Neural processes involved in directing attention

Decoding Visual Spatial Attention Control

In models of visual spatial attention control, it is commonly held that top-down control signals originate in the dorsal attention network, propagating to the visual cortex to modulate baseline neural activity and bias sensory processing. However, the precise distribution of these top-down influences across different levels of the visual hierarchy is debated. In addition, it is unclear whether these baseline neural activity changes translate into improved performance. We analyzed attention-related baseline activity during the anticipatory period of a voluntary spatial attention task, using two independent functional magnetic resonance imaging datasets and two analytic approaches. First, as in prior studies, univariate analysis showed that covert attention significantly enhanced baseline neural activity in higher-order visual areas contralateral to the attended visual hemifield, while effects in lower-order visual areas (e.g., V1) were weaker and more variable. Second, in contrast, multivariate pattern analysis (MVPA) revealed significant decoding of attention conditions across all visual cortical areas, with lower-order visual areas exhibiting higher decoding accuracies than higher-order areas. Third, decoding accuracy, rather than the magnitude of univariate activation, was a better predictor of a subject's stimulus discrimination performance. Finally, the MVPA results were replicated across two experimental conditions, where the direction of spatial attention was either externally instructed by a cue or based on the participants' free choice decision about where to attend. Together, these findings offer new insights into the extent of attentional biases in the visual hierarchy under top-down control and how these biases influence both sensory processing and behavioral performance.

Neural mechanisms of object prioritization in vision

Selective attention is widely thought to be sensitive to visual objects. This is commonly demonstrated in cueing studies, which show that when attention is deployed to a known target location that happens to fall on a visual object, responses to targets that unexpectedly appear at other locations on that object are faster and more accurate, as if the object in its entirety has been visually prioritized. However, this notion has recently been challenged by results suggesting that putative object-based effects may reflect the influence of hemifield anisotropies in attentional deployment, or of unacknowledged influences of perceptual complexity and visual clutter. Studies employing measures of behaviour provide limited opportunity to address these challenges. Here, we used EEG to directly measure the influence of task-irrelevant objects on the deployment of visual attention. We had participants complete a simple visual cueing task involving identification of a target that appeared at either a cued location or elsewhere. Throughout each experimental trial, displays contained task-irrelevant rectangle stimuli that could be oriented horizontally or vertically. We derived two cue-elicited indices of attentional deployment-lateralized alpha oscillations and the ADAN component of the event-related potential-and found that these were sensitive to the otherwise irrelevant orientation of the rectangles. Our results demonstrate that the allocation of visual attention is influenced by objects boundaries, supporting models of object-based attentional prioritization.

Decoding Visual Spatial Attention Control

In models of visual spatial attention control, it is commonly held that top-down control signals originate in the dorsal attention network, propagating to the visual cortex to modulate baseline neural activity and bias sensory processing. However, the precise distribution of these top-down influences across different levels of the visual hierarchy is debated. In addition, it is unclear whether these changes in baseline neural activity directly translate into improved performance. We analyzed attention-related baseline activity during the anticipatory period of a trial-by-trial voluntary spatial attention task, using two independent fMRI datasets, and two different analytic approaches. First, as in prior studies, univariate analysis showed that covert attention significantly enhanced baseline neural activity in higher-order visual areas contralateral to the attended visual hemifield, while effects in lower-order visual areas (e.g., V1) were weaker and more variable. Second, in contrast, multivariate pattern analysis (MVPA) revealed significant decoding of attention conditions across all visual cortical areas, with lower-order visual areas exhibiting higher decoding accuracies than higher-order areas. Third, decoding accuracy, rather than the magnitude of univariate activation, was a better predictor of a subject's stimulus discrimination performance. Finally, the MVPA results were replicated across two experimental conditions, where the direction of spatial attention was either externally instructed by a cue or based on the participants free choice decision about where to attend. Together, these findings offer new insights into the extent of attentional biases in the visual hierarchy under top-down control, and how these biases influence both sensory processing and behavioral performance.

Highlights

Multivariate pattern analysis revealed the presence of top-down attentional biasing signals in all areas of the visual hierarchy whereas univariate analysis was not able to reveal the full extent of attentional biasing in the visual cortex.The decoding accuracy derived from the MVPA analysis but not the magnitude difference derived from the univariate analysis predicted the subject's behavioral performance in stimulus discrimination.The MVPA results were consistent across two experimental conditions where the direction of spatial attention was driven either by external instructions or from purely internal decisions.

Enhancing perceptual, attentional, and working memory demands through variable practice schedules: insights from high-density EEG multi-scale analyses

Contextual interference (CI) enhances learning by practicing motor tasks in a random order rather than a blocked order. One hypothesis suggests that the benefits arise from enhanced early perceptual/attentional processes, while another posits that better learning is due to highly activated mnemonic processes. We used high-density electroencephalography in a multi-scale analysis approach, including topographic analyses, source estimations, and functional connectivity, to examine the intertwined dynamics of attentional and mnemonic processes within short time windows. We recorded scalp activity from 35 participants as they performed an aiming task at three different distances, under both random and blocked conditions using a crossover design. Our results showed that topographies associated with processes related to perception/attention (N1, P3a) and working memory (P3b) were more pronounced in the random condition. Source estimation analyses supported these findings, revealing greater involvement of the perceptual ventral pathway, anterior cingulate and parietal cortices, along with increased functional connectivity in ventral alpha and frontoparietal theta band networks during random practice. Our results suggest that CI is driven, in the random compared to the blocked condition, by enhanced specific processes such as perceptual, attentional, and working memory processes, as well as large-scale functional networks sustaining more general attentional and executive processes.

Attachment style and attention bias to emotional information: The moderating effect of stress, stimulus characteristics, and attention stage

OBJECTIVE

We examined whether insecurely attached individuals exhibit an attention bias to emotional information, and further tested the potential moderating role of stress, information valence, information attachment relevance, and attention stage.

BACKGROUND

Attachment style can predict people's attention to emotional information. However, the empirical findings are inconsistent, making it difficult to determine the associations between attachment style and attention bias to emotional information.

METHOD

We included 68 studies (N = 5417) across 46 published and unpublished articles (the initial pool was 627 articles) in the meta-analysis.

RESULTS

People high on attachment avoidance exhibited decreased attention toward emotional stimuli (d = -0.129, p = 0.020), which was not affected by stress, information valence, information attachment relevance, or attention stage. Conversely, people high on attachment anxiety exhibited increased attention toward emotional stimuli, especially under stress, if the information was attachment-related, and during late-stage attentional processing. They exhibited an early bias away from and a late bias toward emotional information, which was intensified under stress.

CONCLUSION

Our findings support the proposition that people high on attachment avoidance use deactivating strategies in attentional processing; whereas people high on attachment anxiety use hyperactivating strategies, especially when resources are limited (under stress). When resources are available, and it is relatively early in the process, people high on attachment anxiety respond similarly to those high on attachment avoidance.

Sustained attention operates via dissociable neural mechanisms across different eccentric locations

In primates, foveal and peripheral vision have distinct neural architectures and functions. However, it has been debated if selective attention operates via the same or different neural mechanisms across eccentricities. We tested these alternative accounts by examining the effects of selective attention on the steady-state visually evoked potential (SSVEP) and the fronto-parietal signal measured via EEG from human subjects performing a sustained visuospatial attention task. With a negligible level of eye movements, both SSVEP and SND exhibited the heterogeneous patterns of attentional modulations across eccentricities. Specifically, the attentional modulations of these signals peaked at the parafoveal locations and such modulations wore off as visual stimuli appeared closer to the fovea or further away towards the periphery. However, with a relatively higher level of eye movements, the heterogeneous patterns of attentional modulations of these neural signals were less robust. These data demonstrate that the top-down influence of covert visuospatial attention on early sensory processing in human cortex depends on eccentricity and the level of saccadic responses. Taken together, the results suggest that sustained visuospatial attention operates differently across different eccentric locations, providing new understanding of how attention augments sensory representations regardless of where the attended stimulus appears.

Acute hypoxia alters visuospatial attention orienting: an electrical neuroimaging study

Our study investigated the effects of hypoxia on visuospatial attention processing during preparation for a single/double-choice motor response. ERPs were recorded in two sessions in which participants breathed either ambient-air or oxygen-impoverished air. During each session, participants performed four cue-target attention orienting and/or alerting tasks. Replicating the classic findings of valid visuospatial attentional orienting modulation, ERPs to pre-target cues elicited both an Anterior directing attention negativity (ADAN)/CNV and a posterior Late directing attention positivity (LDAP)/TP, which in ambient air were larger for attention orienting than for alerting. Hypoxia increased the amplitude of both these potentials in the spatial orienting conditions for the upper visual hemifield, while, for the lower hemifield, it increased ADAN/CNV, but decreased LDAP/TP for the same attention conditions. To these ERP changes corresponded compensatory enhanced activation of right anterior cingulate cortex, left superior parietal lobule and frontal gyrus, as well as detrimental effects of hypoxia on behavioral overt performance. Together, these findings reveal for the first time, to our knowledge, that (1) these reversed alterations of the activation patterns during the time between cue and target occur at a larger extent in hypoxia than in air, and (2) acute normobaric hypoxia alters visuospatial attention orienting shifting in space.

The Electrophysiological Markers of Statistically Learned Attentional Enhancement: Evidence for a Saliency-based Mechanism

It is well established that attention can be sharpened through the process of statistical learning (e.g., visual search becomes faster when targets appear at high-relative-to-low probability locations). Although this process of statistically learned attentional enhancement differs behaviorally from the well-studied top-down and bottom-up forms of attention, relatively little work has been done to characterize the electrophysiological correlates of statistically learned attentional enhancement. It thus remains unclear whether statistically learned enhancement recruits any of the same cognitive mechanisms as top-down or bottom-up attention. In the current study, EEG data were collected while participants searched for an ambiguous unique shape in a visual array (the additional singleton task). Unbeknownst to the participants, targets appeared more frequently in one location in space (probability cuing). Encephalographic data were then analyzed in two phases: an anticipatory phase and a reactive phase. In the anticipatory phase preceding search stimuli onset, alpha lateralization as well as the Anterior Directing Attention Negativity and Late Directing Attention Positivity components-signs of preparatory attention known to characterize top-down enhancement-were tested. In the reactive phase, the N2pc component-a well-studied marker of target processing-was examined following stimuli onset. Our results showed that statistically learned attentional enhancement is not characterized by any of the well-known anticipatory markers of top-down attention; yet targets at high probability locations did reliably evoke larger N2pc amplitudes, a finding that is associated with bottom-up attention and saliency. Overall, our findings are consistent with the notion that statistically learned attentional enhancement increases the perceptual salience of items appearing at high-probability locations relative to low-probability locations.

On the Relevance of Posterior and Midfrontal Theta Activity for Visuospatial Attention

The aim of this study was to examine whether oscillatory activity in the theta-band is relevant for selective visuospatial attention when there is a need for the suppression of interfering and distracting information. A variant of the Eriksen flanker task was employed with bilateral arrays: one array consisting of a target and congruent or incongruent flankers and the second array consisting of neutral distractors. The bilateral arrays were preceded either by a 100% valid spatial cue or by a neutral cue. In the cue-target interval, a major burst in medial frontal theta power was observed, which was largest in the spatial cue condition. In the latter condition, additionally a posterior theta increase was observed that was larger over sites ipsilateral to the forthcoming target array. Functional connectivity analyses revealed that this pretarget posterior theta was related to the midfrontal theta. No such effects were observed in the neutral cue condition. After onset of the bilateral arrays, a major burst in posterior theta activity was observed in both cue conditions, which again was larger above sites ipsilateral to the target array. Furthermore, this posterior theta was in all cases related to the midfrontal theta. Taken together, the findings suggest that a fronto-posterior theta network plays an important role in the suppression of irrelevant and conflicting visual information. The results also suggest that the reciprocal relation between visuospatial attention and executive response control may be closer than commonly thought.

Sustained attention operates via dissociable neural mechanisms across different eccentric locations

In primates, foveal and peripheral vision have distinct neural architectures and functions. However, it has been debated if selective attention operates via the same or different neural mechanisms across eccentricities. We tested these alternative accounts by examining the effects of selective attention on the steady-state visually evoked potential (SSVEP) and the fronto-parietal signal measured via EEG from human subjects performing a sustained visuospatial attention task. With a negligible level of eye movements, both SSVEP and SND exhibited the heterogeneous patterns of attentional modulations across eccentricities. Specifically, the attentional modulations of these signals peaked at the parafoveal locations and such modulations wore off as visual stimuli appeared closer to the fovea or further away towards the periphery. However, with a relatively higher level of eye movements, the heterogeneous patterns of attentional modulations of these neural signals were less robust. These data demonstrate that the top-down influence of covert visuospatial attention on early sensory processing in human cortex depends on eccentricity and the level of saccadic responses. Taken together, the results suggest that sustained visuospatial attention operates differently across different eccentric locations, providing new understanding of how attention augments sensory representations regardless of where the attended stimulus appears.

The effects of pre-cue alpha and cueing strategy on age-related deficits in post-cue alpha activity and target processing during visual spatial attention

Electroencephalography alpha-band (8-13 Hz) activity during visual spatial attention declines in normal aging. We recently reported the impacts of pre-cue baseline alpha and cueing strategy on post-cue anticipatory alpha activity and target processing in visual spatial attention (Wang et al., Cerebral Cortex, 2023). However, whether these factors affected aging effects remains unaddressed. We investigated this issue in two independent experiments (n = 114) with different cueing strategies (instructional vs. probabilistic). When median-splitting young adults (YA) by their pre-cue alpha power, we found that older adults exhibited similar pre-cue and post-cue alpha activity as YA with lower pre-cue alpha, and only YA with higher pre-cue alpha showed significant post-cue alpha activity, suggesting that diminished anticipatory alpha activity was not specific to aging but likely due to a general decrease with baseline alpha. Moreover, we found that the aging effects on cue-related event-related potentials were dependent on cueing strategy but were relatively independent of pre-cue alpha. However, age-related deficits in target-related N1 attentional modulation might depend on both pre-cue alpha and cueing strategy. By considering the impacts of pre-cue alpha and cueing strategy, our findings offer new insights into age-related deficits in anticipatory alpha activity and target processing during visual spatial attention.

EEG correlates of anticipatory attention and target processing in children and adults during visual spatial attention

The ability of attentional orienting has been suggested to keep developing throughout childhood. Electroencephalography (EEG) studies have shown that 6-10 year old children exhibit lateralized alpha-band (8-13 Hz) activity and event-related potentials (ERPs) that are classic markers of spatial attentional orienting in adults. However, the lack of a direct comparison of these EEG correlates between children and adults in the same experiment made it difficult to evaluate developmental effects on neural activity throughout attentional stages. This study aimed to directly compare cue-related alpha activity and ERPs for the anticipatory attention stage and target-related ERPs for the target processing stage between healthy children and adults. Participants, including 19 children (6-10 years) and 23 adults (18-34 years), successfully completed a visual spatial attention task, although children responded more slowly and less consistently than adults. Both age groups exhibited significant cue-related alpha lateralization and ERPs (EDAN, ADAN, and LDAP) during anticipatory attention and significant attentional modulation of target-related N1 during target processing. However, no significant difference was found in the magnitude of attentional modulation of these EEG correlates between children and adults. These findings suggest that the neural underpinnings of anticipatory attention and target processing during visual spatial attention could have been largely developed in 6-10 year old children.

Eye movements disrupt EEG alpha-band coding of behaviorally relevant and irrelevant spatial locations held in working memory

Oscillations in the alpha frequency band (∼8-12 Hz) of the human electroencephalogram play an important role in supporting selective attention to visual items and maintaining their spatial locations in working memory (WM). Recent findings suggest that spatial information maintained in alpha is modulated by interruptions to continuous visual input, such that attention shifts, eye closure, and backward masking of the encoded item cause reconstructed representations of remembered locations to become degraded. Here, we investigated how another common visual disruption-eye movements-modulates reconstructions of behaviorally relevant and irrelevant item locations held in WM. Participants completed a delayed estimation task, where they encoded and recalled either the location or color of an object after a brief retention period. During retention, participants either fixated at the center or executed a sequence of eye movements. Electroencephalography (EEG) was recorded at the scalp and eye position was monitored with an eye tracker. Inverted encoding modeling (IEM) was applied to reconstruct location-selective responses across multiple frequency bands during encoding and retention. Location-selective responses were successfully reconstructed from alpha activity during retention where participants fixated at the center, but these reconstructions were disrupted during eye movements. Recall performance decreased during eye-movements conditions but remained largely intact, and further analyses revealed that under specific task conditions, it was possible to reconstruct retained location information from lower frequency bands (1-4 Hz) during eye movements. These results suggest that eye movements disrupt maintained spatial information in alpha in a manner consistent with other acute interruptions to continuous visual input, but this information may be represented in other frequency bands.NEW & NOTEWORTHY Neural oscillations in the alpha frequency band support selective attention to visual items and maintenance of their spatial locations in human working memory. Here, we investigate how eye movements disrupt representations of item locations held in working memory. Although it was not possible to recover item locations from alpha during eye movements, retained location information could be recovered from select lower frequency bands. This suggests that during eye movements, stored spatial information may be represented in other frequencies.

The Effects of Directional and Non-Directional Stimuli during a Visuomotor Task and Their Correlation with Reaction Time: An ERP Study

Different visual stimuli can capture and shift attention into different directions. Few studies have explored differences in brain response due to directional (DS) and non-directional visual stimuli (nDS). To explore the latter, event-related potentials (ERP) and contingent negative variation (CNV) during a visuomotor task were evaluated in 19 adults. To examine the relation between task performance and ERPs, the participants were divided into faster (F) and slower (S) groups based on their reaction times (RTs). Moreover, to reveal ERP modulation within the same subject, each recording from the single participants was subdivided into F and S trials based on the specific RT. ERP latencies were analysed between conditions ((DS, nDS); (F, S subjects); (F, S trials)). Correlation was analysed between CNV and RTs. Our results reveal that the ERPs' late components are modulated differently by DS and nDS conditions in terms of amplitude and location. Differences in ERP amplitude, location and latency, were also found according to subjects' performance, i.e., between F and S subjects and trials. In addition, results show that the CNV slope is modulated by the directionality of the stimulus and contributes to motor performance. A better understanding of brain dynamics through ERPs could be useful to explain brain states in healthy subjects and to support diagnoses and personalized rehabilitation in patients with neurological diseases.

Anticipatory attention is a stable state induced by transient control mechanisms

Anticipatory attention is a neurocognitive state in which attention control regions bias neural activity in sensory cortical areas to facilitate the selective processing of incoming targets. Previous electroencephalographic (EEG) studies have identified event-related potential (ERP) signatures of anticipatory attention, and implicated alpha band (8-12 Hz) EEG oscillatory activity in the selective control of neural excitability in visual cortex. However, the degree to which ERP and alpha band measures reflect related or distinct underlying neural processes remains to be further understood. To investigate this question, we analyzed EEG data from 20 human participants performing a cued object-based attention task. We used support vector machine (SVM) decoding analysis to compare the attentional time courses of ERP signals and alpha band power. We found that ERP signals encoding attentional instructions are dynamic and precede stable attention-related changes in alpha power, suggesting that ERP and alpha power reflect distinct neural processes. We proposed that the ERP patterns reflect transient attentional orienting signals originating in higher order control areas, whereas the patterns of synchronized oscillatory neural activity in the alpha band reflect a sustained attentional state. These findings support the hypothesis that anticipatory attention involves transient top-down control signals that establish more stable neural states in visual cortex, enabling selective sensory processing.

Individual EEG profiling of attention deficits in left spatial neglect: A pilot study

Electrophysiological group studies in brain-damaged patients can be run to capture the EEG correlates of specific cognitive impairments. Nonetheless, this procedure is not adequate to characterize the inter-individual variability present in major neuropsychological syndromes. We tested the possibility of getting a reliable individual EEG characterization of deficits of endogenous orienting of spatial attention in right-brain damaged (RBD) patients with left spatial neglect (N+). We used a single-trial topographical analysis (STTA; [39] of individual scalp EEG topographies recorded during leftward and rightward orienting of attention with central cues in RBD patients with and without (N-) neglect and in healthy controls (HC). We found that the STTA successfully decoded EEG signals related to leftward and rightward orienting in five out of the six N+, five out of the six N- patients and in all the six HC. In agreement with findings from conventional average-group studies, successful classifications of EEG signals in N+ were observed during the 400-800 ms period post-cue-onset, which reflects preserved voluntary engagement of attention resources (ADAN component). These results suggest the possibility of acquiring reliable individual EEG profiles of neglect patients.

From Gaze Perception to Social Cognition: The Shared-Attention System

When two people look at the same object in the environment and are aware of each other's attentional state, they find themselves in a shared-attention episode. This can occur through intentional or incidental signaling and, in either case, causes an exchange of information between the two parties about the environment and each other's mental states. In this article, we give an overview of what is known about the building blocks of shared attention (gaze perception and joint attention) and focus on bringing to bear new findings on the initiation of shared attention that complement knowledge about gaze following and incorporate new insights from research into the sense of agency. We also present a neurocognitive model, incorporating first-, second-, and third-order social cognitive processes (the shared-attention system, or SAS), building on previous models and approaches. The SAS model aims to encompass perceptual, cognitive, and affective processes that contribute to and follow on from the establishment of shared attention. These processes include fundamental components of social cognition such as reward, affective evaluation, agency, empathy, and theory of mind.

Sustained visuospatial attention enhances lateralized anticipatory ERP activity in sensory areas

The existence of neural correlates of spatial attention is not limited to the reactive stage of stimulus processing: neural activities subtending spatial attention are deployed well ahead of stimulus onset. ERP evidence supporting this proactive (top-down) attentional control is based on trial-by-trial S1-S2 paradigms, where the onset of a directional cue (S1) indicates on which side attention must be directed to respond to an upcoming target stimulus (S2). Crucially, S1 onset trigger both attention and motor preparation, therefore, these paradigms are not ideal to demonstrate the effect of attention at preparatory stage of processing. To isolate top-down anticipatory attention, the present study used a sustained attention paradigm based on a steady cue that indicates the attended side constantly throughout an entire block of trials, without any onset of an attentional cue. The main result consists in the description of the attention effect on the visual negativity (vN) component, a growing neural activity starting before stimulus presentation in extrastriate visual areas. The vN was consistently lateralized in the hemisphere contralateral to the attended side, regardless of the hand to be used. At the opposite, the lateralized motor activity emerged long after, confirming that the hand-selection process followed the spatial attention orientation process. The present study confirms the anticipatory nature of the vN component and corroborate its role in terms of preparatory visuospatial attention.

Spatial Attention in Serial Order Working Memory: An EEG Study

Theoretical models explaining serial order processing link order information to specified position markers. However, the precise characteristics of position marking have remained largely elusive. Recent studies have shown that space is involved in marking serial position of items in verbal working memory (WM). Furthermore, it has been suggested, but not proven, that accessing these items involves horizontal shifts of spatial attention. We used continuous electroencephalography recordings to show that memory search in serial order verbal WM involves spatial attention processes that share the same electrophysiological signatures as those operating on the visuospatial WM and external space. Accessing an item from a sequence in verbal WM induced posterior “early directing attention negativity” and “anterior directing attention negativity” contralateral to the position of the item in mental space (i.e., begin items on the left; end items on the right). In the frequency domain, we observed posterior alpha suppression contralateral to the position of the item. Our results provide clear evidence for the involvement of spatial attention in retrieving serial information from verbal WM. Implications for WM models are discussed.

Neural mechanisms of eye gaze processing as a function of emotional expression and working memory load

The aim of the present study was to investigate the role of working memory load on the gaze cueing effect in high and low trait-anxious participants, using electroencephalography. Fearful and neutral faces predicted the location of a target, which was a digit that participants were asked to recall from a series encoded in each trial, in a modified version of the attentional cueing task. Working memory load impacted cueing irrespective of emotion and anxiety in analysis of reaction times. Lateralized EEG components then showed that effects of emotion were only apparent in high anxious individuals, with an initial hypervigilance to target locations cued by fearful faces, followed by a difficulty to disengage from these locations when targets appeared at uncued sites (P1). Enhanced amplitude following fearful faces was observed, when discriminative processes leading to response selection are implemented (N1). Conversely, all the effects of working memory load were independent of emotion in the low anxious group, where the shifting of attention directed by the gaze was only visible when enough resources were available in the working memory span. Working memory loads impacted the processing of gaze differently (P1) in low anxious participants, suggesting that top-down influence may play a role in this case.

Lateralized alpha activity and slow potential shifts over visual cortex track the time course of both endogenous and exogenous orienting of attention

Spatial attention can be oriented endogenously, based on current task goals, or exogenously, triggered by salient events in the environment. Based upon literature demonstrating differences in the time course and neural substrates of each type of orienting, these two attention systems are often treated as fundamentally distinct. However, recent studies suggest that rhythmic neural activity in the alpha band (8-13 Hz) and slow waves in the event-related potential (ERP) may emerge over parietal-occipital cortex following both endogenous and exogenous attention cues. To assess whether these neural changes index common processes of spatial attention, we conducted two within-subject experiments varying the two main dimensions over which endogenous and exogenous attention tasks typically differ: cue informativity (spatially predictive vs. non-predictive) and cue format (centrally vs. peripherally presented). This task design allowed us to tease apart neural changes related to top-down goals and those driven by the reflexive orienting of spatial attention, and examine their interactions in a novel hybrid cross-modal attention task. Our data demonstrate that both central and peripheral cues elicit lateralized ERPs over parietal-occipital cortex, though at different points in time, consistent with these ERPs reflecting the orienting of spatial attention. Lateralized alpha activity was also present across all tasks, emerging rapidly for peripheral cues and sustaining longer for spatially informative cues. Overall, these data indicate that distinct slow-wave ERPs index the spatial orienting of endogenous and exogenous attention, while lateralized alpha activity represents a common signature of visual-cortical biasing in anticipation of potential targets across both types of attention.

Phasic alerting facilitates endogenous orienting of spatial attention: Evidence from event-related lateralizations of the EEG

Alerting has been hypothesized to affect spatial orienting either by accelerating the speed of attentional shift toward the cued target location (the accelerating hypothesis) or by enhancing the orienting effect without changing its time course (the enhancing hypothesis). To investigate the neural underpinnings of the effect of phasic alerting on endogenous orienting, we recorded the electroencephalogram (EEG) in a variant of the spatial cueing task with a tone presented 100 ms before the cue as a phasic alerting signal, and calculated cue-evoked event-related lateralizations (ERLs) providing a precise assessment of preparatory visuospatial attention. Behavioral results showed that the spatial orienting effect was increased under the phasic alerting condition, as expected. The EEG results showed that an orienting-related ERL component called a late directing attention positivity (LDAP) had shorter onset latency and larger amplitude in the alerting condition than in the no-alerting (no-tone) condition. In conclusion, phasic alerting seems to both accelerate and enhance orienting-related preparatory modulations within the ventral visual stream.

Decoding attention control and selection in visual spatial attention

Event‐related potentials (ERPs) are used extensively to investigate the neural mechanisms of attention control and selection. The univariate ERP approach, however, has left important questions inadequately answered. We addressed two questions by applying multivariate pattern classification to multichannel ERPs in two cued visual spatial attention experiments (N = 56): (a) impact of cueing strategies (instructional vs. probabilistic) on attention control and selection and (b) neural and behavioral effects of individual differences. Following cue onset, the decoding accuracy (cue left vs. cue right) began to rise above chance level earlier and remained higher in instructional cueing (~80 ms) than in probabilistic cueing (~160 ms), suggesting that unilateral attention focus leads to earlier and more distinct formation of the attention control set. A similar temporal sequence was also found for target‐related processing (cued target vs. uncued target), suggesting earlier and stronger attention selection under instructional cueing. Across the two experiments: (a) individuals with higher cue‐related decoding accuracy showed higher magnitude of attentional modulation of target‐evoked N1 amplitude, suggesting that better formation of anticipatory attentional state leads to stronger modulation of target processing, and (b) individuals with higher target‐related decoding accuracy showed faster reaction times (or larger cueing effects), suggesting that stronger selection of task‐relevant information leads to better behavioral performance. Taken together, multichannel ERPs combined with machine learning decoding yields new insights into attention control and selection that complement the univariate ERP approach, and along with the univariate ERP approach, provides a more comprehensive methodology to the study of visual spatial attention.

Pre-motor deficits in left spatial neglect: An EEG study on Contingent Negative Variation (CNV) and response-related beta oscillatory activity

Right Brain Damaged patients with left spatial neglect (N+), are characterised by poor allocation of attention in the contralesional left side of space. In a recent study (Lasaponara et al., 2018) we showed during orienting of spatial attention with endogenous central cues, both the EEG markers reflecting the early phases of orienting (Early Directing Attention Negativity) and those reflecting the late setting-up of sensory facilitation in the visual cortex (Late Directing Attention Positivity) are disturbed in N+ when these patients attend the left side of space. In the healthy brain, endogenous cues also elicit EEG activity related to the preparation of manual responses to upcoming spatial targets. Here, we wished to expand on our previous findings and investigate the EEG correlates of cue-related response preparation in N+ patients. To this aim we investigated the Contingent Negative Variation (CNV) response and the pre-motor Beta-oscillatory activity evoked by spatially informative central cues during the performance of a Posner task. Due to concomitant contralesional motor impairments, N+ an N- patients performed the task only with the ipsilesional right-hand. Compared to healthy controls and patients without neglect, N+ displayed a pathological suppression of CNV component that was independent of cue direction. In addition, the amplitude of the CNV in response to right-pointing cues was positively correlated with neglect severity in line bisection. N+ also displayed a pathological enhancement of pre-motor Beta oscillations over the left hemisphere during the time period that preceded manual responses to targets in the left side of space, particularly to invalidly cued ones. Synchronization in the Beta-band (ERS) was also correlated with lower detection rate and slower RTs to Invalid targets in the left side of space. These results provide new insights on the premotor components of the spatial orienting deficits suffered by patients with left spatial neglect and can help improving its diagnosis and rehabilitation.

Deconstructing Reorienting of Attention: Cue Predictiveness Modulates the Inhibition of the No-target Side and the Hemispheric Distribution of the P1 Response to Invalid Targets

Orienting of attention produces a “sensory gain” in the processing of visual targets at attended locations and an increase in the amplitude of target-related P1 and N1 ERPs. P1 marks gain reduction at unattended locations; N1 marks gain enhancement at attended ones. Lateral targets that are preceded by valid cues also evoke a larger P1 over the hemisphere contralateral to the no-target side, which reflects inhibition of this side of space [Slagter, H. A., Prinssen, S., Reteig, L. C., & Mazaheri, A. Facilitation and inhibition in attention: Functional dissociation of pre-stimulus alpha activity, P1, and N1 components. Neuroimage, 125, 25–35, 2016]. To clarify the relationships among cue predictiveness, sensory gain, and the inhibitory P1 response, we compared cue- and target-related ERPs among valid, neutral, and invalid trials with predictive (80% valid/20% invalid) or nonpredictive (50% valid/50% invalid) directional cues. Preparatory facilitation over the visual cortex contralateral to the cued side of space (lateral directing attention positivity component) was reduced during nonpredictive cueing. With predictive cues, the target-related inhibitory P1 was larger over the hemisphere contralateral to the no-target side not only in response to valid but also in response to neutral and invalid targets: This result highlights a default inhibitory hemispheric asymmetry that is independent from cued orienting of attention. With nonpredictive cues, valid targets reduced the amplitude of the inhibitory P1 over the hemisphere contralateral to the no-target side whereas invalid targets enhanced the amplitude of the same inhibitory component. Enhanced inhibition was matched with speeded reorienting to invalid targets and drop in attentional costs. These findings show that reorienting of attention is modulated by the combination of cue-related facilitatory and target-related inhibitory activity.

Attention shifting and subliminal cueing under high attentional load: an EEG study using emotional faces

Emotional expressions and attentional processes interact such that emotion increases perceptual sensitivity in modality-specific brain areas leading to more efficient processing of the stimulus. In the current study, we asked the question of whether the emotional expressions can be processed subliminally when faces are attended but the emotional expression is irrelevant. We presented angry and neutral male and female faces supraliminally and subliminally to participants in an attention-shifting paradigm. Emotional expression was irrelevant to the task, but the gender of the face was predictive of the location of a subsequent target. Analysis of reaction times revealed that, in the supraliminal condition, targets appearing at validly cued locations produced quicker responses than targets at invalidly cued locations. Target-locked event-related potentials (ERPs) confirmed this result and showed that attention selection elicited higher responses at attended locations, as reflected by the N1 component. However, voluntary attention shifting was not triggered when the cue was not consciously perceived. No effects of emotion were observed following target presentation, suggesting that the high attentional load required by the experiment may have prevented the processing of emotion for undetectable faces, as demonstrated by the fact that, following cue onset, the N170 was modulated by emotion in supraliminal trials only. We therefore show that emotional expressions cannot be processed without awareness when faces are attended, but the emotional expression is irrelevant.

The attentional guidance of individual colours in increasingly complex displays

The use of colours is a prevalent and effective tool for improving design. Understanding the effect of colours on attention is crucial for designers that wish to understand how their interfaces will be used. Previous research has consistently shown that attention is biased towards colour. However, despite previous evidence indicating that colours should be treated individually, it has thus far not been investigated whether this difference is reflected in individual effects on attention. To address this, a visual search experiment was conducted that tested the attentional guidance of six individual colours (red,blue, green, yellow, orange, purple) in increasingly complex displays. Results showed that the individual colours differed significantly in their level of guidance of attention, and that these differences increased as the visual complexity of the display increased. Implications for visual design and future research on applying colour in visual attention research and design are discussed.

Large lateralized EDAN-like brain potentials in a gaze-shift detection task

Attentional cueing tasks using gaze direction as spatial cues have sometimes yielded an early directing attention negativity (EDAN) component in the ERP, presumably reflecting the initial orienting toward the cued location. However, other studies have failed to identify an EDAN component for gaze cues, yielding an inconsistent picture. In the present study, we re-examined the EDAN to gaze cueing, using a continuous task where the specific direction of the gaze changes was task irrelevant. Face stimuli changed gaze direction several times during each trial between direct, left-, and right-averted positions. Participants counted the number of gaze shifts during the trial. Results showed an unusually large EDAN-like ERP asymmetry at posterior scalp sites that was of similar amplitude for large and small gaze shifts into the periphery. Shifts from an averted position toward a direct gaze elicited a qualitatively similar but smaller effect than shifts into the periphery. Together, these findings shed new light on gaze-elicited spatial attention as they indicate a reflexive attention orienting, following the direction of gaze motion, even when the gaze direction itself is irrelevant for the task.

The role of the motion cue in the dynamic gaze-cueing effect: A study of the lateralized ERPs

When face was inverted, dynamic gaze cues could still effectively direct attention despite the disruption of configural face processing, but the static gaze cues could not. The present study investigated the role of the motion cue in the dynamic Gaze-Cueing Effect (GCE). With schematic and real faces, we employed the gaze-cueing paradigm to examine the differences among three kinds of cues (static gaze cue, dynamic gaze cue and motion cue) based on behavioral results and event-related potentials. Behavioral results revealed significant GCE in all conditions. In the schematic face group, the motion cue (two symmetrical dots shifting slightly to the side) induced a significantly smaller GCE than the dynamic gaze cues (two symmetrical dots moving within a rounded circle), while in the real face group, the motion cue (that is, the inverted-face gaze cue) remained a strong GCE compared with other conditions. With regard to the ERP results, we found the early directing attention negativity (EDAN), which was sensitive to voluntary cues (e.g. arrow cue) rather than gaze cue, in the schematic motion cue condition, but not in the inverted-face gaze cue condition. We supposed that the motion cue (real face) could activate the configural face processing even when the face is inverted. This finding supported that EDAN reflected a cue-triggered attention shift.

EEG Correlates of Preparatory Orienting, Contextual Updating, and Inhibition of Sensory Processing in Left Spatial Neglect

Studies with event-related potentials have highlighted deficits in the early phases of orienting to left visual targets in right-brain-damaged patients with left spatial neglect (N+). However, brain responses associated with preparatory orienting of attention, with target novelty and with the detection of a match/mismatch between expected and actual targets (contextual updating), have not been explored in N+. Here in a study in healthy humans and brain-damaged patients of both sexes we demonstrate that frontal activity that reflects supramodal mechanisms of attentional orienting (Anterior Directing Attention Negativity, ADAN) is entirely spared in N+. In contrast, posterior responses that mark the early phases of cued orienting (Early Directing Attention Negativity, EDAN) and the setting up of sensory facilitation over the visual cortex (Late Directing Attention Positivity, LDAP) are suppressed in N+. This uncoupling is associated with damage of parietal-frontal white matter. N+ also exhibit exaggerated novelty reaction to targets in the right side of space and reduced novelty reaction for those in the left side (P3a) together with impaired contextual updating (P3b) in the left space. Finally, we highlight a drop in the amplitude and latency of the P1 that over the left hemisphere signals the early blocking of sensory processing in the right space when targets occur in the left one: this identifies a new electrophysiological marker of the rightward attentional bias in N+. The heterogeneous effects and spatial biases produced by localized brain damage on the different phases of attentional processing indicate relevant functional independence among their underlying neural mechanisms and improve the understanding of the spatial neglect syndrome.SIGNIFICANCE STATEMENT Our investigation answers important questions: are the different components of preparatory orienting (EDAN, ADAN, LDAP) functionally independent in the healthy brain? Is preparatory orienting of attention spared in left spatial neglect? Does the sparing of preparatory orienting have an impact on deficits in reflexive orienting and in the assignment of behavioral relevance to the left space? We show that supramodal preparatory orienting in frontal areas is entirely spared in neglect patients though this does not counterbalance deficits in preparatory parietal-occipital activity, reflexive orienting, and contextual updating. This points at relevant functional dissociations among different components of attention and suggests that improving voluntary attention in N+ might be behaviorally ineffective unless associated with stimulations boosting the response of posterior parietal-occipital areas.

Endogenous Covert Spatial Orienting in Audition Cost-Benefit Analyses of Reaction Times and Event related Potentials

The present study examines mechanisms of endogenous covert spatial orienting in audition as revealed by event-related brain potentials (ERPs) and reaction times (RTs). In one experimental condition, subjects were instructed to respond to any target tone irrespective of whether it was presented in a valid (spatially predictive cue), neutral (uninformative cue), or invalid (misleading cue) trial. In another experimental condition, only target tones presented at a cued position required a response—that is, subjects could completely ignore tones presented at the uncued ear. Cue validity had an effect on RT, which consisted in benefits for valid trials and in costs for invalid trials relative to the RTs in neutral trials. There were also distinct ERP effects of cue validity in the 100–300 msec time range. These ERP effects were enlarged in the condition in which uncued tones could be ignored. The effects of cue validity on RTs and ERPs demonstrated covert orienting in audition both for stimuli requiring an overt response and also for stimuli that did not require a behavioural response. It is argued that this attentional selection is located at intermediate stages of information processing, rather than at peripheral stages such as basic sensory-specific processing or response selection.

Cortical and Subcortical Coordination of Visual Spatial Attention Revealed by Simultaneous EEG-fMRI Recording

Visual spatial attention has been studied in humans with both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) individually. However, due to the intrinsic limitations of each of these methods used alone, our understanding of the systems-level mechanisms underlying attentional control remains limited. Here, we examined trial-to-trial covariations of concurrently recorded EEG and fMRI in a cued visual spatial attention task in humans, which allowed delineation of both the generators and modulators of the cue-triggered event-related oscillatory brain activity underlying attentional control function. The fMRI activity in visual cortical regions contralateral to the cued direction of attention covaried positively with occipital gamma-band EEG, consistent with activation of cortical regions representing attended locations in space. In contrast, fMRI activity in ipsilateral visual cortical regions covaried inversely with occipital alpha-band oscillations, consistent with attention-related suppression of the irrelevant hemispace. Moreover, the pulvinar nucleus of the thalamus covaried with both of these spatially specific, attention-related, oscillatory EEG modulations. Because the pulvinar's neuroanatomical geometry makes it unlikely to be a direct generator of the scalp-recorded EEG, these covariational patterns appear to reflect the pulvinar's role as a regulatory control structure, sending spatially specific signals to modulate visual cortex excitability proactively. Together, these combined EEG/fMRI results illuminate the dynamically interacting cortical and subcortical processes underlying spatial attention, providing important insight not realizable using either method alone.SIGNIFICANCE STATEMENT Noninvasive recordings of changes in the brain's blood flow using functional magnetic resonance imaging and electrical activity using electroencephalography in humans have individually shown that shifting attention to a location in space produces spatially specific changes in visual cortex activity in anticipation of a stimulus. The mechanisms controlling these attention-related modulations of sensory cortex, however, are poorly understood. Here, we recorded these two complementary measures of brain activity simultaneously and examined their trial-to-trial covariations to gain insight into these attentional control mechanisms. This multi-methodological approach revealed the attention-related coordination of visual cortex modulation by the subcortical pulvinar nucleus of the thalamus while also disentangling the mechanisms underlying the attentional enhancement of relevant stimulus input and those underlying the concurrent suppression of irrelevant input.

Electrocorticography of Spatial Shifting and Attentional Selection in Human Superior Parietal Cortex

Spatial-attentional reorienting and selection between competing stimuli are two distinct attentional processes of clinical and fundamental relevance. In the past, reorienting has been mainly associated with inferior parietal cortex. In a patient with a subdural grid covering the upper and lower bank of the left anterior and middle intraparietal sulcus (IPS) and the superior parietal lobule (SPL), we examined the involvement of superior parietal cortex using a hybrid spatial cueing paradigm identical to that previously applied in stroke and in healthy controls. In SPL, as early as 164 ms following target onset, an invalidly compared to a validly cued target elicited a positive event-related potential (ERP) and an increase in intertrial coherence (ITC) in the theta band, regardless of the direction of attention. From around 400–650 ms, functional connectivity [weighted phase lag index (wPLI) analysis] between SPL and IPS briefly inverted such that SPL activity was driving IPS activity. In contrast, the presence of a competing distracter elicited a robust change mainly in IPS from 300 to 600 ms. Within superior parietal cortex reorienting of attention is associated with a distinct and early electrophysiological response in SPL while attentional selection is indexed by a relatively late electrophysiological response in the IPS. The long latency suggests a role of IPS in working memory or cognitive control rather than early selection.

Interrelation of attention and prediction in visual processing: Effects of task-relevance and stimulus probability

The potentially interactive influence of attention and prediction was investigated by measuring event-related potentials (ERPs) in a spatial cueing task with attention (task-relevant) and prediction (probabilistic) cues. We identified distinct processing stages of this interactive influence. Firstly, in line with the attentional gain hypothesis, a larger amplitude response of the contralateral N1, and Nd1 for attended gratings was observed. Secondly, conforming to the attenuation-by-prediction hypothesis, a smaller negativity in the time window directly following the peak of the N1 component for predicted compared to unpredicted gratings was observed. In line with the hypothesis that attention and prediction interface, unpredicted/unattended stimuli elicited a larger negativity at central-parietal sites, presumably reflecting an increased prediction error signal. Thirdly, larger P3 responses to unpredicted stimuli pointed to the updating of an internal model. Attention and prediction can be considered as differentiated mechanisms that may interact at different processing stages to optimise perception.

Changes in predictive cuing modulate the hemispheric distribution of the P1 inhibitory response to attentional targets

Brain activity related to orienting of attention with spatial cues and brain responses to attentional targets are influenced the probabilistic contingency between cues and targets. Compared to predictive cues, cues predicting at chance the location of targets reduce the filtering out of uncued locations and the costs in reorienting attention to targets presented at these locations. Slagter et al. (2016) have recently suggested that the larger target related P1 component that is found in the hemisphere ipsilateral to validly cued targets reflects stimulus-driven inhibition in the processing of the unstimulated side of space contralateral to the same hemisphere. Here we verified whether the strength of this inhibition and the amplitude of the corresponding P1 wave are modulated by the probabilistic link between cues and targets. Healthy participants performed a task of endogenous orienting once with predictive and once with non-predictive directional cues. In the non-predictive condition we observed a drop in the amplitude of the P1 ipsilateral to the target and in the costs of reorienting. No change in the inter-hemispheric latencies of the P1 was found between the two predictive conditions. The N1 facilitatory component was unaffected by predictive cuing. These results show that the predictive context modulates the strength of the inhibitory P1 response and that this modulation is not matched with changes in the inter-hemispheric interaction between the P1 generators of the two hemispheres.

How microsaccades relate to lateralized ERP components of spatial attention: A co-registration study

Covert shifts of attention that follow the presentation of a cue are associated with lateralized components in the event-related potential (ERP): the "early directing attention negativity" (EDAN) and the "anterior directing attention negativity" (ADAN). Traditionally, these shifts are thought to take place while gaze is fixated and, thus, in the absence of saccades. However, microsaccades of small amplitude (<1°) occur frequently and involuntarily also during fixation and are closely correlated with spatial attention. To investigate potential links between microsaccades and lateralized ERP components, we simultaneously recorded eye movements and ERPs in a spatial cueing task. As a first major result, we show that both the posterior EDAN and the orientation of microsaccades align more strongly with the location of the task-relevant part of the cue stimulus than with the direction of the attention shift indicated by that cue. A coupling between microsaccades and EDAN was also present on the single-trial level: The EDAN was largest when microsaccades were oriented toward the relevant cue, but absent when microsaccades were oriented away from it, suggesting that EDAN and microsaccades are generated by the same neural network, which selects relevant stimuli and orients behavior toward them. As a second major result, we show that small corneoretinal artifacts from microsaccades, which fall below conventional EOG rejection thresholds, contaminate the measurement of the ADAN. After correcting the EEG for microsaccade-related artifacts with an optimized variant of independent component analysis, ADAN was abolished at frontal sites, but a genuine ADAN was still present at central sites. Thus, the combined measurement of microsaccades and lateralized ERPs sheds new light onto cue-elicited shifts of covert attention.

Interplay between supramodal attentional control and capacity limits in the low-level visual processors modulate the tendency to inattention

When engaged in a demanding task, individuals may neglect unexpected visual stimuli presented concomitantly. Here we use a change detection task to show that propensity to inattention is associated with a flexible allocation of attentional resources to filter and represent visual information. This was reflected by N2 posterior contralateral (N2pc) and contralateral delay activity (CDA) respectively, but also during high-order reorienting of attentional resources (known as anterior directing attention negativity, ADAN). Results show that differences in noticing and failing to notice unexpected stimuli/changes are associated with different patterns of brain activity. When processing (N2) and working memory (CDA) capacities are low, resources are mostly allocated to small set-sizes and associated with a tendency to filter information during early low-level processing (N2). When resources are high, saturation is obtained with larger set-sizes. This is also associated to a tendency to select (N2) and reorient resources (ADAN) to maintain extra information (CDA).

Neuronal interactions in areas of spatial attention reflect avoidance of disgust, but orienting to danger

For survival, it is necessary to attend quickly towards dangerous objects, but to turn away from something that is disgusting. We tested whether fear and disgust sounds direct spatial attention differently. Using fMRI, a sound cue (disgust, fear or neutral) was presented to the left or right ear. The cue was followed by a visual target (a small arrow) which was located on the same (valid) or opposite (invalid) side as the cue. Participants were required to decide whether the arrow pointed up- or downwards while ignoring the sound cue. Behaviorally, responses were faster for invalid compared to valid targets when cued by disgust, whereas the opposite pattern was observed for targets after fearful and neutral sound cues. During target presentation, activity in the visual cortex and IPL increased for targets invalidly cued with disgust, but for targets validly cued with fear which indicated a general modulation of activation due to attention. For the TPJ, an interaction in the opposite direction was observed, consistent with its role in detecting targets at unattended positions and in relocating attention. As a whole our results indicate that a disgusting sound directs spatial attention away from its location, in contrast to fearful and neutral sounds.

Neural mechanisms of selective attention in the somatosensory system

Selective attention allows organisms to extract behaviorally relevant information while ignoring distracting stimuli that compete for the limited resources of their central nervous systems. Attention is highly flexible, and it can be harnessed to select information based on sensory modality, within-modality feature(s), spatial location, object identity, and/or temporal properties. In this review, we discuss the body of work devoted to understanding mechanisms of selective attention in the somatosensory system. In particular, we describe the effects of attention on tactile behavior and corresponding neural activity in somatosensory cortex. Our focus is on neural mechanisms that select tactile stimuli based on their location on the body (somatotopic-based attention) or their sensory feature (feature-based attention). We highlight parallels between selection mechanisms in touch and other sensory systems and discuss several putative neural coding schemes employed by cortical populations to signal the behavioral relevance of sensory inputs. Specifically, we contrast the advantages and disadvantages of using a gain vs. spike-spike correlation code for representing attended sensory stimuli. We favor a neural network model of tactile attention that is composed of frontal, parietal, and subcortical areas that controls somatosensory cells encoding the relevant stimulus features to enable preferential processing throughout the somatosensory hierarchy. Our review is based on data from noninvasive electrophysiological and imaging data in humans as well as single-unit recordings in nonhuman primates.

An Event-Related Potential Investigation of the Effects of Age on Alerting, Orienting, and Executive Function

The present study compared young and older adults on behavioral and neural correlates of three attentional networks (alerting, orienting, and executive control). Nineteen young and 16 older neurologically-healthy adults completed the Attention Network Test (ANT) while behavioral data (reaction time and error rates) and 64-channel event-related potentials (ERPs) were acquired. Significant age-related RT differences were observed across all three networks; however, after controlling for generalized slowing, only the alerting network remained significantly reduced in older compared with young adults. ERP data revealed that alerting cues led to enhanced posterior N1 responses for subsequent attentional targets in young adults, but this effect was weakened in older adults. As a result, it appears that older adults did not benefit fully from alerting cues, and their lack of subsequent attentional enhancements may compromise their ability to be as responsive and flexible as their younger counterparts. N1 alerting deficits were associated with several key neuropsychological tests of attention that were difficult for older adults. Orienting and executive attention networks were largely similar between groups. Taken together, older adults demonstrated behavioral and neural alterations in alerting, however, they appeared to compensate for this reduction, as they did not significantly differ in their abilities to use spatially informative cues to aid performance (e.g., orienting), or successfully resolve response conflict (e.g., executive control). These results have important implications for understanding the mechanisms of age-related changes in attentional networks.

Effect of working memory load on electrophysiological markers of visuospatial orienting in a spatial cueing task simulating a traffic situation

Visuospatial attentional orienting has typically been studied in abstract tasks with low ecological validity. However, real-life tasks such as driving require allocation of working memory (WM) resources to several subtasks over and above orienting in a complex sensory environment. The aims of this study were twofold: firstly, to establish whether electrophysiological signatures of attentional orienting commonly observed under simplified task conditions generalize to a more naturalistic task situation with realistic-looking stimuli, and, secondly, to assess how these signatures are affected by increased WM load under such conditions. Sixteen healthy participants performed a dual task consisting of a spatial cueing paradigm and a concurrent verbal memory task that simulated aspects of an actual traffic situation. Behaviorally, we observed a load-induced detriment of sensitivity to targets. In the EEG, we replicated orienting-related alpha lateralization, the lateralized ERPs ADAN, EDAN, and LDAP, and the P1-N1 attention effect. When WM load was high (i.e., WM resources were reduced), lateralization of oscillatory activity in the lower alpha band was delayed. In the ERPs, we found that ADAN was also delayed, while EDAN was absent. Later ERP correlates were unaffected by load. Our results show that the findings in highly controlled artificial tasks can be generalized to spatial orienting in ecologically more valid tasks, and further suggest that the initiation of spatial orienting is delayed when WM demands of an unrelated secondary task are high.

Event-related brain potentials during the visuomotor mental rotation task: The contingent negative variation scales to angle of rotation

Perceptual judgments about the angular disparity of a character from its standard upright (i.e., mental rotation task) result in a concurrent increase in reaction time (RT) and modulation of the amplitude of the P300 event-related brain potential (ERP). It has therefore been proposed that the P300 represents the neural processes associated with a visual rotation. In turn, the visuomotor mental rotation (VMR) task requires reaching to a location that deviates from a target by a predetermined angle. Although the VMR task exhibits a linear increase in RT with increasing oblique angles of rotation, work has not examined whether the task is supported via a visual rotation analogous to its mental rotation task counterpart. This represents a notable issue because seminal work involving non-human primates has ascribed VMR performance to the motor-related rotation of directionally tuned neurons in the primary motor cortex. Here we examined the concurrent behavioral and ERP characteristics of a standard reaching task and VMR tasks of 35°, 70°, and 105° of rotation. Results showed that the P300 amplitude was larger for the standard compared to each VMR task--an effect independent of the angle of rotation. In turn, the amplitude of the contingent negative variation (CNV)--an ERP related to cognitive and visuomotor integration for movement preparation--was systematically modulated with angle of rotation. Thus, we propose that the CNV represents an ERP correlate related to the cognitive and/or visuomotor transformation demands of increasing the angular separation between a stimulus and a movement goal.