left hemifield was specifically increased by alpha-tACS compared to gamma-tACS targeting the left parietal cortex. This hemisphere-specific effect was observed despite the symmetry of simulated electric fields. In addition, visual event-related potential (ERP) amplitudes showed a reduced lateralization over posterior sites induced by left alpha-tACS. Neuronal sources of this effect were localized in the left premotor cortex. Interestingly, accuracy modulations induced by left parietal alpha-tACS were directly related to electric field magnitudes in the left premotor cortex. Conclusion: Overall, results corroborate the notion that alpha lateralization plays a causal role in covert visuo-spatial attention and indicate an increased susceptibility of parietal and premotor brain regions of the left dorsal attention network to subtle tACS-neuromodulation.

Although the link between developmental dyslexia and visual-spatial deficit has been recurrently highlighted, the relationship between visual-spatial abilities and reading performance is still a controversial issue, considering the orthographic variability of the language being learned. This study aimed to examine whether visuo-spatial abilities (i.e. attention, short-term memory, and relations) contribute significantly to predicting word and pseudo-word reading independently of phonological awareness in Arabic speaking children in grades 4 and 5. An inter-groups comparison between two groups of readers comprising typical readers (n = 44) and children with dyslexia (n = 32). All participants were tested in phonological (phonological awareness) and visuo-spatial measures (visual short-term memory test, visuo-spatial attention, and visuo-spatial relations). Results showed that typical readers outperformed the group of dyslexics in all the phonological and visuo-spatial measures. Visuo-spatial abilities were also a contributing factor in predicting word reading after controlling for phonological awareness, age, and non-verbal reasoning. Findings indicate that vowelised word reading in Arabic is heavily underpinned by phonological awareness and visuo-spatial abilities, found to be impaired in a group with dyslexia. Findings are viewed in the frame that reveals the integrated roles of phonological awareness and visual and spatial abilities in reading development. [ABSTRACT FROM AUTHOR]

Covert visuo-spatial attention is marked by the anticipatory lateralization of neuronal alpha activity in the posterior parietal cortex. Previous applications of transcranial alternating current stimulation (tACS) at the alpha frequency, however, were inconclusive regarding the causal contribution of oscillatory activity during visuo-spatial attention. Attentional shifts of behavior and electroencephalography (EEG) after-effects were assessed in a cued visuo-spatial attention paradigm. We hypothesized that parietal alpha-tACS shifts attention relative to the ipsilateral visual hemifield. Furthermore, we assumed that modulations of behavior and neurophysiology are related to individual electric field simulations. We applied personalized tACS at alpha and gamma frequencies to elucidate the role of oscillatory neuronal activity for visuo-spatial attention. Personalized tACS montages were algorithmically optimized to target individual left and right parietal regions that were defined by an EEG localizer. Behavioral performance in the left hemifield was specifically increased by alpha-tACS compared to gamma-tACS targeting the left parietal cortex. This hemisphere-specific effect was observed despite the symmetry of simulated electric fields. In addition, visual event-related potential (ERP) amplitudes showed a reduced lateralization over posterior sites induced by left alpha-tACS. Neuronal sources of this effect were localized in the left premotor cortex. Interestingly, accuracy modulations induced by left parietal alpha-tACS were directly related to electric field magnitudes in the left premotor cortex. Overall, results corroborate the notion that alpha lateralization plays a causal role in covert visuo-spatial attention and indicate an increased susceptibility of parietal and premotor brain regions of the left dorsal attention network to subtle tACS-neuromodulation. • Left parietal alpha-versus gamma-tACS biases attention towards the left hemifield. • Symmetric personalized E-fields indicate a functional asymmetry of attention modulation. • The left dorsal attention network is more susceptible to alpha-tACS neuromodulation. • Reduced ERP lateralization during left alpha-tACS projects to left premotor sources. • Electric fields in left premotor cortex correlate with behavioral attention shift. [ABSTRACT FROM AUTHOR]

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The N2pc event‐related potential is a widely studied ERP component that reflects the covert deployment of visuo‐spatial attention to target stimuli displayed laterally relative to fixation. Recently, an analogous ERP component, named N2pcb, has been proposed as a marker of the deployment of visuo‐spatial attention to targets displayed on the vertical midline. Two studies that investigated the N2pcb component found analogous results, using however two different algorithms to compute the amplitude of N2pcb. One study subtracted the ipsilateral activity elicited by a lateral target from the bilateral activity elicited by a target displayed on the vertical midline, whereas the other study subtracted the bilateral activity elicited by target‐absent displays from the bilateral activity elicited by a target displayed on the vertical midline. Here we show both algorithms estimate properly the N2pc as well as the N2pcb components. In addition, we explored whether the singleton detection positivity (SDP) component, a posterior bilateral positivity temporally concomitant to N2pc recently reported in studies using singleton search, could be observed in the present study in which a target was defined by a combination of features. Given that such component was indeed found using feature search, we named this component posterior processing positivity (PPP), and showed that bilateral activity elicited by target‐absent displays is an adequate baseline for its correct isolation. Here we describe a valid alternative to the prototypical contralateral‐minus‐ipsilateral ERP subtraction for the isolation of N2pc, an established ERP hallmark of attention allocation to laterally displayed task‐relevant information. Unilateral N2pc, bilateral N2pcb, and a new component reflecting high‐level processing of task‐relevant information, named posterior processing positivity (PPP), can all be isolated in visual search by using bilateral ERPs elicited by target‐absent search arrays as a common baseline. [ABSTRACT FROM AUTHOR]

In the adult brain, biases in the allocation of spatial attention can be measured using a line bisection task and are directly relatable to neural attention signals in the fronto‐parietal attention network. Behavioral studies on the development of spatial biases have yielded a host of inconsistent results, likely due to variance in sample size, definition of experimental groups, and motor confounds introduced by using a paper‐and‐pencil version of a line bisection task. Here, we used a perceptual, computerized version of this task and examined the development of spatial biases in 459 children from grades 1–8 and 61 college freshmen. We found that children in early elementary grades exerted a significant leftward bias that gradually diminished with advancing grade level. We further show that among children in early elementary school grades, the degree of leftward spatial bias predicted better performance on a rapid automatized naming test, a predictor of reading ability. Significant leftward biases in early elementary school grades may be due to reading experience, thereby reflecting an interaction of the attention network with the evolving reading network. [ABSTRACT FROM AUTHOR]

Numerous studies have shown a consistent relationship between verbal working memory (WM) and native-language as well as non-native language learning abilities. However, the role of attentional abilities has been rarely explored, although these abilities have been shown to be associated both with verbal working memory and oral language proficiency. This study investigated the association between WM, attention and language proficiency in young adults raised with three different languages (Luxembourgish, German and French). Auditory-verbal WM abilities were assessed via an immediate serial recall task. Attentional abilities were assessed via auditory-verbal and visuo-spatial attentional tasks. Using a Bayesian correlational approach, we observed robust evidence for an association between auditory-verbal WM abilities and non-native language proficiency. At the same time, we observed no reliable evidence in favor of an association between language proficiency and auditory-verbal/visuo-spatial attentional measures. These results suggest that auditory-verbal WM and non-native language proficiency are strongly linked in young multilingual adults, irrespective of auditory-verbal or visuo-spatial attentional abilities.

Numerous studies have shown a consistent relationship between verbal working memory (WM) and native-language as well as non-native language learning abilities. However, the role of attentional abilities has been rarely explored, although these abilities have been shown to be associated both with verbal working memory and oral language proficiency. This study investigated the association between WM, attention and language proficiency in young adults raised with three different languages (Luxembourgish, German and French). Auditory-verbal WM abilities were assessed via an immediate serial recall task. Attentional abilities were assessed via auditory-verbal and visuo-spatial attentional tasks. Using a Bayesian correlational approach, we observed robust evidence for an association between auditory-verbal WM abilities and non-native language proficiency. At the same time, we observed no reliable evidence in favor of an association between language proficiency and auditory-verbal/visuo-spatial attentional measures. These results suggest that auditory-verbal WM and non-native language proficiency are strongly linked in young multilingual adults, irrespective of auditory- verbal or visuo-spatial attentional abilities. [ABSTRACT FROM AUTHOR]

Considering recent findings that breathing influences cognitive processes, two experiments explored the relationship between breathing and visuo-spatial attention. In Experiment 1, a lateralized probe detection task was inserted into the breathing cycles of 21 healthy adults to probe effects of breathing on the distribution of spatial attention. In Experiment 2 (N = 26), the Posner cueing task measured breathing-contingent detection speed for lateralized probes after endogenous or exogenous cueing. We consistently found faster responses for left probes after exhalation and for right probes after inhalation in both experiments. Breathing also affected the speed of re-alignment of spatial attention after invalid cueing in Experiment 2. This novel breathing bias shows that our ability to encode visuo-spatial information systematically fluctuates during breathing. [ABSTRACT FROM AUTHOR]

In a multi- and inter-cultural world, we daily encounter new words. Adult learners often rely on a situational context to learn and understand a new word's meaning. Here, we explored whether interactive learning facilitates word learning by directing the learner's attention to a correct new word referent when a situational context is non-informative. We predicted larger involvement of inferior parietal, frontal, and visual cortices involved in visuo-spatial attention during interactive learning. We scanned participants while they played a visual word learning game with and without a social partner. As hypothesized, interactive learning enhanced activity in the right Supramarginal Gyrus when the situational context provided little information. Activity in the right Inferior Frontal Gyrus during interactive learning correlated with post-scanning behavioral test scores, while these scores correlated with activity in the Fusiform Gyrus in the non-interactive group. These results indicate that attention is involved in interactive learning when the situational context is minimal and suggest that individual learning processes may be largely different from interactive ones. As such, they challenge the ecological validity of what we know about individual learning and advocate the exploration of interactive learning in naturalistic settings. [ABSTRACT FROM AUTHOR]

Abstract The role of norepinephrine (NE) in visuo-spatial attention remains poorly understood. Our goal was to identify the attentional processes influenced by atomoxetine (ATX) injections, a NE-reuptake inhibitor that boosts the level of NE in the brain, and to characterize these influences. We tested the effects of ATX injections, on seven monkeys performing a saccadic cued task in which cues and distractors were used to manipulate spatial attention. We found that when the cue accurately predicted the location of the upcoming cue in 80% of the trials, ATX consistently improved attentional orienting, as measured from reaction times (RTs). These effects were best accounted for by a faster accumulation rate in the valid trials, rather than by a change in the decision threshold. By contrast, the effect of ATX on alerting and distractor interference was more inconsistent. Finally, we also found that, under ATX, RTs to non-cued targets were longer when these were presented separately from cued targets. This suggests that the impact of NE on visuo-spatial attention depends on the context, such that the adaptive changes elicited by the highly informative value of the cues in the most frequent trials were accompanied by a cost in the less frequent trials. Highlights • Atomoxetine decreases reaction time of the most prevalent trials. • Atomoxetine modulates the accumulation rate of sensory information. • Atomoxetine adapts the response strategy to the context. [ABSTRACT FROM AUTHOR]

Abstract The occipital lobe contains a substantial part of the neural machinery involved in visual perception. Mutations in the LAMC3 gene have recently been shown to cause complex bilateral occipital cortical gyration abnormalities. However, to what extent these structural changes impact visual behavior is not known. We recorded responses for two screening test batteries targeting visual function (Leuven - Perceptual Organization Screening Test, Cortical Vision Screening Test) and measured eye fixation performance in a visual attention experiment from a patient with homozygous LAMC3 gene mutation. Using voxel-based morphometry (VBM) we quantitatively assessed the extent of structural changes brought on by the genetic mutation by comparing mean cortical curvature, cortical thickness, and gray matter volume in 34 cortical areas between patient and an age-, sex-, and education-matched control group. Anatomical connectivity between these cortical areas was investigated by a structural covariance analysis. Visual screening-, and behavioral results revealed that the patient's impairments were predominantly in visuo-spatial attention. Consistent with this, VBM and structural connectivity results revealed significant structural changes in cortical regions subserving attentional functions. We conclude that the LAMC3 gene mutation affects cortical areas beyond the occipital lobe and primarily those visual functions that involve heavily distributed networks – such as visuo-spatial attention. Highlights • LAMC3 gene mutation links to cortical structural changes beyond the occipital lobe. • LAMC3 gene mutation links to deficits in visual attention. • Structural changes primarily in cortical areas subserving visual attention. • Spared object and face recognition despite compromised cortical architecture. [ABSTRACT FROM AUTHOR]

Our ability to select relevant information from the environment is limited by the resolution of attention – i.e., the minimum size of the region that can be selected. Neural mechanisms that underlie this limit and its development are not yet understood. Functional magnetic resonance imaging (fMRI) was performed during an object tracking task in 7- and 11-year-old children, and in young adults. Object tracking activated canonical fronto-parietal attention systems and motion-sensitive area MT in children as young as 7 years. Object tracking performance improved with age, together with stronger recruitment of parietal attention areas and a shift from low-level to higher-level visual areas. Increasing the required resolution of spatial attention – which was implemented by varying the distance between target and distractors in the object tracking task – led to activation increases in fronto-insular cortex, medial frontal cortex including anterior cingulate cortex (ACC) and supplementary motor area, superior colliculi, and thalamus. This core circuitry for attentional precision was recruited by all age groups, but ACC showed an age-related activation reduction. Our results suggest that age-related improvements in selective visual attention and in the resolution of attention are characterized by an increased use of more functionally specialized brain regions during the course of development.

Objectives Visual attention is essential in sport performance, especially in fast paced team sports. Different game situations demand simultaneous attention to multiple, spatially separated objects/processes. But up till now, there is still a lack of appropriate training programs to optimize the athletes’ attention-window . Design and method Two intervention studies were implemented to examine the change of the attention-window's size of semi-professional team athletes and individual athletes through training in the lab (Study 1) and field (Study 2). Results The results of both studies demonstrate a positive effect of computer-based cognitive training in the lab and team training in the field on the expansion of athletes’ attention-window. Athletes showed an equal improvement of attentional performance caused by training in the lab and field. Conclusions The findings provide important insights for training measures/programs and basic knowledge on general cognition and attentional research. [ABSTRACT FROM AUTHOR]

Our ability to select relevant information from the environment is limited by the resolution of attention – i.e., the minimum size of the region that can be selected. Neural mechanisms that underlie this limit and its development are not yet understood. Functional magnetic resonance imaging (fMRI) was performed during an object tracking task in 7- and 11-year-old children, and in young adults. Object tracking activated canonical fronto-parietal attention systems and motion-sensitive area MT in children as young as 7 years. Object tracking performance improved with age, together with stronger recruitment of parietal attention areas and a shift from low-level to higher-level visual areas. Increasing the required resolution of spatial attention – which was implemented by varying the distance between target and distractors in the object tracking task – led to activation increases in fronto-insular cortex, medial frontal cortex including anterior cingulate cortex (ACC) and supplementary motor area, superior colliculi, and thalamus. This core circuitry for attentional precision was recruited by all age groups, but ACC showed an age-related activation reduction. Our results suggest that age-related improvements in selective visual attention and in the resolution of attention are characterized by an increased use of more functionally specialized brain regions during the course of development. [ABSTRACT FROM AUTHOR]

Anatomical studies conducted in neurological conditions have developed our understanding of the causal relationships between brain lesions and their clinical consequences. The analysis of lesion patterns extended across brain networks has been particularly useful in offering new insights on brain-behavior relationships. Here we applied multiperturbation Shapley value Analysis (MSA), a multivariate method based on coalitional game theory inferring causal regional contributions to specific behavioral outcomes from the characteristic functional deficits after stroke lesions. We established the causal patterns of contributions and interactions of nodes of the attentional orienting network onthe basis of lesion and behavioral data from 25 right hemisphere stroke patients tested in visuo-spatial attention tasks. We calculated the percentage of damaged voxels for five right hemisphere cortical regions contributing to attentional orienting, involving seven specific Brodmann Areas (BA): Frontal Eye Fields, (FEF-BA6), Intraparietal Sulcus (IPS-BA7), Inferior Frontal Gyrus (IFG-BA44/BA45), Temporo-Parietal Junction (TPJ-BA39/BA40), and Inferior Occipital Gyrus (IOG-BA19). We computed the MSA contributions of these seven BAs to three behavioral clinical tests (line bisection, bells cancellation, and letter cancelation). Our analyses indicated IPS as the main contributor to the attentional orienting and also revealed synergistic influences among IPS, TPJ and IOG (for bells cancellation and line bisection) and between TPJ and IFG (for bells and letter cancellation tasks). The findings demonstrate the ability of the MSA approach to infer plausible causal contributions of relevant right hemisphere sites in poststroke visuo-spatial attention and awareness disorders. [ABSTRACT FROM AUTHOR]

The ability to play action videogames – not directly related to phonological or orthographic training – seems to be a teaching tool able to intervene specifically on spatial attention and drastically improve the reading skills of dyslexic children. The MADRIGALE project aims at the design and development of an action game, simultaneously involving both phonological and attention training in order to adapt educational game strategies for special needs.

Time-of-day variation of visuo-spatial attention in relation to body temperature and subjective arousal was assessed. At five different times of day, alertness, covert, and overt orienting of attention were assessed in fifteen healthy subjects. Based on previous studies reporting a tight coupling of alerting and orienting the present study investigates potential attentional asymmetries induced by diurnal variations of arousal. Both covert and overt orienting of attention improved in the course of the day. However, no asymmetries between left and right visual hemifields could be detected. Covert orienting additionally covaried with body temperature, indicating a quite close relation between the attentional arousal and orienting system. Conversely, overt orienting only improved due to repeated testing but did not correlate with body temperature suggesting a partial independence of both modes of attentional orienting. It can be assumed that due to limited diurnal variations of arousal in the participants and practice effects caused by repeated testing, no attentional asymmetries could be provoked. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of the present study was comparing visuo-spatial attention between children with Attention Deficit Hyperactivity Disorder-Inattentive (ADHD-I) type and normal children. Methods: In this cross-sectional study fifteen (7-10 years of age) children were classified with ADHD-I type and 15 normal children were matched for age, sex, and IQ. They were selected trough simple random sampling. Measurement tools were Wechsler Intelligence Scale for children 4th edition (WISC-IV), the Edinburgh Handedness Inventory and the Star Cancellation Test. Results: The results suggest that there is no significant difference between ADHD-I and normal children from the visuo-spatial standpoint (P>0.05). But three ADHD-I children exhibited signs of unilateral neglect. Discussion: Although, in this study the visuo-spatial attention was not different between ADHD-I group and normal group, considering this form of attention as an item in assessment and therapeutic interventions should not be neglected.

The planning, control and execution of eye movements in 3D space relies on a distributed system of cortical and subcortical brain regions. Within this network, the Eye Fields have been described in animals as cortical regions in which electrical stimulation is able to trigger eye movements and influence their latency or accuracy. This review will focus on the Frontal Eye Field (FEF) a hub region located in Humans in the vicinity of the pre-central sulcus and the dorsal-most portion of the superior frontal sulcus. The straightforward localization of the FEF through electrical stimulation in animals is difficult to translate to the healthy human brain, particularly with non-invasive neuroimaging techniques. Hence, in the first part of this review, we will describe attempts made to characterize the anatomical localization of this area in the human brain. The outcome of functional Magnetic Resonance Imaging (fMRI), Magneto-encephalography (MEG) and particularly, non-invasive mapping methods such a Transcranial Magnetic Stimulation (TMS) will be described and the variability of FEF localization across individuals and mapping techniques will be discussed. In the second part of this review, we will address the role of the FEF. We will explore its involvement both in the physiology of fixation, saccade, pursuit and vergence movements and in associated cognitive processes such as attentional orienting, visual awareness and perceptual modulation. Finally in the third part, we will review recent evidence suggesting the high level of malleability and plasticity of these regions and associated networks to non-invasive stimulation. The exploratory, diagnostic and therapeutic interest of such interventions for the modulation and improvement of perception in 3D space will be discussed.

Many common words have spatial associations (e.g., “bird,” “jump”) that, counterintuitively, hinder identification of visual targets at their associated location. For example, “bird” hinders identification at the top of a display. This spatial interference has been attributed to perceptual competition: “bird” shifts attention upward and evokes the perceptual representation of a bird, which impairs identification of an unrelated target by preoccupying the visual system. We propose an alternative explanation based on perceptual matching: target objects and locations are coded independently for their congruence with the cue word, and codes that are inconsistent with one another hinder identification. Two experiments demonstrated that whereas semantically mismatching targets elicit spatial interference, semantically matching targets elicit spatial facilitation. Two further experiments demonstrated that cue words of strong (e.g., “bird”) and weak (e.g., “arise”) visual strength and imageability elicited equivalent spatial interference. Results suggest that spatial interference is attributable to perceptual matching rather than perceptual competition. Moreover, results supported a graded model of perceptual matching, whereby target identification times are proportional to the physical distance between the expected (i.e., associated) and observed (i.e., actual) target locations. [ABSTRACT FROM AUTHOR]

People with social anxiety disorder (SAD) exhibit an attentional bias for threat (AB). Nevertheless, the focus on AB for emotional stimuli has led to neglect the exploration of basic attention deficits for non-emotional material among SAD patients. This study aimed to investigate the integrity of the attentional system in SAD. The Attention Network Test was used to precisely explore attentional deficits, and centrally the differential deficit across the three attentional networks, namely alerting (allowing to achieve and maintain a state of alertness), orienting (allowing to select information from sensory input by engaging or disengaging attention to one stimulus among others and/or shifting the attentional resources from one stimulation to another), and executive control (involving the top-down control of attention and allowing to resolve response conflicts). Twenty-five patients with SAD were compared to 25 matched controls. SAD patients exhibited a specific impairment for the orienting network ( p <0.001) but preserved performance for the alerting and executive networks. Complementary analyses revealed that this impairment may result from a faster attentional engagement to task-irrelevant material. The orienting impairment was highly correlated with the intensity of the social anxiety symptoms, but did not correlate either with trait-anxiety, state-anxiety, or depressive symptoms. [ABSTRACT FROM AUTHOR]

This study assessed whether numerical magnitude affects the setting of basic spatial coordinates and reference frames, namely the subjective straight ahead. Three tasks were given to 24 right-handed healthy participants: a proprioceptive and a visuo-proprioceptive task, requiring pointing to the subjective straight ahead, and a visual task, requiring a perceptual judgment about the straight ahead position of a light moving left-to-right, or right-to-left. A control task, requiring the bisection of rods of different lengths, was also given. The four tasks were performed under conditions of passive auditory numerical (i.e., listening to small, 2, and large, 8, numbers), and neutral auditory-verbal (blah) stimulation. Numerical magnitude modulates the participants’ deviations in the visual straight ahead task, when the movement of the light is from left to right, with the small number bringing about a leftward deviation, the large number a rightward deviation. This result suggests that the spatial effects induced by the activation of the mental number line extend to an egocentric frame of reference. A similar directional modulation was found in the rod bisection task, in line with previous evidence. No effects of numerical magnitude were found on the proprioceptive and visuo-proprioceptive straight ahead tasks. These results suggest that the spatial effects induced by the activation of the mental number line extend to an egocentric frame of reference but only when a portion of horizontal space has to be actively explored.

Background: Children with unilateral Cerebral Palsy (CP) often show diminished awareness of the remaining capacity of their affected upper limb. This phenomenon is known as Developmental Disregard (DD). DD has been explained by operant conditioning. Alternatively, DD can be described as a developmental delay resulting from a lack of use of the affected hand during crucial developmental periods. We hypothesize that this delay is associated with a general delay in executive functions (EF) related to motor behavior, also known as motor EFs. Methods: Twenty-four children with unilateral CP participated in this cross-sectional study, twelve of them diagnosed with DD. To test motor EFs, a modified go/nogo task was presented in which cues followed by go- or nogo-stimuli appeared at either the left or right side of a screen. Children had to press a button with the hand corresponding to the side of stimulus presentation. Apart from response accuracy, Event-Related Potentials (ERPs) extracted from the ongoing EEG were used to register covert cognitive processes. ERP N1, P2, N2, and P3 components elicited by cue-, go-, and nogo-stimuli were further analyzed to differentiate between different covert cognitive processes. Results: Children with DD made more errors. With respect to the ERPs, the P3 component to go-stimuli was enhanced in children with DD. This enhancement was related to age, such that younger children with DD showed stronger enhancements. In addition, in DD the N1 component to cue- and go-stimuli was decreased. Conclusions: The behavioral results show that children with DD experience difficulties when performing the task. The finding of an enhanced P3 component to go-stimuli suggests that these difficulties are due to increased mental effort preceding movement. As age in DD mediated this enhancement, it seems that this increased mental effort is related to a developmental delay. The additional finding of a decreased N1 component in DD furthermore suggests a general diminished visuo-spatial attention. This effect reveals that DD might be a neuropsychological phenomenon similar to post-stroke neglect syndrome that does not resolve during development. These findings suggest that therapies aimed at reducing neglect could be a promising addition to existing therapies for DD. [ABSTRACT FROM AUTHOR]

The planning, control and execution of eye movements in 3D space relies on a distributed system of cortical and subcortical brain regions. Within this network, the Eye Fields have been described in animals as cortical regions in which electrical stimulation is able to trigger eye movements and influence their latency or accuracy. This review focuses on the Frontal Eye Field (FEF) a "hub" region located in Humans in the vicinity of the pre-central sulcus and the dorsal-most portion of the superior frontal sulcus. The straightforward localization of the FEF through electrical stimulation in animals is difficult to translate to the healthy human brain, particularly with non-invasive neuroimaging techniques. Hence, in the first part of this review, we describe attempts made to characterize the anatomical localization of this area in the human brain. The outcome of functional Magnetic Resonance Imaging (fMRI), Magneto-encephalography (MEG) and particularly, non-invasive mapping methods such a Transcranial Magnetic Stimulation (TMS) are described and the variability of FEF localization across individuals and mapping techniques are discussed. In the second part of this review, we will address the role of the FEF. We explore its involvement both in the physiology of fixation, saccade, pursuit, and vergence movements and in associated cognitive processes such as attentional orienting, visual awareness and perceptual modulation. Finally in the third part, we review recent evidence suggesting the high level of malleability and plasticity of these regions and associated networks to non-invasive stimulation. The exploratory, diagnostic, and therapeutic interest of such interventions for the modulation and improvement of perception in 3D space are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Interhemispheric inhibition of visuo-spatial attention was studied. [•] Two targets in left and right streams were embedded in standard or easy distractors. [•] T2 was better identified when T1 identification in the other stream was facilitated. [•] Dynamic changes in attention allocation were studied by means of ERPs. [•] Results are interpreted in terms of released interhemispheric inhibition. [ABSTRACT FROM AUTHOR]

The role of attention in visual word recognition and reading aloud is a long debated issue. Studies of both developmental and acquired reading disorders provide growing evidence that spatial attention is critically involved in word reading, in particular for the phonological decoding of unfamiliar letter strings. However, studies on healthy participants have produced contrasting results. The aim of this study was to investigate how the allocation of spatial attention may influence the perception of letter strings in skilled readers. High frequency words (HFWs), low frequency words and pseudowords were briefly and parafoveally presented either in the left or the right visual field. Attentional allocation was modulated by the presentation of a spatial cue before the target string. Accuracy in reporting the target string was modulated by the spatial cue but this effect varied with the type of string. For unfamiliar strings, processing was facilitated when attention was focused on the string location and hindered when it was diverted from the target. This finding is consistent the assumptions of the CDP+ model of reading aloud, as well as with familiarity sensitivity models that argue for a flexible use of attention according with the specific requirements of the string. Moreover, we found that processing of HFWs was facilitated by an extra-large focus of attention. The latter result is consistent with the hypothesis that a broad distribution of attention is the default mode during reading of familiar words because it might optimally engage the broad receptive fields of the highest detectors in the hierarchical system for visual word recognition. [ABSTRACT FROM AUTHOR]

Abstract: The causal ability of pre-target FEF activity to modulate visual detection for perithreshold stimuli has been recently demonstrated in humans by means of non-invasive neurostimulation. Yet in spite of the network-distributed effects of these type of techniques, the white matter (WM) tracts and distant visual nodes contributing to such behavioral impact remain unknown. We hereby used individual data from a group of healthy human subjects, who received time-locked pulses of active or sham Transcranial Magnetic Stimulation (TMS) to the right Frontal Eye Field (FEF) region, and experienced increases in visual detection sensitivity. We then studied the extent to which interindividual differences in visual modulation might be dependent on the WM patterns linking the targeted area to other regions relevant for visuo-attentional behaviors. We report a statistically significant correlation between the probability of connection in a right fronto-tectal pathway (FEF-Superior Colliculus) and the modulation of visual sensitivity during a detection task. Our findings support the potential contribution of this pathway and the superior colliculus in the mediation of visual performance from frontal regions in humans. Furthermore, we also show the ability of a TMS/DTI correlational approach to contribute to the disambiguation of the specific long-range pathways driving network-wide neurostimulatory effects on behavior, anticipating their future role in guiding a more efficient use of focal neurostimulation. [Copyright &y& Elsevier]

Numbers induce shifts of spatial attention on the left or the right sides of external space as a function of their magnitude. However, whether this number-space association is restricted to the linear horizontal extensions, or extends to the whole visual scene, is still an open question. This study investigates, by means of a cancellation paradigm, the influence of numerical magnitude during scanning tasks in which participants freely explore complex visual scenes unconstrained towards either the horizontal or the vertical unidimensional axes. Five cancellation tasks were adapted in which Arabic digits were used as targets or distracters, in structured (lines and columns) or unstructured visual displays, with a smaller (2 or 3 types of distracters) or larger (10 or more types of distracters) sets of stimuli. Results show that the participants' hits distribution was a function of number magnitude: shifted on the left for small and on the right for large numbers. This effect was maximised when numerical cues were sparse, randomly arranged and, critically, irrelevant to the task. Overall, this study provides novel evidence from visuo-spatial exploratory cancellation tasks for an attentional shift induced by number magnitude. [ABSTRACT FROM AUTHOR]

Abstract: Number processing interacts with space encoding in a wide variety of experimental paradigms. Most intriguingly, the passive viewing of uninformative number symbols can shift visuo-spatial attention to different target locations according to the number magnitude, i.e., small/large numbers facilitate processing of left/right targets, respectively. The brain architecture dedicated to these attention shifts associated with numbers remains unknown. Evoked potential recordings indicate that both early and late stages are involved in this spatio-numerical interaction, but the neuro-functional anatomy needs to be specified. Here we use, for the first time, functional magnetic resonance imaging (fMRI) to investigate attentional orienting following uninformative Arabic digits. We show that BOLD response in occipital visual regions is modulated by the congruency between digit magnitude (small/large) and target side (left/right). Additionally, we report higher BOLD responses following large (8, 9) compared to small (1, 2) digits in two bilateral parietal regions, yielding a significant effect of digit magnitude. We propose and discuss the view that encoding of semantic representations related to number symbols in parietal cortex leads to shifts in visuo-spatial attention and enhances visual processing in the occipital cortex according to number-space congruency rules. [Copyright &y& Elsevier]

Abstract: Subitizing is the immediate apprehension of the exact number of items in small sets. Despite more than a 100years of research around this phenomenon, its nature and origin are still unknown. One view posits that it reflects a number estimation process common for small and large sets, which precision decreases as the number of items increases, according to Weber’s law. Another view proposes that it reflects a non-numerical mechanism of visual indexing of multiple objects in parallel that is limited in capacity. In a previous research we have gathered evidence against the Weberian estimation hypothesis. Here we provide first direct evidence for the alternative object indexing hypothesis, and show that subitizing reflects a domain general mechanism shared with other tasks that require multiple object individuation. [Copyright &y& Elsevier]

Background and aim: Visuo-spatial attention is an ability by which a portion of visuo-spatial space is selected for efficient processing of the information orienting from it. People show a normal bias in visuo-spatial attention. The direction of this bias in Attention deficit Hyperactivity disorder (ADHD) is different from normal people's bias. Some cases diagnosed with ADHD can show a significant inattention in one side of the space, which is called unilateral neglect. The aim of this study is to investigate on how the visou-spatial bias is in children with ADHD. Materials and Methods: In this cross-sectional study, fifteen children (7-10 years) were classified with ADHD-combined type (ADHD-C) and 15 children were matched for age, gender and IQ. Samples had been chosen through simple random sampling and they did Wechsler Intelligence Scale for children (WISC-IV) and also the Edinburgh Handedness Inventory for assessing whether they had inclusion criteria or not. For participants, visuo-spatial attention was assessed using the Star Cancellation Test. Results: The results suggest that, there is a significant difference between ADHD-C groups performance and control group's performance in the Star Cancellation Test (p<0.05). Unilateral neglect recognized in ADHD-C group and it was in the left half of the space. Conclusion: There is a significant difference in visuo-spatial attention between ADHD group and control group. Moreover, unilateral neglect which has seen in some ADHD-C cases should consider as an important item in this disorder. Further research in this area is needed. [ABSTRACT FROM AUTHOR]

Neglect dyslexia is a reading disorder often associated with right-sided brain lesions. In reading single words, errors are mostly substitutions or omissions of letters that occupy the left-sided positions. Typically, these errors have been thought to depend on a single mechanism. Conversely, we propose that they are due to different mechanisms. In particular, a visuo-spatial mechanism is responsible for omissions and a perceptual integration process for substitution errors. We measured the performance of six patients with both neglect and neglect dyslexia, analyzing their reading errors as a function of letter spacing. According to our conjecture, letter spacing should increase omissions by moving part of the string further in the unattended space, while it should reduce substitutions by restoring the integration processes. Furthermore, we predict that letter spacing should be more effective with pseudowords compared to words, in that in this latter case lexical effects are supposed to influence attentional and perceptual processes. Accordingly, we found that for pseudowords only the two types of errors are differently affected by this manipulation and only omissions correlate with the severity of the disorder in visuo-spatial tasks. [ABSTRACT FROM AUTHOR]

Abstract: Several studies point to prism adaptation as an effective tool for the rehabilitation of hemispatial neglect. However, some recent reports failed to show a significant amelioration of neglect after prism adaptation as compared to control treatments. This apparent contradiction might reflect important differences in the procedures used for treatment. Here we compare the effects of two treatments (performed for 10 sessions, over 2 weeks) in two groups of patients, based either on a Terminal (TPA) or a Concurrent (CPA) prism adaptation procedure. During TPA only the final part of the pointing movement is visible and prism adaptation relies most strongly on a strategic recalibration of visuomotor eye–hand coordinates. In contrast, during CPA the second half of the pointing movement is visible, and thus adaptation mainly consists of a realignment of proprioceptive coordinates. The present results show that both TPA and CPA treatments induced a greater improvement of neglect as compared to a control treatment of pointing without prisms. However, neglect amelioration was higher for patients treated with TPA than for those treated with CPA. At the same time, the TPA treatment induced a stronger deviation of eye movements toward the left, neglected, field as compared to the CPA treatment. Interestingly, in TPA patients the visuomotor and oculomotor effects of the treatment were directly related to the patients’ ability to compensate for the optical deviation induced by prism during pointing (i.e., Error reduction effect). In summary, prism adaptation seems particularly effective for the recovery of visuo-spatial neglect when conducted with a procedure stressing a correction of visuomotor eye–hand coordinates, i.e., with a TPA procedure. The present observations may help to better understand the mechanisms underlying prism-induced recovery from neglect and the procedural basis for some of the contradictory results obtained when using this rehabilitative strategy. [Copyright &y& Elsevier]

The paper reviews the contribution of functional neuroimaging investigations (using single photon emission tomography, positron emission tomography and functional magnetic resonance) to the study of the neural mechanisms of recovery in patients with unilateral spatial neglect due to stroke. In addition, it highlights the important contribution of Luigi Pizzamiglio's experimental work in establishing a theoretical framework for the interpretation of imaging findings. The main tenet of this conception is that the brain reorganisation associated to recovery results from the engagement of both ipsilesional and contralesional brain areas, which in normal subjects are associated to task-relevant processes, such as oculomotor behaviour and visuo-spatial attentional shifts. [ABSTRACT FROM AUTHOR]

The right temporoparietal junction (rTPJ) is a polysensory cortical area that plays a key role in perception and awareness. Neuroimaging evidence shows activation of rTPJ in intersensory and sensorimotor conflict situations, but it remains unclear whether this activity reflects detection or resolution of such conflicts. To address this question, we manipulated the relationship between touch and vision using the so-called mirror- box illusion. Participants' hands lay on either side of a mirror, which occluded their left hand and reflected their right hand, but created the illusion that they were looking directly at their left hand. The experimenter simultaneously touched either the middle (D3) or the ring finger (D4) of each hand. Participants judged, which finger was touched on their occluded left hand. The visual stimulus corresponding to the touch on the right hand was therefore either congruent (same finger as touch) or incongruent (different finger from touch) with the task-relevant touch on the left hand. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the rTPJ immediately after touch. Accuracy in localizing the left touch was worse for D4 than for D3, particularly when visual stimulation was incongruent. However, following TMS, accuracy improved selectively for D4 in incongruent trials, suggesting that the effects of the conflicting visual information were reduced. These findings suggest a role of rTPJ in detecting, rather than resolving, intersensory conflict. [ABSTRACT FROM AUTHOR]

Phonological skills are foundational of reading acquisition and impaired phonological processing is widely assumed to characterize dyslexic individuals. However, reading by phonological decoding also requires rapid selection of sublexical orthographic units through serial attentional orienting, and recent studies have shown that visual spatial attention is impaired in dyslexic children. Our study investigated these different neurocognitive dysfunctions, before reading acquisition, in a sample of preschoolers including children with (N=20) and without (N=67) familial risk for developmental dyslexia. Children were tested on phonological skills, rapid automatized naming, and visual spatial attention. At-risk children presented deficits in both visual spatial attention and syllabic segmentation at the group level. Moreover, the combination of visual spatial attention and syllabic segmentation scores was more reliable than either single measure for the identification of at-risk children. These findings suggest that both visuo-attentional and perisylvian-auditory dysfunctions might adversely affect reading acquisition, and may offer a new approach for early identification and remediation of developmental dyslexia. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]