HD-tDCS mitigates the executive vigilance decrement only under high cognitive demands.

Maintaining vigilance is essential for many everyday tasks, but over time, our ability to sustain it inevitably decreases, potentially entailing severe consequences. High-definition transcranial direct current stimulation (HD-tDCS) has proven to be useful for studying and improving vigilance. This study explores if/how cognitive load affects the mitigatory effects of HD-tDCS on the vigilance decrement. Participants (N = 120) completed a modified ANTI-Vea task (single or dual load) while receiving either sham or anodal HD-tDCS over the right posterior parietal cortex (rPPC). This data was compared with data from prior studies (N = 120), where participants completed the standard ANTI-Vea task (triple load task), combined with the same HD-tDCS protocol. Against our hypotheses, both the single and dual load conditions showed a significant executive vigilance (EV) decrement, which was not affected by the application of rPPC HD-tDCS. On the contrary, the most cognitively demanding task (triple task) showed the greatest EV decrement; importantly, it was also with the triple task that a significant mitigatory effect of the HD-tDCS intervention was observed. The present study contributes to a more nuanced understanding of the specific effects of HD-tDCS on the vigilance decrement considering cognitive demands. This can ultimately contribute to reconciling heterogeneous effects observed in past research and fine-tuning its future clinical application.

The ANTI-Vea-UGR Platform: A Free Online Resource to Measure Attentional Networks (Alertness, Orienting, and Executive Control) Functioning and Executive/Arousal Vigilance.

The Attentional Networks Test for Interactions and Vigilance-executive and arousal components (ANTI-Vea) is a computerized task of 32 min duration in the standard format. The task simultaneously assesses the main effects and interactions of the three attentional networks (i.e., phasic alertness, orienting, and executive control) and two dissociated components of vigilance with reasonable reliability (executive and arousal vigilance). We present this free and publicly accessible resource (ANTI-Vea-UGR; https://anti-vea.ugr.es/) developed to easily run, collect, and analyze data with the ANTI-Vea (or its subtasks measuring some attentional and/or vigilance components embedded in the ANTI-Vea). Available in six different languages, the platform allows for the adaptation of stimulus timing and procedure to facilitate data collection from different populations (e.g., clinical patients, children). Collected data can be freely downloaded and easily analyzed with the provided scripts and tools, including a Shiny app. We discuss previous evidence supporting that attention and vigilance components can be assessed in typical lab conditions as well as online and outside the laboratory. We hope this tutorial will help researchers interested in measuring attention and vigilance with a tool useful to collect data from large sample sizes and easy to use in applied contexts.

Event-related potentials associated with attentional networks evidence changes in executive and arousal vigilance.

Attention is regulated by three independent but interacting networks, that is, alerting, comprising phasic alertness and vigilance, orienting, and executive control. Previous studies analyzing event-related potentials (ERPs) associated with attentional networks have focused on phasic alertness, orienting, and executive control, without an independent measure of vigilance. ERPs associated with vigilance have been instead measured in separate studies and via different tasks. The present study aimed to differentiate ERPs associated with attentional networks by simultaneously measuring vigilance along with phasic alertness, orienting, and executive control. Forty participants (34 women, age: M = 25.96; SD = 4.96) completed two sessions wherein the electroencephalogram was recorded while they completed the Attentional Networks Test for Interactions and Vigilance-executive and arousal components, a task that measures phasic alertness, orienting, and executive control along with executive (i.e., detection of infrequent critical signals) and arousal (i.e., sustaining a fast reaction to environmental stimuli) vigilance. ERPs previously associated with attentional networks were replicated here: (a) N1, P2, and contingent negative variation for phasic alertness; (b) P1, N1, and P3 for orienting; and (c) N2 and slow positivity for executive control. Importantly, different ERPs were associated with vigilance: while the executive vigilance decrement was associated with an increase in P3 and slow positivity across time-on-task, arousal vigilance loss was associated with reduced N1 and P2 amplitude. The present study shows that attentional networks can be described by different ERPs simultaneously observed in a single session, including independent measures of executive and arousal vigilance on its assessment.

The mitigation of the executive vigilance decrement via HD-tDCS over the right posterior parietal cortex and its association with neural oscillations.

Vigilance-maintaining a prolonged state of preparation to detect and respond to specific yet unpredictable environmental changes-usually decreases across prolonged tasks, causing potentially severe real-life consequences, which could be mitigated through transcranial direct current stimulation (tDCS). The present study aimed at replicating previous mitigatory effects observed with anodal high-definition tDCS (HD-tDCS) over the right posterior parietal cortex (rPPC) while extending the analyses on electrophysiological measures associated with vigilance. In sum, 60 participants completed the ANTI-Vea task while receiving anodal (1.5 mA, n = 30) or sham (0 mA, n = 30) HD-tDCS over the rPPC for ~ 28 min. EEG recordings were completed before and after stimulation. Anodal HD-tDCS specifically mitigated executive vigilance (EV) and reduced the alpha power increment across time-on-task while increasing the gamma power increment. To further account for the observed behavioral and physiological outcomes, a new index of Alphaparietal/Gammafrontal is proposed. Interestingly, the increment of this Alphaparietal/Gammafrontal Index with time-on-task is associated with a steeper EV decrement in the sham group, which was mitigated by anodal HD-tDCS. We highlight the relevance of replicating mitigatory effects of tDCS and the need to integrate conventional and novel physiological measures to account for how anodal HD-tDCS can be used to modulate cognitive performance.

Changes in Response Criterion and Lapse Rate as General Mechanisms of Vigilance Decrement: Commentary on McCarley and Yamani (2021).

Multiple theories have used perceptual sensitivity and response criterion indices to explain the decrements in performance across time on task (i.e., vigilance decrement). In a recent study, McCarley and Yamani (2021) offered conceptual and methodological advances to this debate by using a vigilance task that parametrically manipulates noise and signal and analyzes the outcomes with psychometric curves. In the present Commentary, we reanalyze data (N = 553) from a different, already existing vigilance task, the Attentional Networks Test for Interactions and Vigilance-executive and arousal components (ANTI-Vea). Psychometric curves with the ANTI-Vea showed robust changes in response criterion and lapse rate, although not in sensitivity. Our interpretation is that the need to keep the standard in memory in McCarley and Yamani's task could produce a decrease in sensitivity and be related to reduced fidelity of the memory representation rather than to a decrement in perceptual abilities across time on task.

Gaze elicits social and nonsocial attentional orienting: An interplay of shared and unique conflict processing mechanisms.

Subtle to no attentional differences have been broadly observed when using gaze and arrows as orienting cues. However, recent studies have found opposite effects when they are used as targets in spatial interference tasks, with arrows eliciting faster responses when their position is congruent with the indicated direction and gaze producing faster responses in incongruent conditions. In two preregistered experiments aimed at exploring the mechanisms supporting these findings, we examined whether the congruency sequence effects (CSE) elicited by gaze and arrows generalized from one stimulus to another, using an intrablock design where the type of stimuli was manipulated on a trial-by-trial basis. Typical CSE were observed for arrows, with a decrease of congruency effects after incongruent trials, and reversed CSE for gaze, with an increased inversion of congruency effects after incongruent trials. Both patterns occurred independently of the preceding type of target, showing that congruency effects can decrease after positive outcomes (e.g., arrow trials following an incongruent gaze trial), and generalized across different nonsocial and social stimuli as shown in a third experiment. These results are consistent with the coexistence of a shared spatial interference component between gaze and arrow trials, potentially responsible for the CSE obtained in switching target trials, and an additional social dimension, exclusively engaged in gaze trials. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

A vigilance decrement comes along with an executive control decrement: Testing the resource-control theory.

A decrease in vigilance over time is often observed when performing prolonged tasks, a phenomenon known as "vigilance decrement." The present study aimed at testing some of the critical predictions of the resource-control theory about the vigilance decrement. Specifically, the theory predicts that the vigilance decrement is mainly due to a drop in executive control, which fails to keep attentional resources on the external task, thus devoting a larger number of resources to mind-wandering across time-on-task. Datasets gathered from a large sample size (N = 617) who completed the Attentional Networks Test for Interactions and Vigilance-executive and arousal components in Luna, Roca, Martín-Arévalo, and Lupiáñez (2021b, Behavior Research Methods, 53[3], 1124-1147) were reanalyzed to test whether executive control decreases across time in a vigilance task and whether the vigilance decrement comes along with the decrement in executive control. Vigilance was examined as two dissociated components: executive vigilance, as the ability to detect infrequent critical signals, and arousal vigilance, as the maintenance of a fast reaction to stimuli. The executive control decrement was evidenced by a linear increase in the interference effect for mean reaction time, errors, and the inverse efficiency score. Critically, interindividual differences showed that the decrease in the executive-but not in the arousal-component of vigilance was modulated by the change in executive control across time-on-task, thus supporting the predictions of the resource-control theory. Nevertheless, given the small effect sizes observed in our large sample size, the present outcomes suggest further consideration of the role of executive control in resource-control theory.

Cognitive load mitigates the executive but not the arousal vigilance decrement.

Previous research has shown opposite effects of dual tasking on the vigilance decrement phenomenon. We examined the executive (i.e., detecting infrequent critical signals) and arousal (i.e., sustaining a fast reaction to stimuli without much control on responses) vigilance decrements as a function of task load. Ninety-six participants performed either a single signal-detection (i.e., executive vigilance) task, a single reaction time (i.e., arousal vigilance) task, or a dual vigilance task with the same stimuli and procedure. All participants self-reported their fatigue' state along the session. Exploratory analyses included data from a previous study with a triple task condition. Task load significantly modulated the executive but not the arousal vigilance decrement. Interestingly, the largest increase in mental fatigue was observed in the single executive vigilance task condition. We discuss limitations of classic vigilance theories to account for the vigilance decrement and changes in mental fatigue as a function of task load.

Attentional Capture From Inside vs. Outside the Attentional Focus.

In this study, we jointly reported in an empirical and a theoretical way, for the first time, two main theories: Lavie's perceptual load theory and Gaspelin et al.'s attentional dwelling hypothesis. These theories explain in different ways the modulation of the perceptual load/task difficulty over attentional capture by irrelevant distractors and lead to the observation of the opposite results with similar manipulations. We hypothesized that these opposite results may critically depend on the distractor type used by the two experimental procedures (i.e., distractors inside vs. outside the attentional focus, which could be, respectively, considered as potentially relevant vs. completely irrelevant to the main task). Across a series of experiments, we compared both theories within the same paradigm by manipulating both the perceptual load/task difficulty and the distractor type. The results were strongly consistent, suggesting that the influence of task demands on attentional capture varies as a function of the distractor type: while the interference from (relevant) distractors presented inside the attentional focus was consistently higher for high vs. low load conditions, there was no modulation by (irrelevant) distractors presented outside the attentional focus. Moreover, we critically analyzed the theoretical conceptualization of interference using both theories, disentangling important outcomes for the dwelling hypothesis. Our results provide specific insights into new aspects of attentional capture, which can critically redefine these two predominant theories.

The causal role of DLPFC top-down control on the acquisition and the automatic expression of implicit learning: State of the art.

Implicit learning refers to the incidental acquisition and expression of knowledge that is not accompanied by full awareness of its contents. Implicit sequence learning (ISL) represents one of the most useful paradigms to investigate these processes. In this paradigm, participants are usually instructed to respond to the location of a target that moves regularly through a set of possible locations. Although participants are not informed about the existence of a sequence, they eventually learn it implicitly, as attested by the costs observed when this sequence is violated in a reduced set of control trials. Interestingly, the expression of this learning decreases immediately after a control trial, in a way that resembles the adjustments triggered in response to incongruent trials in interference tasks. These effects have been attributed to a control network involving dorsolateral prefrontal cortex (DLPFC) and cingulate (ACC) structures. In the present work, we reviewed a group of recent studies which had inhibited DLPFC top-down control by means of non-invasive brain stimulation to increase the acquisition of ISL. In addition, as no previous study has investigated the effect of inhibiting top-down control on releasing the automatic expression of ISL, we present a pre-registered - yet exploratory - study in which an inhibitory continuous theta burst stimulation protocol was applied over an anterior-ventral portion of the dorsolateral prefrontal cortex (DLPFC) highly interconnected with the ACC, and whose activity has been specifically linked to motor control (i.e., Right DLPFC, n = 10 or the Left DLPFC, n = 10), compared to active Vertex stimulation (n = 10). Contrary to our hypotheses, the results did not show evidence for the involvement of such region in the expression of ISL. We discussed the results in the context of the set of contradictory findings reported in the systematic review.

Transcranial Magnetic Stimulation of the Right Superior Parietal Lobule Modulates the Retro-Cue Benefit in Visual Short-Term Memory.

Several studies have shown enhanced performance in change detection tasks when spatial cues indicating the probe's location are presented after the memory array has disappeared (i.e., retro-cues) compared with spatial cues that are presented simultaneously with the test array (i.e., post-cues). This retro-cue benefit led some authors to propose the existence of two different stores of visual short-term memory: a weak but high-capacity store (fragile memory (FM)) linked to the effect of retro-cues and a robust but low-capacity store (working memory (WM)) linked to the effect of post-cues. The former is thought to be an attention-free system, whereas the latter would strictly depend on selective attention. Nonetheless, this dissociation is under debate, and several authors do not consider retro-cues as a proxy to measure the existence of an independent memory system (e.g., FM). We approached this controversial issue by altering the attention-related functions in the right superior parietal lobule (SPL) by transcranial magnetic stimulation (TMS), whose effects were mediated by the integrity of the right superior longitudinal fasciculus (SLF). Specifically, we asked whether TMS on the SPL affected the performance of retro cues vs. post-cues to a similar extent. The results showed that TMS on the SPL, mediated by right SLF-III integrity, produced a modulation of the retro-cue benefit, namely a memory capacity decrease in the post-cues but not in the retro-cues. These findings have strong implications for the debate on the existence of independent stages of visual short-term memory and for the growing literature showing a key role of the SLF for explaining the variability of TMS effects across participants.

Attentional networks functioning and vigilance in expert musicians and non-musicians.

Previous literature has shown cognitive improvements related to musical training. Attention is one cognitive aspect in which musicians exhibit improvements compared to non-musicians. However, previous studies show inconsistent results regarding certain attentional processes, suggesting that benefits associated with musical training appear only in some processes. The present study aimed to investigate the attentional and vigilance abilities in expert musicians with a fine-grained measure: the ANTI-Vea (ANT for Interactions and Vigilance-executive and arousal components; Luna et al. in J Neurosci Methods 306:77-87, https://doi.org/10.1016/j.jneumeth.2018.05.011 , 2018). This task allows measuring the functioning of the three Posner and Petersen's networks (alerting, orienting, and executive control) along with two different components of vigilance (executive and arousal vigilance). Using propensity-score matching, 49 adult musicians (18-35 years old) were matched in an extensive set of confounding variables with a control group of 49 non-musicians. Musicians showed advantages in processing speed and in the two components of vigilance, with some specific aspects of musicianship such as years of practice or years of lessons correlating with these measures. Although these results should be taken with caution, given its correlational nature, one possible explanation is that musical training can specifically enhance some aspects of attention. Nevertheless, our correlational design does not allow us to rule out other possibilities such as the presence of cognitive differences prior to the onset of training. Moreover, the advantages were observed in an extra-musical context, which suggests that musical training could transfer its benefits to cognitive processes loosely related to musical skills. The absence of effects in executive control, frequently reported in previous literature, is discussed based on our extensive control of confounds.

Measuring attention and vigilance in the laboratory vs. online: The split-half reliability of the ANTI-Vea.

Over the past few years, there has been growing interest in using online methods for collecting data from large samples. However, only a few studies have administered online behavioral tasks to assess attention outside the lab. In the present study, we assessed the classic attentional functions and two vigilance components using two versions of the Attentional Networks Test for Interactions and Vigilance-executive and arousal vigilance components (ANTI-Vea): (1) a standard version, performed under typical experimental conditions (n = 314), and (2) an online version, completed outside the lab (n = 303). Both versions were equally effective in assessing (1) the main effects and interactions of phasic alertness, orienting, and executive control, and (2) the executive (i.e., a decline in the ability to detect infrequent critical signals) and the arousal (i.e., a progressive slowness and variability in responses to stimuli from the environment) vigilance decrement across time on task. Responses were generally slower in the online than in the standard version. Importantly, the split-half reliability observed for both tasks was (1) higher for executive control (~.67) than for phasic alertness and orienting (< .40), as observed in previous versions of the task, and (2) between .71 and .99 for the executive and arousal vigilance measures. We expect the present study will be of interest to researchers aiming to assess attentional functions with a valid and reliable method that, importantly, is publicly available on an open website ( https://www.ugr.es/~neurocog/ANTI/ ) and is easy to use in applied contexts.

On the putative role of intervening events in exogenous attention.

In exogenous attention, two main behavioural effects are usually observed across time: facilitation at short cue-target onset asynchronies (CTOAs), and Inhibition of Return (IOR) at longer CTOAs. The presentation of an intervening event (IE)-i.e., a cue presented at fixation between the peripheral cue and target period-favours the appearance of IOR. However, although there is a general consensus on this empirical modulation, there is no agreement about the putative role of IEs and/or the mechanism/s underlying their effect. While some authors consider IEs as a "cue-back", automatically reorienting attention to fixation, thus allowing IOR to occur, others have considered IEs as events modulating cue-target integration processes, consequently affecting exogenous cueing. Even in this later case, it is not clear whether IEs modulate cueing by inducing an attentional set (top-down) modulation or by inducing a trial-by-trial (bottom-up) online modulation. To disentangle this issue, in two experiments, we manipulated the proportion of trials in which the IE was presented, thus being able to measure the effect of the presence/absence and proportion of IEs. We observed a gradual influence of the % of IEs over cueing effects, which becomes less positive or more negative as the % of IEs increases. This pattern of findings fits well with the idea that facilitation and IOR depend on cue-target integration processes, and presents critical implications for the open debate about the mechanism/s underlying exogenous spatial cueing effects.

Microstructural white matter connectivity underlying the attentional networks system.

Nowadays, there is considerable controversy regarding the structural connectivity underlying the attentional networks system (i.e., alerting and vigilance, orienting, and executive control). The present study aimed at further examining and dissociating the white matter connectivity underlying attentional and vigilance functioning by overcoming some critical limitations in previous research. To this end, we performed virtual in vivo dissections of attention-related white matter tracts from thirty healthy adults. Participants completed two sessions of the Attentional Networks Test for Interactions and Vigilance, a suitable task to assess simultaneously phasic alertness, orienting, executive control, and the executive component of vigilance (i.e., the ability to detect infrequent critical signals). Whereas we found a consistent correlation between phasic alertness and both the right dorsolateral prefrontal caudate tract and the splenium of the corpus callosum, evidence obtained for white matter connectivity underlying orienting, executive control, and executive vigilance, was either weak at the best, inconsistent, or null. White matter connectivity seemed to support nevertheless the most reliable performance: overall reaction time for attentional functioning was significantly associated with the left cingulate fasciculus and overall reaction time for executive vigilance was significantly linked to the bilateral superior longitudinal fasciculus I. The present outcomes provide interesting, consistent, and reliable evidence concerning the structural connectivity underlying the alerting network. We still consider that further evidence is necessary to better understand the controversial relationship between attentional/vigilance processes and microstructural white matter connectivity though.

Reduction of emotional distraction during target processing by attentional manipulations.

Previous research has demonstrated that fully irrelevant distractors - i.e., not sharing any feature with the target - capture our attention and modulate our responses. In the present study, we explored this interference by irrelevant distractors in a series of three experiments wherein the emotional valence of distractors (negative vs. neutral valence) was manipulated along with endogenous and exogenous attention. We aimed at jointly investigating - within the same paradigm - the possible modulations over the interference effect by these three critical variables in a systematic way. Although we replicated the interference effect by distractors previously reported in Martín-Arévalo et al. (2015), results showed no attentional and only weak emotional valence modulations over the interference effect. We discuss the possible boundary conditions underlying the absence (or weakness) of modulations over the interference effect by distractors observed in our experiments.

A High-Definition tDCS and EEG study on attention and vigilance: Brain stimulation mitigates the executive but not the arousal vigilance decrement.

Attention comprises a wide set of processes such as phasic alertness, orienting, executive control, and the executive (i.e., detecting infrequent targets) and arousal (i.e., sustaining a fast reaction) vigilance components. Importantly, the effects of transcranial direct current stimulation (tDCS) over attentional functioning have been mostly addressed by measuring these processes separately and by delivering offline tDCS with low precision over the stimulation region. In the current study, we examined the effects of online High-Definition tDCS (HD-tDCS) over the behavioral and electrophysiological functioning of attentional and vigilance components. Participants (N = 92) were randomly assigned to one of three stimulation groups: right dorsolateral prefrontal cortex stimulation, right posterior parietal cortex (PPC) stimulation, and sham. All of them performed - in combination with the HD-tDCS protocol - an attentional networks task (ANTI-Vea) suitable to measure the executive and arousal components of vigilance along with three typical attentional functions: phasic alertness, orienting, and executive control. In addition, EEG was registered at the baseline and at the post-stimulation period. We observed that, regardless the stimulation region, online HD-tDCS: (a) reduced phasic alertness (p = .008), but did not modulated the orienting and executive control functioning; and (b) mitigated the executive vigilance decrement (p = .011), but did not modulated arousal vigilance across time-on-task. Interestingly, only HD-tDCS over PPC reduced considerably the increment of alpha power observed across time-on-task (p = .009). The current study provides further evidence for both an empirical dissociation between vigilance components and the cortical regions underlying attentional processes. We highlight the advantages of using online HD-tDCS to examine the stimulation effects on attentional and vigilance functioning.

On the time course of spatial cueing: Dissociating between a set for fast reorienting and a set for cue-target segregation.

The present study tests whether two different manipulations leading to an earlier appearance of Inhibition of Return might operate by setting the system in different ways. Whereas the use of a range of very long SOAs has been proposed to set the system for an early reorienting of attention (Cheal & Chastain, 2002), introducing a distractor at the location opposite the target seems to induce a set to represent the cue and the target as separated events instead of the same event (Lupiáñez et al., 1999, 2001). The effects of these two manipulations were directly compared by using a spatial stroop paradigm. Although both manipulations altered the time course of cueing effects, we report here a pattern of critical dissociations: (i) the distractor manipulation was unique in introducing a shift towards more negative cueing affecting generally all levels of SOA, including the shortest 100 ms SOA; and (ii) the distractor manipulation, but not the range of SOAs, was also able to prevent the expected interaction between spatial stroop effects and cueing effects at the shortest SOA, typically found in previous experiments in the absence of a distractor (Funes et al., 2003). This pattern of dissociations is well accommodated into the hypothesis that these two attentional sets are different in nature.

Does spatial attention modulate sensory memory?

According to some theoretical models, information contained in visual short-term memory (VSTM) consists of two main memory stages/storages: sensory memory, a system wherein information is stored for a brief time with high detail and low resistance to visual interference, and visual working memory, a low-capacity system wherein information is protected from visual interference and maintained for longer delays. Previous studies have consistently shown a strong relationship between attention and visual working memory. However, evidence is contradictory on whether or not attention modulates the construction and maintenance of visual representations in sensory memory. Here, we examined whether and how spatial attention differentially affects sensory and working memory contents, by separately analysing attentional costs and attentional benefits. Results showed that both sensory memory and visual working memory were reliably affected by the distribution of spatial attention, suggesting that spatial attention modulates the VSTM content starting from very early stages of memory storage. Moreover, endogenously attending a specific location led to similar performance in sensory and working memory, and therefore to larger attentional benefits in working memory (where there was more room for improvement than in sensory memory, because of worse performance in unattended locations). On the other hand, exogenous attentional capture by peripheral unpredictive cues produced invariant attentional costs and invariant attentional benefits regardless of the memory type, with performance being higher in sensory memory than in working memory even at the attended location.