Mind Wandering and Task-Focused Attention: ERP Correlates

Electrophysiological correlation between executive vigilance and attention network based on cognitive resource control theory

Attention is comprised of three independent and interacting attention networks: phasic alertness, orienting, and executive control. Previous studies have explored event-related potentials associated with these attention networks and executive vigilance, there is a lack of research on the relationship between executive vigilance and the three attention networks. However, there is a lack of research on the relationship between executive vigilance and the three attention networks. The present study aims to investigate this relationship. Based on the theory of cognitive resource control, two experimental blocks were designed with the vigilance task as the control variable. A total of 39 participants completed both ANTI and ANTI-V trials (two variants of the traditional attention network test ANT) in the same period. Through analysis of behavior measures (RT) and electrophysiological results related to phasic alertness (N1, P2, and contingent negative variation), orienting (P1, N1, and P3), and executive control (N2 and slow positive potential), we found that the reaction time of the ANTI block was lower than that of the ANTI-V block under all conditions, This suggests that adding a vigilance task may lead to reduced allocation of attention resources across all three attention networks. Furthermore, the orienting ability was weaker in the ANTI-V experimental block compared to that in the ANTI block due to effects on P1 and P3 regulation by the vigilance task. The N2 amplitude of the ANTI-V block was consistently reduced under similar conditions, indicating a weakening of executive control ability. The electrophysiological results revealed that executive vigilance inhibited the component of early attention perception related to the orienting network and was also related to the ability to detect conflict in the executive control network.

The experimental study of consciousness: Is psychology travelling back to the future?

It was with the promise of rendering an experimental approach to consciousness that psychology started its trajectory as an independent science more than 150 years ago. Here, we will posit that the neurosciences were instrumental in leading psychology to resume the study of consciousness by projecting an empirical agenda for the future. First, we will start by showing how scientists were able to venture into the consciousness of supposedly unconscious patients, opening the door for the identification of important neural correlates of distinct consciousness states. Then, we will describe how different technological advances and elegant experimental paradigms helped in establishing important neuronal correlates of global consciousness (i.e., being conscious at all), perceptual consciousness (i.e., being conscious of something), and self-consciousness (i.e., being conscious of itself). Finally, we will illustrate how the study of complex consciousness experiences may contribute to the clarification of the mechanisms associated with global consciousness, the relationship between perceptual and self-consciousness, and the interface among distinct self-consciousness domains. In closing, we will elaborate on the road ahead of us for re-establishing psychology as a science of consciousness.

Bayesian interpretation of the prefrontal P2 ERP component based on stimulus/response mapping uncertainty

The brain can be seen as a predictive system continuously computing prior information to guess posterior probabilities minimizing sources of uncertainty. To test this Bayesian view of the brain, event-related potentials (ERP) methods have been used focusing on the well-known P3 component, traditionally associated with decision-making processes and sources of uncertainty regarding target probability. Another ERP component linked with decision-making is the prefrontal P2 (pP2) component, which has never been considered within the Bayesian framework. To test which source of uncertainty could be associated with the pP2, uncertainty induced by target probability and stimulus-response (S/R) mapping were modulated in three visuomotor tasks. Results showed that the pP2 had the largest amplitude in the task with the largest uncertainty regarding the S/R mapping and degraded as the S/R mapping became more predictable. The P3 was maximal in the tasks with larger uncertainty regarding the target probability. While we confirmed the P3 association with target probability, we extended our knowledge on the pP2 associating it with S/R mapping uncertainty. This component, which has been previously localized within the anterior insular cortex, may minimize S/R mapping uncertainty allowing response-related evidence accumulation and comparing current events with internal representations to extract action-related probabilities.

Breathing Right… or Left! The Effects of Unilateral Nostril Breathing on Psychological and Cognitive Wellbeing: A Pilot Study

The impact of controlled breathing on cognitive and affective processing has been recognized since ancient times, giving rise to multiple practices aimed at achieving different psychophysical states, mostly related to mental clarity and focus, stress reduction, and relaxation. Previous scientific research explored the effects of forced unilateral nostril breathing (UNB) on brain activity and emotional and cognitive functions. Some evidence concluded that it had a contralateral effect, while other studies presented controversial results, making it difficult to come to an unambiguous interpretation. Also, a few studies specifically addressed wellbeing. In the present study, we invited a pilot sample of 20 participants to take part in an 8-day training program for breathing, and each person was assigned to either a unilateral right nostril (URNB) or left nostril breathing condition (ULNB). Then, each day, we assessed the participants' wellbeing indices using their moods and mind wandering scales. The results revealed that, after the daily practice, both groups reported improved wellbeing perception. However, the effect was specifically related to the nostril involved. URNB produced more benefits in terms of stress reduction and relaxation, while ULNB significantly and increasingly reduced mind-wandering occurrences over time. Our results suggest that UNB can be effectively used to increase wellbeing in the general population. Additionally, they support the idea that understanding the effects of unilateral breathing on wellbeing and cognition requires a complex interpretive model with multiple brain networks to address bottom-up and top-down processes.

Visual perceptual processing is unaffected by cognitive fatigue

Cognitive fatigue (CF) can lead to an increase in the latency of simple reaction time, although the processes involved in this delay are unknown. One potential explanation is that a longer time may be required for sensory processing of relevant stimuli. To investigate this possibility, the current study used a visual inspection time task to measure perceptual processing speed before and after a CF (math and memory) or non-fatiguing (documentary film) intervention. Subjective fatigue and simple reaction time significantly increased following the CF, but not the non-fatiguing intervention, confirming that CF was induced. Conversely, there was no effect of CF on inspection time task performance. It was therefore concluded that the speed of perceptual processing is not significantly impacted by CF, and thus is unlikely to underlie CF-related reaction time increases. Instead, increases in simple reaction time latency in CF may be due to delays in response preparation or initiation.

The effect and efficiency of attentional networks and the brain electrophysiology

The attention networks test (ANT) is frequently utilized to evaluate executive, alerting, and orienting attentional components. Additionally, it serves as an activation task in neuroimaging studies. This study aimed to examine the relationship between attention networks and brain electrophysiology. The study enrolled 40 right-handed male students (age = 20.8 ± 1.3 years) who underwent the revised attention network test, while their electroencephalogram signals were recorded. The study aimed to explore the effects of attention networks and their efficiencies on brain electrophysiology. The results indicated that the P3 amplitude was modulated by the conflict effect in the central (p-value = 0.014) and parietal (p-value = 0.002) regions. The orienting component significantly influenced P1 and N1 latencies in the parietal and parieto-occipital regions (p-values < 0.006), as well as P1 and N1 amplitude in the parieto-occipital region (p-values = 0.017 and 0.011). The alerting component significantly affected P1 latency and amplitude in the parietal and parieto-occipital regions, respectively (p-value = 0.02). Furthermore, N1 amplitude and the time interval between P1 and N1 were significantly correlated with the efficiency of alerting and orienting networks. In terms of connectivity, the coherence of theta and alpha bands significantly decreased in the incongruent condition compared to the congruent condition. Additionally, the effects of attention networks on event-related spectral perturbation were observed. The study revealed the influence of attention networks on various aspects of brain electrophysiology. Specifically, the alerting score correlated with the amplitude of the N1 component in the double-cue and no-cue conditions in the parieto-occipital region, while the orienting score in the same region correlated with the N1 amplitude in the valid cue condition and the difference in N1 amplitude between the valid cue and double-cue conditions. Overall, empirical evidence suggests that attention networks not only impact the amplitudes of electrophysiological activities but also influence their time course.

The effect of background sounds on mind wandering

Mind wandering (MW) reflects a situation in which the cognitive system is detached from the main task and involved with inner thoughts. It has been well document that music and other background sounds can have positive effects on number of cognitive functioning. In addition, other body of literature suggests that background sounds might have specifically positive effect on individuals with more attention deficiencies. Hence, the current study examines the effect of background sounds on MW. In two experiments, the effect of background sounds: music (Experiment 1) or an alerting tone (Experiment 2) while performing sustained attention tasks was examined among typical development participants with different severity of attention deficiency. Background sounds were found to reduce MW especially in individuals with more ADHD symptoms. This was further discussed in the context of several theories, and it was suggested that background sound might be used as a tool for MW reduction.

Anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex improves attentional control in chronically stressed adults

Introduction

Chronic stress is a long-term condition that negatively affects cognitive ability and mental health. Individuals who experience chronic stress show poor attentional control. Transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) modulates executive function domains. Therefore, it is beneficial to investigate whether tDCS of the DLPFC could improve attentional control and relieve stress in chronically stressed individuals.

Methods

We assess the event-related potentials (ERPs) associated with attentional control in individuals with chronic stress after the tDCS intervention. Forty individuals were randomly assigned to either the anodal tDCS group, which received 5 sessions of the 20 min tDCS over the DLPFC (2 mA; n = 20), or the sham tDCS (n = 20). Participants' stress levels, anxiety, depressive symptoms, and state affects were assessed and compared before and after the intervention. The ERP was collected through electroencephalography (EEG) technology during an attentional network test.

Results

After the anodal tDCS, we found a significant decrease in the perceived stress scale (PSS) scores (from an average score of 35.05 to 27.75), p = 0.01 as well as the State-Trait Anxiety Inventory (STAI) scores, p = 0.002. Better performance in the attentional network test, a significant reduction in the N2 amplitudes, and an enhancement in the P3 amplitudes (both cues and targets) were also found in the anodal tDCS group.

Discussion

Our study findings suggest that tDCS to the left DLPFC could effectively relieve chronic stress, potentially reflected by increased attentional control.

The Interaction of the Dorsolateral and Ventromedial Prefrontal Cortex During Mind Wandering

BACKGROUND AND AIMS

Mind wandering refers to spontaneously occurring, often disruptive thoughts during an ongoing task or resting state. The ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are two main cortical areas which are involved in this process. This study aimed to explore the interaction of these areas during mind wandering by enhancing specific oscillatory activity of these areas via transcranial alternating current stimulation (tACS) in the theta frequency range.

MATERIAL AND METHODS

Eighteen healthy adults participated in a randomized, single-blinded, crossover study. tACS (1.5 mA, 6 Hz) was applied in five sessions with one week interval via (1) two channels with synchronized stimulation over the left dlPFC and right vmPFC, (2) the same electrode placement with anti-phase stimulation, (3) stimulation over the left dlPFC only, (4) stimulation over right vmPFC only, and (5) sham stimulation. The return electrodes were placed over the contralateral shoulder in all conditions. The sustained attention to response task (SART) with embedded probes about task-unrelated-thoughts and awareness of these thoughts was performed during intervention.

RESULTS

Stimulation did not alter SART performance. Right vmPFC stimulation decreased mind wandering and increased awareness of mind wandering. Left dlPFC stimulation and desynchronized stimulation over the dlPFC and vmPFC increased mind wandering compared to the sham stimulation condition. Synchronized stimulation had no effect on mind wandering, but increased awareness of mind wandering.

CONCLUSION

The results suggest that regional entrainment of the vmPFC decreases mind wandering and increases awareness of mind wandering, whereas regional entrainment of the dlPFC increases mind wandering, but decreases awareness. Under desynchronized stimulation of both areas, the propensity of mind wandering was increased, whereas synchronized stimulation increased the awareness of mind wandering. These results suggest a role of the dlPFC in initiation of mind wandering, whereas the vmPFC downregulates mind wandering, and might exert this function by counteracting respective dlPFC effects via theta oscillations.

Vigilance End-Spurt Patterns in Event-Related Potentials

The end-spurt effect, where performance declines with time-on-task and then increases toward the end of a task, has garnered little attention in the vigilance literature. Researchers have suggested the performance enhancement is due to increased motivation or arousal with knowledge of the end of the vigil. However, recent examination of neural signature patterns during a simultaneous discrimination task, where task length was unknown, provided preliminary support that the end-spurt reflects pacing of resources. The current effort expands this previous work to an additional simultaneous task and to a successive discrimination task across two sessions, one where task length was not known and one where task length was known. Twenty-eight (Study 1) and a separate 24 (Study 2) participants completed a Simultaneous Radar task (Study 1) in one session and Simultaneous and Successive Lines tasks (Study 2) across two sessions while neural data was collected. Several event-related potentials exhibited non-monotonic patterns during the vigilance tasks, in some cases reflecting end-spurt patterns, but more commonly reflecting higher-order polynomial patterns. These patterns were more prevalent in anterior regions as opposed to posterior regions. Of note, the N1 anterior exhibited consistent general patterns across all the vigilance tasks and across sessions. Importantly, even when participants had knowledge of session length, some ERPs still exhibited higher-order polynomial trends, suggesting pacing rather than an end-spurt from motivation or arousal as the vigil ends. These insights can help inform predictive modeling of vigilance performance and the implementation of mitigation efforts to allay the vigilance decrement.

Electrophysiological Correlates of Different Proactive Controls during Response Competition and Inhibition Tasks

The present study aims to investigate the behavioral outcomes and the antecedent brain dynamics during the preparation of tasks in which the discrimination is either about the choice (choice response task; CRT) or the action (Go/No-go), and in a task not requiring discrimination (simple response task; SRT). Using event-related potentials (ERPs), the mean amplitude over prefrontal, central, and parietal-occipital sites was analyzed in 20 young healthy participants in a time frame before stimulus presentation to assess cognitive, motor, and visual readiness, respectively. Behaviorally, participants were faster and more accurate in the SRT than in the CRT and the Go/No-go. At the electrophysiological level, the proactive cognitive and motor ERP components were larger in the CRT and the Go/No-go than the SRT, but the largest amplitude emerged in the Go/No-go. Further, the amplitude over parieto-occipital leads was enhanced in the SRT. The strongest intensity of the frontal negative expectancy wave over prefrontal leads in the Go/No-go task could be attributed to the largest uncertainty about the target presentation and subsequent motor response selection and execution. The enhanced sensory readiness in the SRT can be related to either an increased visual readiness associated with task requirements or a reduced overlap with proactive processing on the scalp.

Mindfulness Training Improves Attention: Evidence from Behavioral and Event-related Potential Analyses

Mindfulness meditation helps to improve attentional capacity. However, the neural correlates that indicate the mechanism through which mindfulness improves attention are unclear. To address this gap, we aimed to assess the effects of mindfulness training on sustained attentional capacity. Event-related potentials (ERPs) associated with the modified sustained attention response task (mSART) were used in this study. A total of 45 college students were randomly assigned to either the mindfulness group (n = 21) or the control group (n = 24). Participants in the mindfulness group received a three-week mindfulness training. The self-report results showed that the mindfulness group reported higher mindfulness scores (observing and non-judgment of inner experiences) after the training. The mindfulness group also scored lower on the state anxiety than the control group. Behavioral results also showed that self-caught mind wandering in the mindfulness group significantly decreased after the training, and the mindfulness group showed a faster response after the training. The ERP results showed that N2 amplitudes in the post-test were significantly greater than those in the pre-test in the mindfulness group. We did not find any interactions between group and time for P3. The findings suggest that mindfulness training can effectively improve sustained attentional capacity, as indicated by reduced mind wandering and increased N2 responses.

Attention neuroenhancement through tDCS or neurofeedback: a randomized, single-blind, controlled trial

Neurofeedback and transcranial Direct Current Stimulation (tDCS) are promising techniques for neuroenhancement of attentional performance. As far as we know no study compared both techniques on attentional performance in healthy participants. We compared tDCS and neurofeedback in a randomized, single-blind, controlled experiment assessing both behavioral (accuracy and time reaction) and electrophysiological (N1, P1, and P3 components) data of participants responding to the Attention Network Task (ANT). Eighty volunteers volunteered for this study. We adopted standard protocols for both techniques, i.e., a Sensorimotor Rhythm (SMR) protocol for neurofeedback and the right DLPFC anodal stimulation for tDCS, applied over nine sessions (two weeks). We did not find significant differences between treatment groups on ANT, neither at the behavioral nor at the electrophysiological levels. However, we found that participants from both neuromodulation groups, irrespective of if active or sham, reported attentional improvements in response to the treatment on a subjective scale. Our study adds another null result to the neuromodulation literature, showing that neurofeedback and tDCS effects are more complex than previously suggested and associated with placebo effect. More studies in neuroenhancement literature are necessary to fully comprehend neuromodulation mechanisms.

The steady state visual evoked potential (SSVEP) tracks "sticky" thinking, but not more general mind-wandering

For a large proportion of our daily lives, spontaneously occurring thoughts tend to disengage our minds from goal-directed thinking. Previous studies showed that EEG features such as the P3 and alpha oscillations can predict mind-wandering to some extent, but only with accuracies of around 60%. A potential candidate for improving prediction accuracy is the Steady-State Visual Evoked Potential (SSVEP), which is used frequently in single-trial contexts such as brain-computer interfaces as a marker of the direction of attention. In this study, we modified the sustained attention to response task (SART) that is usually employed to measure spontaneous thought to incorporate the SSVEP elicited by a 12.5-Hz flicker. We then examined whether the SSVEP could track and allow for the prediction of the stickiness and task-relatedness dimensions of spontaneous thought. Our results show that the SSVEP evoked by flickering words was able to distinguish between more and less sticky thinking but not between whether a participant was on- or off-task. This suggests that the SSVEP is able to track spontaneous thinking when it is strongly disengaged from the task (as in the sticky form of off-task thinking) but not off-task thought in general. Future research should determine the exact dimensions of spontaneous thought to which the SSVEP is most sensitive.

Mind Wandering Impedes Response Inhibition by Affecting the Triggering of the Inhibitory Process

Mind wandering is a state in which our mental focus shifts toward task-unrelated thoughts. Although it is known that mind wandering has a detrimental effect on concurrent task performance (e.g., decreased accuracy), its effect on executive functions is poorly studied. Yet the latter question is relevant to many real-world situations, such as rapid stopping during driving. Here, we studied how mind wandering would affect the requirement to subsequently stop an incipient motor response. In healthy adults, we tested whether mind wandering affected stopping and, if so, which component of stopping was affected: the triggering of the inhibitory brake or the implementation of the brake following triggering. We observed that during mind wandering, stopping latency increased, as did the percentage of trials with failed triggering. Indeed, 67% of the variance of the increase in stopping latency was explained by increased trigger failures. Thus, mind wandering primarily affects stopping by affecting the triggering of the brake.

Electrophysiological markers of mind wandering: A systematic review

The ability to mentally wander away from the external environment is a remarkable feature of the human mind. Although recent years have witnessed a surge of interest in examining mind wandering using EEG, there is no comprehensive review that summarizes and accounts for the variable findings. Accordingly, we conducted a systematic review that synthesizes evidence from EEG studies that examined the electrophysiological measures of mind wandering. Our search yielded 42 studies that met eligibility criteria. The reviewed literature converges on a reduction in the amplitude of canonical ERP components (i.e., P1, N1 and P3) as the most reliable markers of mind wandering. Spectral findings were less robust, but point towards greater activity in lower frequency bands, (i.e., delta, theta, and alpha), as well as a decrease in beta band activity, during mind wandering compared to on-task states. The variability in these findings appears to be modulated by the task context. To integrate these findings, we propose an electrophysiological account of mind wandering that explains how the brain supports this inner experience. Conclusions drawn from this work will inform future endeavours in basic science to map out electrophysiological patterns underlying mind wandering and in translational science using EEG to predict the occurrence of this phenomenon.

Modulation of neurocognitive functions associated with action preparation and early stimulus processing by response-generated feedback

Receiving feedback on action correctness is a relevant factor in learning, but only a few recent studies have investigated the neural bases involved in feedback processing and its consequences on performance. Several event-related potentials (ERP) studies investigated the feedback-related negativity, which is an ERP occurring after the presentation of a feedback stimulus. In contrast, the present study investigates the effect of providing feedback on brain activities before and after the presentation of an imperative stimulus with the aim to show how this could have an impact on cognitive functions related to anticipatory and post-stimulus task processing. Participants performed a standard visuomotor task and a modified version of the same task in which feedback sounds were emitted when participants committed performance errors. Overall, results showed that in the feedback task subjects have better cognitive control than in the standard task. All behavioral measures were improved in the feedback task. At the brain level, all the studied components were modulated by the presence of the feedback cue. Results pointed to a possible increase of anticipatory activity in the prefrontal cortex, a reduction of perceptual awareness in areas previously associated with the anterior insular cortex, and an increase of activity associated with selective attention in sensory cortices.

ADHD and Interfering Thoughts in High and Low Conflict Conditions

BACKGROUND

Individuals with an ADHD diagnosis have increased levels of interfering thoughts, especially in the form of mind wandering. This was mostly investigated in sustained attention tasks; hence it is unclear whether the findings are only due to their difficulties in those types of tasks. Moreover, it is unclear how the amount of control invested in the task will affect those differences between control and ADHD groups.

METHOD

ADHD and matched control groups performed the Stroop task under high and low conflict conditions while measuring their interfering thoughts level.

RESULTS

Individuals with ADHD have more interfering thoughts compared to a control group even when they are able to change their control level according to the task conflict.

CONCLUSION

Interfering thoughts are an independent predictor of ADHD impairments, observed regardless of the degree of control invested in the task.

The role of trataka in ameliorating visual strain and promoting psychological well-being during prolonged use of digital displays: A randomized controlled trial

BACKGROUND: The prolonged usage of digital displays leads to visual strain and, in turn, impairs psychological well-being. The practice of Yoga is said to enhance psychological functions and reduce visual strain. OBJECTIVE: The present study assessed the effect of the trataka (Yogic visual concentration) practice on the visual strain, mind-wandering, and mindfulness. METHODS: One hundred six volunteers equally distributed in the experimental and control groups completed the study. Visual Fatigue Scale (VFS), visual symptoms checklist (VSC), mind-wandering questionnaire (MWQ), and State Mindfulness Attention Awareness Scale (SMAAS) were administered at baseline and at the end of two weeks. RESULTS: All variables were similar at the baseline in both groups, and significant differences were noted at the end of two weeks between both groups. There was a significant reduction in VFS and VSC scores, MWQ, along with an increase in SMAAS scores in the experimental group. Although there were significant changes in VFS, MWQ, and SMAAS in the control group, the magnitude of change was minimal. CONCLUSIONS: The practice of trataka was found to reduce the visual strain, mind wandering while improving the state mindfulness. The practice can be implemented to mitigate visual strain and associated psychological implications due to prolonged exposure to digital displays, which has increased during the COVID-19 pandemic.

The effects of acute stress on attentional networks and working memory in females

Neurobiological models indicate that acute stress facilitates bottom-up stimulus processing while impairing top-down executive control. To test this hypothesis, the present study investigated the effects of acute stress on behavioural and electrophysiological measures of human attentional networks, and behavioural measures of working memory. Forty-five female participants (M_age = 22.1, SD = 2.4) performed the Attention Network Test (ANT) and the n-back task before and after the Maastricht Acute Stress Test (MAST; n = 23) or a non-stressful MAST-placebo (n = 22). Subjective distress ratings and salivary cortisol concentrations revealed a successful stress induction. Increased salivary cortisol at baseline was associated with slower reaction times across both tasks, suggesting a general detrimental effect of cortisol on cognitive functioning. Despite these findings, however, the hypothesised effects of the acute stress manipulation were not found for either task. Supplementary analyses indicated that these results were unrelated to the magnitude or duration of the stress response. Our results therefore suggest the standard version of the ANT may be insensitive to the effects of acute stress, and that higher cognitive loads may be necessary to observe stress effects on the n-back task.

Detection of mind wandering using EEG: Within and across individuals

Mind wandering is often characterized by attention oriented away from an external task towards our internal, self-generated thoughts. This universal phenomenon has been linked to numerous disruptive functional outcomes, including performance errors and negative affect. Despite its prevalence and impact, studies to date have yet to identify robust behavioral signatures, making unobtrusive, yet reliable detection of mind wandering a difficult but important task for future applications. Here we examined whether electrophysiological measures can be used in machine learning models to accurately predict mind wandering states. We recorded scalp EEG from participants as they performed an auditory target detection task and self-reported whether they were on task or mind wandering. We successfully classified attention states both within (person-dependent) and across (person-independent) individuals using event-related potential (ERP) measures. Non-linear and linear machine learning models detected mind wandering above-chance within subjects: support vector machine (AUC = 0.715) and logistic regression (AUC = 0.635). Importantly, these models also generalized across subjects: support vector machine (AUC = 0.613) and logistic regression (AUC = 0.609), suggesting we can reliably predict a given individual's attention state based on ERP patterns observed in the group. This study is the first to demonstrate that machine learning models can generalize to "never-seen-before" individuals using electrophysiological measures, highlighting their potential for real-time prediction of covert attention states.

The effects of direct current stimulation and random noise stimulation on attention networks

Attention is a complex cognitive process that selects specific stimuli for further processing. Previous research suggested the existence of three attentional networks: alerting, orienting and executive. However, one important topic is how to enhance the efficiency of attentional networks. In this context, understanding how this system behaves under two different modulatory conditions, namely transcranial direct current stimulation (tDCS) and transcranial Random Noise Stimulation (tRNS), will provide important insights towards the understanding of the attention network system. Twenty-seven healthy students took part on a randomized single-blinded crossover study, testing the effects that involved three modalities of unilateral stimulation (tRNS, anodal tDCS, and sham) over the DLPFC, during the performance of the attention network test (ANT) in three different conditions: standard, speed and accuracy. Results showed that tRNS was able to increase attention during more complex situations, namely by increasing alerting and decreasing conflict effect in the executive network. Under the Speed condition, tRNS increased efficiency of the alerting network, as well as under the more demanding conflict network, tRNS overall increased the performance when comparing to sham. No statistical significant effects of tDCS were observed. These results are compatible with the attention requiring the synchronization of pre-existing networks, rather the reinforcement or creation of new pathways.

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.

The Role of Task Complexity on Frontal Event-related Potentials and Evidence in Favour of the Epiphenomenal Interpretation of the Go/No-Go N2 Effect

It is well established that task complexity can affect both performance and brain processing. Event-related potentials (ERPs) studies have shown modulation of the well-known N2 and P3 components. However, limited information is available on the recently described frontal components associated with processing within the anterior insular cortex. This work aims to shed light on the effect of task complexity on the insular ERP components associated with perceptual (pN1) and sensory-motor awareness (pP1), as well as with stimulus-response mapping (the pP2). Moreover, this comparison of tasks with different complexity was expected to provide a new point of view on the debate on inhibitory or conflict monitoring role of the N2 component. Thirty-two participants were assigned to two groups: one performed an easy response task (with only a target and a non-target stimulus), the other one performed a complex response task (with two target and two non-target stimuli). The task comparison revealed enhanced pP1 and pP2 components but a reduced N2 component in the complex paradigm. These results suggest that task complexity may entail greater processing strength in the anterior insula functions associated with endogenous perceptual processing. Also, findings on the N2 activity provide evidence against both the inhibitory and conflict interpretation of this component, as the N2 amplitude was reduced in the complex task.

Preparatory ERPs in visual, auditory, and somatosensory discriminative motor tasks

Previous event-related potential (ERP) studies mainly from the present research group showed a novel component, that is, the prefrontal negativity (pN), recorded in visual-motor discriminative tasks during the pre-stimulus phase. This component is concomitant to activity related to motor preparation, that is, the Bereitschaftspotential (BP). The pN component has been reported in experiments based on the visual modality only; for other modalities (acoustic and/or somatosensory) the presence of the pN warrants further investigation. This study represents a first step toward this direction; indeed, we aimed at describing the pN and the BP components in discriminative response tasks (DRTs) for three sensory modalities. In experiment 1 ERPs were recorded in 29 adults in visual and auditory DRT; an additional group of 15 adults participated to a somatosensory DRT (experiment 2). In line with previous results both the pN and the BP were clearly detectable in the visual modality. In the auditory modality the prefrontal pN was not detectable directly; however, the pN could be derived by subtraction of separate EEG traces recorded in a "passive" version of the same auditory task, in which motor responses were not required. In the somatosensory modality both the pN and the BP were detectable, although with lower amplitudes with respect to other two sensory modalities. Overall, regardless of the sensory modality, anticipatory task-related pN and BP components could be detected (or derived by subtraction) over both the prefrontal and motor cortices. These results support the view that anticipatory processes share common components among sensory modalities.

Impact of Chronic Stress on Attention Control: Evidence from Behavioral and Event-Related Potential Analyses

Chronic stress affects brain function, so assessing its hazards is important for mental health. To overcome the limitations of behavioral data, we combined behavioral and event-related potentials (ERPs) in an attention network task. This task allowed us to differentiate between three specific aspects of attention: alerting, orienting, and execution. Forty-one participants under chronic stress and 31 non-stressed participants were enrolled. On the performance level, the chronically stressed group showed a significantly slower task response and lower accuracy. Concerning ERP measures, smaller cue-N1, cue-N2, and larger cue-P3 amplitudes were found in the stressed group, indicating that this group was less able to assign attention to effective information, i.e., they made inefficient use of cues and had difficulty in maintaining alerting. In addition, the stressed group showed larger target-N2 amplitudes, indicating that this group needed to allocate more cognitive resources to deal with the conflict targets task. Subgroup analysis revealed lower target-P3 amplitudes in the stressed than in the non-stressed group. Group differences associated with the attention networks were found at the ERP level. In the stressed group, excessive depletion of resources led to changes in attention control. In this study, we examined the effects of chronic stress on individual executive function from a neurological perspective. The results may benefit the development of interventions to improve executive function in chronically stressed individuals.

Predicting task-general mind-wandering with EEG

Mind-wandering refers to the process of thinking task-unrelated thoughts while performing a task. The dynamics of mind-wandering remain elusive because it is difficult to track when someone’s mind is wandering based only on behavior. The goal of this study is to develop a machine-learning classifier that can determine someone’s mind-wandering state online using electroencephalography (EEG) in a way that generalizes across tasks. In particular, we trained machine-learning models on EEG markers to classify the participants’ current state as either mind-wandering or on-task. To be able to examine the task generality of the classifier, two different paradigms were adopted in this study: a sustained attention to response task (SART) and a visual search task. In both tasks, probe questions asking for a self-report of the thoughts at that moment were inserted at random moments, and participants’ responses to the probes were used to create labels for the classifier. The 6 trials preceding an off-task response were labeled as mind-wandering, whereas the 6 trials predicting an on-task response were labeled as on-task. The EEG markers used as features for the classifier included single-trial P1, N1, and P3, the power and coherence in the theta (4–8 Hz) and alpha (8.5–12 Hz) bands at PO7, Pz, PO8, and Fz. We used a support vector machine as the training algorithm to learn the connection between EEG markers and the current mind-wandering state. We were able to distinguish between on-task and off-task thinking with an accuracy ranging from 0.50 to 0.85. Moreover, the classifiers were task-general: The average accuracy in across-task prediction was 60%, which was above chance level. Among all the extracted EEG markers, alpha power was most predictive of mind-wandering.

Pearls and pitfalls in brain functional analysis by event-related potentials: a narrative review by the Italian Psychophysiology and Cognitive Neuroscience Society on methodological limits and clinical reliability-part I

Event-related potentials (ERPs) are obtained from the electroencephalogram (EEG) or the magnetoencephalogram (MEG, event-related fields (ERF)), extracting the activity that is time-locked to an event. Despite the potential utility of ERP/ERF in cognitive domain, the clinical standardization of their use is presently undefined for most of procedures. The aim of the present review is to establish limits and reliability of ERP medical application, summarize main methodological issues, and present evidence of clinical application and future improvement. The present section of the review focuses on well-standardized ERP methods, including P300, Contingent Negative Variation (CNV), Mismatch Negativity (MMN), and N400, with a chapter dedicated to laser-evoked potentials (LEPs). One section is dedicated to proactive preparatory brain activity as the Bereitschaftspotential and the prefrontal negativity (BP and pN). The P300 and the MMN potentials have a limited but recognized role in the diagnosis of cognitive impairment and consciousness disorders. LEPs have a well-documented usefulness in the diagnosis of neuropathic pain, with low application in clinical assessment of psychophysiological basis of pain. The other ERP components mentioned here, though largely applied in normal and pathological cases and well standardized, are still confined to the research field. CNV, BP, and pN deserve to be largely tested in movement disorders, just to explain possible functional changes in motor preparation circuits subtending different clinical pictures and responses to treatments.

Neuromodulating attention and mind-wandering processes with multi-session real-time electroencephalogram

Previous studies showed the efficacy of a single session real-time electroencephalogram (rtEEG) protocols in sensorimotor rhythm (SMR) or Theta up-training. However, the impact of this training on sustained or mind-wandering attention was only modest. This could be explained by the lack of specificity in distinct rtEEG training protocols given their limitation in inhibiting or decreasing the amplitude of down-trained bands. Additionally, multiple sessions of rtEEG in up-training/down-training SMR (sensorimotor rhythm) and Theta along with better ways of tracking sustained and mind-wandering attention protocols may be required to achieve consistent effects. Here we describe the effects of a 10-session trial of up-training/down-training SMR or Theta (SMR⇑Theta⇓; Theta⇑SMR⇓), looking at the effects of 2 rtEEG training protocols in 2 n of 1 subject designs. We also tested to impact of this training in sustained and mind-wandering attention during the course of a Sustained Attention Response Task (SART). The present trial confirmed the potentiality of a multi-session protocol in up-training Theta or SMR and, as consequence, increasing sustained attention (Theta up-training) and mind-wandering attention (SMR up-training). However, the simultaneous increase of the Theta amplitude in the SMR⇑Theta⇓ (and the more modest increase of the SMR amplitude in Theta⇑SMR⇓) reduced the specificity of the rtEEG training. Future studies should build on the potentiality of extended rtEEG protocols on this attention paradigm but increasing the specificity of the trained EEG bands choosing less tedious/more motivating feedback instruments (SMR⇑Theta⇓) and conducting the Theta⇑SMR⇓ training eyes closed.

Awareness of perception and sensory-motor integration: ERPs from the anterior insula

The present work follows recent evidences of studies showing that visual stimuli evoke two early prefrontal event-related potentials (ERP) concomitant to the canonical occipital activities, but originating within the anterior insula (the pN1 and the pP1 components). To clarify the exogenous/endogenous nature of these components, we performed two experiments in which stimulus physical features (Experiment 1) and motor demands of the task (Experiment 2) were considered. In a simple response task (SRT), low-visibility stimuli evoked larger pN1 over the prefrontal areas (Experiment 1) with respect to high-visibility stimuli; in contrast, the occipital P1 component (concomitant to the pN1) had reduced amplitude in the low-visibility condition as expected. Furthermore, the latency of the P1, pN1 and pP1 was slower in the low-visibility condition (from 8 to 18 ms), and the motor response was slowed down as well (on average 14 ms). Pre-stimulus analysis showed that low-visibility stimuli were preceded by greater motor readiness. On the other hand, Experiment 2 showed that, compared with the SRT, the request to passively view the same stimuli was associated with smaller pP1. ERP source analysis confirmed the anterior insula source of the prefrontal ERPs; we interpreted these activities as the correlate of two top-down perceptual processing: the sensory awareness (the pN1) and the awareness of the sensory-motor integration (the pP1), associated with the subjective experience of the visual perception and the conscious experience of the sensory-motor coupling, respectively.