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There is growing awareness across the neuroscience community that the replicability of findings about the relationship between brain activity and cognitive phenomena can be improved by conducting studies with high statistical power that adhere to well-defined and standardised analysis pipelines. Inspired by recent efforts from the psychological sciences, and with the desire to examine some of the foundational findings using electroencephalog-raphy (EEG), we have launched #EEGManyLabs, a large-scale international collaborative replication effort. Since its discovery in the early 20th century, EEG has had a profound in-fluence on our understanding of human cognition, but there is limited evidence on the replicability of some of the most highly cited discoveries. After a systematic search and se-lection process, we have identified 27 of the most influential and continually cited studies in the field. We plan to directly test the replicability of key findings from 20 of these studies in teams of at least three independent laboratories. The design and protocol of each replication effort will be submitted as a Registered Report and peer-reviewed prior to data collection. Prediction markets, open to all EEG researchers, will be used as a forecasting tool to examine which findings the community expects to replicate. This project will update our confidence in some of the most influential EEG findings and generate a large open access database that can be used to inform future research practices. Finally, through this international effort, we hope to create a cultural shift towards inclusive, high-powered multi-laboratory collaborations. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Statistical power in cognitive neuroimaging experiments is often very low. Low sample size can reduce the likelihood of detecting real effects (false negatives) and increase the risk of detecting non-existing effects by chance (false positives). Here we document our experience of leveraging a relatively unexplored method of collecting a large sample size for simple electroencephalography (EEG) studies: by recording EEG in the community during public engagement and outreach events. We collected data from 346 participants (189 females, age range 6-76 years) over 6 days, totalling 29 hours, at local science festivals. Occipital alpha activity (6-15 Hz) was filtered from 30 seconds of signal, recorded from a single electrode placed on the occipital midline (Oz) while participants rested with their eyes closed. A total of 289 good quality datasets were obtained. Using this community-based approach, we were able to replicate controlled, lab-based findings: IAF increased during childhood, reaching a peak frequency of 10.28 Hz at 28.1 years old, and slowed again in middle and older age. Total alpha power decreased linearly, but the aperiodic-adjusted alpha power did not change over the lifespan. Aperiodic slopes and intercepts were highest in the youngest participants. There were no associations between these EEG indexes and self-reported fatigue, measured by the Multidimensional Fatigue Inventory. Finally, we present a set of important considerations for researchers who wish to collect EEG data within public engagement and outreach environments.

Shifts in spatial attention are associated with variations in alpha-band (α, 8–14 Hz) activity, specifically in inter-hemispheric imbalance. The underlying mechanism is attributed to local α-synchronisation, which regulates local inhibition of neural excitability, and fronto-parietal synchronisation reflecting long-range communication. The direction-specific nature of this neural correlate brings forward its potential as a control signal in brain-computer interfaces (BCI). In the present study, we explored whether long-range α-synchronisation presents lateralised patterns dependent on voluntary attention orienting and whether these neural patterns can be picked up at a single-trial level to provide a control signal for active BCI. We collected electroencephalography (EEG) data from a cohort of healthy adults (n = 10) while performing a covert visuospatial attention (CVSA) task. The data shows a lateralised pattern of α-band phase coupling between frontal and parieto-occipital regions after target presentation, replicating previous findings. This pattern, however, was not evident during the cue-to-target orienting interval, the ideal time window for BCI. Furthermore, decoding the direction of attention trial-by-trial from cue-locked synchronisation with support vector machines (SVM) was at chance-level. The present findings suggest EEG may not be capable of detecting long-range α-synchronisation in attentional orienting on a single-trial basis and, thus, highlight the limitations of this metric as a reliable signal for BCI control.SIGNIFICANCE STATEMENTCognitive neuroscience advances should ideally have a real-world impact, with an obvious avenue for transference being BCI applications. The hope is to faithfully translate user-generated brain endogenous states into control signals to actuate devices. A paramount challenge for transfer is to move from group-level, multi-trial average approaches to single-trial level. Here, we evaluated the feasibility of single-trial estimation of phase synchrony across distant brain regions. Although many studies link attention to long-range synchrony modulation, this metric has never been used to control BCI. We present a first attempt of a synchrony-based BCI that, albeit unsuccessful, should help break new ground to map endogenous attention shifts to real-time control of brain-computer actuated systems.

First published February 7, 2023 Shifts in spatial attention are associated with variations in α band (α, 8–14 Hz) activity, specifically in interhemispheric imbalance. The underlying mechanism is attributed to local α-synchronization, which regulates local inhibition of neural excitability, and frontoparietal synchronization reflecting long-range communication. The direction-specific nature of this neural correlate brings forward its potential as a control signal in brain-computer interfaces (BCIs). In the present study, we explored whether long-range α-synchronization presents lateralized patterns dependent on voluntary attention orienting and whether these neural patterns can be picked up at a single-trial level to provide a control signal for active BCI. We collected electroencephalography (EEG) data from a cohort of healthy adults (n = 10) while performing a covert visuospatial attention (CVSA) task. The data show a lateralized pattern of α-band phase coupling between frontal and parieto-occipital regions after target presentation, replicating previous findings. This pattern, however, was not evident during the cue-to-target orienting interval, the ideal time window for BCI. Furthermore, decoding the direction of attention trial-by-trial from cue-locked synchronization with support vector machines (SVMs) was at chance level. The present findings suggest EEG may not be capable of detecting long-range α-synchronization in attentional orienting on a single-trial basis and, thus, highlight the limitations of this metric as a reliable signal for BCI control. This research was supported by the Agència de Gestió d’Ajuts Universitaris i de Recerca Generalitat de Catalunya Grant 2017 SGR 1545. This project has been co-funded with 50% by the European Regional Development Fund under the framework of the FEDER Operative Programme for Catalunya 2014-2020 Ministerio de Ciencia e Innovación (Ref: PID2019-108531GB-I00 AEI/FEDER).

First published: 06 December 2021 To make sense of ambiguous and, at times, fragmentary sensory input, the brain must rely on a process of active interpretation. At any given moment, only one of several possible perceptual representations prevails in our conscious experience. Our hypothesis is that the competition between alternative representations induces a pattern of neural activation resembling cognitive conflict, eventually leading to fluctuations between different perceptual outcomes in the case of steep competition. To test this hypothesis, we probed changes in perceptual awareness between competing images using binocular rivalry. We drew our predictions from the conflict monitoring theory, which holds that cognitive control is invoked by the detection of conflict during information processing. Our results show that fronto-medial theta oscillations (5–7 Hz), an established electroencephalography (EEG) marker of conflict, increases right before perceptual alternations and decreases thereafter, suggesting that conflict monitoring occurs during perceptual competition. Furthermore, to investigate conflict resolution via attentional engagement, we looked for a neural marker of perceptual switches as by parieto-occipital alpha oscillations (8–12 Hz). The power of parieto-occipital alpha displayed an inverse pattern to that of fronto-medial theta, reflecting periods of high interocular inhibition during stable perception, and low inhibition around moments of perceptual change. Our findings aim to elucidate the relationship between conflict monitoring mechanisms and perceptual awareness. H2020 Marie Skłodowska-Curie Actions, Grant/Award Number: 794649; Universitat Pompeu Fabra; FEDER Operative Programme for Catalunya 2014–2020; IkerBasque Research Fellowships; Ramon y Cajal, Grant/Award Number: RYC2019-027538-I; University Pompeu Fabra; AGAUR Generalitat de Catalunya, Grant/Award Numbers: 2017 SGR 1545, FI-DGR 2019; Ministerio de Ciencia e Innovaci on, Grant/Award Number: PID2019-108531GB-I00 AEI/FEDER

Electrical brain oscillations reflect fluctuations in neural excitability. Fluctuations in the alpha band (α, 8-12 Hz) in the occipito-parietal cortex are thought to regulate sensory responses, leading to cyclic variations in visual perception. Inspired by this theory, some past and recent studies have addressed the relationship between α-phase from extra-cranial EEG and behavioural responses to visual stimuli in humans. The latest studies have used offline approaches to confirm α-gated cyclic patterns. However, a particularly relevant implication is the possibility to use this principle online for real-time neurotechnology, whereby stimuli are time-locked to specific α-phases leading to predictable outcomes in performance. Here we aimed at providing a proof-of-concept for such real-time neurotechnology. Participants performed a speeded response task to visual targets that were presented upon a real-time estimation of the α-phase via an EEG closed-loop brain-computer interface (BCI). We predicted, according to the theory, a modulation of reaction times (RTs) along the α-cycle. Our BCI system achieved reliable trial-to-trial phase-locking of stimuli to the phase of individual occipito-parietal α-oscillations. Yet, the behavioural results did not support a consistent relation between RTs and the phase of the α-cycle neither at group nor single participant levels. We must conclude that although the α-phase might play a role in perceptual decisions from a theoretical perspective, its impact on EEG-based BCI application appears negligible.

This study explored brain responses to images that exploit incongruity as a creative technique, often used in advertising (i.e., surrealistic images). We hypothesized that these images would reveal responses akin to cognitive conflict resulting from incongruent trials in typical laboratory tasks (i.e., Stroop Task). Indeed, in many surrealistic images, common visual elements are juxtaposed to create un-ordinary associations with semantically conflicting representations. We expected that these images engage the conflict processing network that has been described in cognitive neuroscience theories. We addressed this hypothesis by measuring the power of mid-frontal Theta oscillations using EEG while participants watched images through a social media-like interface. Incongruent images, compared to controls, produced a significant Theta power increase, as predicted from the cognitive conflict theory. We also found increased memory for incongruent images one week after exposure, compared to the controls. These findings provide evidence for the incongruent images to effectively engage the viewer's cognitive control and boost memorability. The results of this study provide validation of cognitive theories in real-life scenarios (i.e., surrealistic ads or art) and offer insights regarding the use of neural correlates as effectiveness metrics in advertising., This research was supported by the Ministerio de Economia y Competitividad (PSI2016-75558-P AEI/FEDER), AGAUR Generalitat de Catalunya (2017 SGR 1545), and the European Research Council (PoC- 727595 to SSF) and. M.R. was supported by a Marie Skłodowska- Curie fellowship (Ctrl Code – 794649 - H2020- MSCA-IF-2017 to MR).

In everyday life multisensory events, such as a glass crashing on the floor, the different sensory inputs are often experienced as simultaneous, despite the sensory processing of sound and sight within the brain are temporally misaligned. This lack of cross-modal synchrony is the unavoidable consequence of different light and sound speeds, and their different neural transmission times in the corresponding sensory pathways. Hence, cross-modal synchrony must be reconstructed during perception. It has been suggested that spontaneous fluctuations in neural excitability might be involved in the temporal organisation of sensory events during perception and account for variability in behavioural performance. Here, we addressed the relationship between ongoing brain oscillations and the perception of cross-modal simultaneity. Participants performed an audio-visual simultaneity judgement task while their EEG was recorded. We focused on pre-stimulu activity, and found that the phase of neural oscillations at 13 ± 2 Hz 200 ms prior to the stimulus correlated with subjective simultaneity of otherwise identical sound-flash events. Remarkably, the correlation between EEG phase and behavioural report occurred in the absence of concomitant changes in EEG amplitude. The probability of simultaneity perception fluctuated significantly as a function of pre-stimulus phase, with the largest perceptual variation being accounted for phase angles nearly 180º apart. This pattern was strongly reliable for sound-flash pairs but not for flash-sound pairs. Overall, these findings suggest that the phase of ongoing brain activity might underlie internal states of the observer that influence cross-modal temporal organisation between the senses and, in turn, subjective synchrony.

Electrical brain oscillations reflect fluctuations in neural excitability. Fluctuations in the alpha band (α, 8–12 Hz) in the occipito‐parietal cortex are thought to regulate sensory responses, leading to cyclic variations in visual perception. Inspired by this theory, some past and recent studies have addressed the relationship between α‐phase from extra‐cranial EEG and behavioural responses to visual stimuli in humans. The latest studies have used offline approaches to confirm α‐gated cyclic patterns. However, a particularly relevant implication is the possibility to use this principle online, whereby stimuli are time‐locked to specific α‐phases leading to predictable outcomes in performance. Here, we aimed at providing a proof of concept for such real‐time neurotechnology. Participants performed a speeded response task to visual targets that were presented upon a real‐time estimation of the α‐phase via an EEG closed‐loop brain–computer interface (BCI). According to the theory, we predicted a modulation of reaction times (RTs) along the α‐cycle. Our BCI system achieved reliable trial‐to‐trial phase locking of stimuli to the phase of individual occipito‐parietal α‐oscillations. Yet, the behavioural results did not support a consistent relation between RTs and the phase of the α‐cycle neither at group nor at single participant levels. We must conclude that although the α‐phase might play a role in perceptual decisions from a theoretical perspective, its impact on EEG‐based BCI application appears negligible. This research was supported by the Ministerio de Economia y Competitividad (PSI2016-75558-P AEI/FEDER to S.S.F.), AGAUR Generalitat de Catalunya (2014SGR856 to S.S.F.), Explora Ciencia 2015 (AEI - PSI2015-72568-EXP to M.R.). M.R. was also supported by the European Commission Individual Fellowship (Ctrl Code – 794649, H2020-MSCA-IF-2017).

A crucial aspect when learning a language is discovering the rules that govern how words are combined in order to convey meanings. Because rules are characterized by sequential co-occurrences between elements (e.g., “These cupcakes are unbelievable”), tracking the statistical relationships between these elements is fundamental. However, purely bottom-up statistical learning alone cannot fully account for the ability to create abstract rule representations that can be generalized, a paramount requirement of linguistic rules. Here, we provide evidence that, after the statistical relations between words have been extracted, the engagement of goal-directed attention is key to enable rule generalization. Incidental learning performance during a rule-learning task on an artificial language revealed a progressive shift from statistical learning to goal-directed attention. In addition, and consistent with the recruitment of attention, functional MRI (fMRI) analyses of late learning stages showed left parietal activity within a broad bilateral dorsal frontoparietal network. Critically, repetitive transcranial magnetic stimulation (rTMS) on participants’ peak of activation within the left parietal cortex impaired their ability to generalize learned rules to a structurally analogous new language. No stimulation or rTMS on a nonrelevant brain region did not have the same interfering effect on generalization. Performance on an additional attentional task showed that this rTMS on the parietal site hindered participants’ ability to integrate “what” (stimulus identity) and “when” (stimulus timing) information about an expected target. The present findings suggest that learning rules from speech is a two-stage process: following statistical learning, goal-directed attention—involving left parietal regions—integrates “what” and “when” stimulus information to facilitate rapid rule generalization., European Research Council (ERC), Spanish Ministerio de Ciencia e Innovacio PRIME RdD-B, European Research Council (ERC) 727595, Juan de la Cierva Post-Doctorate Fellowship JCI-2012-12335, Ministerio de Economia y Competividad

To make sense of ambiguous and, at times, incomplete sensory input, the brain relies on a process of active interpretation. At any given moment, only one of several possible perceptual outcomes prevails in our conscious experience. Our hypothesis is that the competition between alternative representations induces cognitive conflict, eventually leading to fluctuations between different perceptual interpretations. We used binocular rivalry, a popular protocol to probe changes in perceptual awareness [1–3] and drew on the conflict monitoring theory, which holds that cognitive control is invoked by the detection of conflict during information processing. We looked for an increase in power of fronto-medial theta oscillations (5-7 Hz), an established EEG marker of conflict detection [4–7]. Our results show that fm-theta power increases right before perceptual alternations and decreases thereafter, suggesting that conflict monitoring is related to perceptual competition. Furthermore, to investigate conflict resolution via attentional engagement, as held by the conflict monitoring theory [8], we also looked for changes in parieto-occipital alpha oscillations (8-12 Hz) associated to perceptual switches. These oscillations have been associated to attention allocation via functional inhibition in sensory cortices [9–12]. The power of parieto-occipital alpha was inversely related to that of fm-theta, reflecting periods of high inter-ocular inhibition during stable perception, and low inhibition around moments of perceptual change. Our findings validate a prediction made 20 years ago in the seminal paper formulating the conflict monitoring theory, and establish a previously unknown link between conflict mechanisms and the processes leading to perceptual awareness.HighlightsBinocular rivalry induces conflict between competing perceptual representationsMid-frontal theta power increases around the resolution of perceptual conflictPosterior alpha decreases reflect neural excitability around perceptual switchesThe results link cognitive conflict theory with perceptual inference

Surrealistic imagery juxtaposes common visual elements to create un-ordinary associations with semantically conflicting representations. We hypothesize that these images engage the conflict processing network that has been described in cognitive neuroscience theories, and probed with laboratory protocols such as the Stroop or Flanker tasks. We addressed this hypothesis by measuring mid-frontal Theta power using EEG while participants watched surrealistic images through a social media-like interface. Surrealistic images, compared to controls, produced a significant Theta power increase, as predicted from cognitive conflict theory. We also found increased memory for surrealistic images one week after exposure, compared to the controls. These findings provide evidence for the surrealistic artistic strategy to effectively engage viewer’ s cognitive control and boost memorability. In these studies, we provide validation of cognitive theories in real-life scenarios and insights regarding the use of neural correlates as effectiveness metrics in creative communication, as well as the arts.

The interactions between the senses are essential for cognitive functions such as perception, attention, and action planning. Past research helped understanding of multisensory processes in the laboratory. Yet, the efforts to extrapolate these findings to the real-world are scarce. Extrapolation to real-world contexts is important for practical and theoretical reasons. Multisensory phenomena might be expressed differently in real-world settings compared to simpler laboratory situations. Some effects might become stronger, others may disappear, and new outcomes could be discovered. This Element discusses research that uncovers multisensory interactions under complex environments, with an emphasis on the interplay of multisensory mechanisms with other processes.

Neural oscillations in the low frequencies, roughly in the alpha band (α, 5-15 Hz), have been suggested to act as a gateway from sensation to perception. This hypothesis assumes discrete perception. In particular, the amplitude and the phase of the low frequency rhythm entails a cortical mechanism which paces the access of sensory information into the cognitive system. Evidence supporting this idea includes correlations between the phase of neural oscillations and behavioral performance in perception, spatial attention and working memory. Despite the widespread confidence in the theory, so far, the findings have been mostly based on a varied range of exploratory approaches and inferential group statistics. Here, we aimed at validating the involvement of low frequency cortical rhythm in perception and at providing a clear-cut EEG analysis pipeline. Such an analytical pipeline should support the adoption of a hypothesis-driven framework for future replications and applications. The design, the analyses and the statistical power of the present experiment were based on prior studies in which phase opposition was successfully found. However, our results provide evidence for the involvement of pre-stimulus oscillatory alpha amplitude but not phase in perception. We discuss the null findings from the present study within the existing literature.

In everyday life, we often must coordinate information across spatial locations and different senses for action. It is well known, for example, that reactions are faster when an imperative stimulus and its required response are congruent than when they are not, even if stimulus location itself is completely irrelevant for the task (the so-called Simon effect). However, because these effects have been frequently investigated in single-modality scenarios, the consequences of spatial congruence when more than one sensory modality is at play are less well known. Interestingly, at a behavioral level, the visual Simon effect vanishes in mixed (visual and tactile) modality scenarios, suggesting that irrelevant spatial information ceases to exert influence on vision. To shed some light on this surprising result, here we address the expression of irrelevant spatial information in EEG markers typical of the visual Simon effect (P300, theta power modulation, LRP) in mixed-modality contexts. Our results show no evidence for the visual- spatial information to affect performance at behavioral and neurophysiological levels. The absence of evidence of the neural markers of visual S-R conflict in the mixed-modality scenario implies that some aspects of spatial representations that are strongly expressed in single-modality scenarios might be bypassed. This research was supported by the Ministerio de Economia, Industria y Competividad (AEI/FEDER‐PSI2016‐75558‐P to SSF; and Explora Ciencia 2015 PSI2015‐72568‐EXP‐AEI to MR), and AGAUR Generalitat de Catalunya (2014SGR856 to SSF).

An intriguing question in neuroscience concerns how somatosensory events on the skin are represented in the human brain. Since Head and Holmes’ [1] neuropsychological dissociation between localizing touch on the skin and localizing body parts in external space, touch is considered to operate in a variety of spatial reference frames [2]. At least two representations of space are in competition during orienting to touch: a somatotopic one, reflecting the organization of the somatosensory cortex (S1) [3], and a more abstract, external reference frame that factors postural changes in relation to body parts and/or external space [4, 5]. Previous transcranial magnetic stimulation (TMS) studies suggest that the posterior parietal cortex (PPC) plays a key role in supporting representations as well as orienting attention in an external reference frame [4, 6]. Here, we capitalized on the TMS entrainment approach [7, 8], targeting the intraparietal sulcus (IPS). We found that frequency-specific (10 Hz) tuning of the PPC induced spatially specific enhancement of tactile detection that was expressed in an external reference frame. This finding establishes a tight causal link between a concrete form of brain activity (10 Hz oscillation) and a specific type of spatial representation, revealing a fundamental property of how the parietal cortex encodes information. This work was supported by grants from the European Research Council (StG-2010 263145), the Spanish Ministry of Science and Innovation (PSI2010-15426), and the Comissionat per a Universitats i Recerca del DIUE-Generalitat de Catalunya (SRG2009-092) to S.S.-F.

Background: Phosphenes induced by transcranial magnetic stimulation (TMS) are a subjectively described visual phenomenon employed in basic and clinical research as index of the excitability of retinotopically organized areas in the brain. Objective: Phosphene threshold estimation is a preliminary step in many TMS experiments in visual cognition for setting the appropriate level of TMS doses; however, the lack of a direct comparison of the available methods for phosphene threshold estimation leaves unsolved the reliability of those methods in setting TMS doses. The present work aims at fulfilling this gap. Methods: We compared the most common methods for phosphene threshold calculation, namely the Method of Constant Stimuli (MOCS), the Modified Binary Search (MOBS) and the Rapid Estimation of Phosphene Threshold (REPT). In two experiments we tested the reliability of PT estimation under each of the three methods, considering the day of administration, participants' expertise in phosphene perception and the sensitivity of each method to the initial values used for the threshold calculation. Results: We found that MOCS and REPT have comparable reliability when estimating phosphene thresholds, while MOBS estimations appear less stable. Conclusions: Based on our results, researchers and clinicians can estimate phosphene threshold according to MOCS or REPT equally reliably, depending on their specific investigation goals. We suggest several important factors for consideration when calculating phosphene thresholds and describe strategies to adopt in experimental procedures. M.R. was supported by Juan de la Cierva postdoctoral fellowship (JCI-2012-12335) from the Spanish Government.

Background & Aims: Chronic alcohol misuse, HCV infection and cirrhosis may cause cognitive alterations. The aim of the present study was to assess the influence of alcohol misuse, HCV infection and cirrhosis per se on the neuropsychological and electroencephalogram (EEG) profile and to evaluate the role of alcohol misuse and HCV infections as potential confounding factors in the detection of minimal hepatic encephalopathy. Methods: A comprehensive neuropsychological profile and EEG spectral parameters were obtained in six age-matched groups of 30 subjects each: (i) HCV-related hepatitis without cirrhosis, (ii) chronic alcohol abusers, (iii) patients with HCVrelated cirrhosis, (iv) alcohol-related cirrhosis, (v) cirrhosis not related to alcohol or HCV and (vi) healthy subjects. Cirrhotic patients were matched for MELD score. Results: The factor ‘cirrhosis’ was associated with low Phonemic Verbal Fluency (PVF) and Difference between Trail Making Test B and A (TMT) (B-A) (P < 0.001). Chronic alcohol misuse was associated with low PVF, TMT (B-A), Memory with Interference Task at 10 (ITM 10) and 30 s (ITM 30) (all P < 0.05). An interaction was found between the factors ‘cirrhosis’, ‘alcohol misuse’ and tests (P < 0.01). HCV hepatitis reduced ITM 10 (P < 0.05), but no interaction was found between ‘cirrhosis’, ‘HCV infection’ and tests (P = 0.14). The EEG parameters were mainly influenced by ‘cirrhosis’ (P < 0.05), and EEG alterations were more pronounced in patients with alcoholic cirrhosis (P = 0.04). Conclusions: Cirrhosis per se, chronic alcohol misuse and HCV infection were found to be associated with cognitive dysfunction. In patients with cirrhosis, the interaction with alcohol misuse further impinged on brain dysfunction.

Noninvasive brain stimulation (NIBS) is a unique method for studying cognitive function. For the study of cognition, NIBS has gained popularity as a complementary method to functional neuroimaging. By bypassing the correlative approaches of standard imaging techniques, it is possible to establish a putative relationship between brain cognition. In fact, functional neuroimaging data cannot demonstrate the actual role of a particular cortical activation in a specific function because an activated area may simply be correlated with task performance, rather than being responsible for it. NIBS can induce a temporary modification of performance only if the stimulated area is causally engaged in the task. In analogy with lesion studies, NIBS can provide information about where and when a particular process occurs. Based on this assumption, NIBS has been used in many different cognitive domains. However, one of the most interesting questions in neuroscience may not be where and when, but how cognitive activity occurs. Beyond localization approaches, NIBS can be employed to study brain mechanisms. NIBS techniques have the potential to influence behavior transiently by altering neuronal activity, which may have facilitatory or inhibitory behavioral effects. NIBS techniques include transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). TMS has been shown transiently to modulate neural excitability in a manner that is dependent mainly on the timing and frequency of stimulation (high versus low). The mechanism underlying tES is a change in neuronal membrane potentials that appears to be dependent mainly on the direction of current flow (anodal versus cathodal). Nevertheless, the final effects induced by TMS or tES depend on many technical parameters used during stimulation, such as the intensity of stimulation, coil orientation, site of the reference electrode, and time of application. Moreover, an important factor is the possible interactions between these factors and the physiological and cognitive state of the subject. To use NIBS in cognition, it is important to understand not only how NIBS functions but also the brain mechanisms being studied and the features of the area of interest. To describe better the advanced knowledge provided by NIBS in cognition, we will treat each NIBS technique separately and underline the related hypotheses beyond applications.

Non-invasive brain stimulation (NIBS) is a method for the study of cognitive function that is quickly gaining popularity. It bypasses the correlative approaches of other imaging techniques, making it possible to establish a causal relationship between cognitive processes and the functioning of specific brain areas. Like lesion studies, NIBS can provide information about where a particular process occurs. However, NIBS offers the opportunity to study brain mechanisms beyond process localisation, providing information about when activity in a given brain region is involved in a cognitive process, and even how it is involved. When using NIBS to explore cognitive processes, it is important to understand not only how NIBS functions but also the functioning of the neural structures themselves. We know that NIBS techniques have the potential to transiently influence behaviour by altering neuronal activity, which may have facilitatory or inhibitory behavioural effects, and these alterations can be used to understand how the brain works. Given that NIBS necessarily involves the relatively indiscriminate activation of large numbers of neurons, its impact on a neural system can be easily understood as modulation of neural activity that changes the relation between noise and signal. In this review, we describe the mutual interactions between NIBS and brain activity and provide an updated and precise perspective on the theoretical frameworks of NIBS and their impact on cognitive neuroscience. By transitioning our discussion from one aspect (NIBS) to the other (cognition), we aim to provide insights to guide future research.

Transcranial alternating current stimulation (tACS) is a promising tool for modulating brain oscillations, as well as a possible/ntherapeutic intervention. However, the lack of conclusive evidence on whether tACS is able to effectively affect cortical/nactivity continues to limit its application. The present study aims to address this issue by exploiting the well-known/ninhibitory alpha rhythm in the posterior parietal cortex during visual perception and attention orientation. Four groups of/nhealthy volunteers were tested with a Gabor patch detection and discrimination task. All participants were tested at the/nbaseline and selective frequencies of tACS, including Sham, 6 Hz, 10 Hz, and 25 Hz. Stimulation at 6 Hz and 10 Hz over the/noccipito-parietal area impaired performance in the detection task compared to the baseline. The lack of a retinotopically/norganised effect and marginal frequency-specificity modulation in the detection task force us to be cautious about the/neffectiveness of tACS in modulating brain oscillations. Therefore, the present study does not provide significant evidence for/ntACS reliably inducing direct modulations of brain oscillations that can influence performance in a visual task.

Noninvasive brain stimulation (NIBS) is a unique method for studying cognitive function. For the study of cognition, NIBS has gained popularity as a complementary method to functional neuroimaging. By bypassing the correlative approaches of standard imaging techniques, it is possible to establish a putative relationship between brain cognition. In fact, functional neuroimaging data cannot demonstrate the actual role of a particular cortical activation in a specific function because an activated area may simply be correlated with task performance, rather than being responsible for it. NIBS can induce a temporary modification of performance only if the stimulated area is causally engaged in the task. In analogy with lesion studies, NIBS can provide information about where and when a particular process occurs. Based on this assumption, NIBS has been used in many different cognitive domains. However, one of the most interesting questions in neuroscience may not be where and when, but how cognitive activity occurs. Beyond localization approaches, NIBS can be employed to study brain mechanisms. NIBS techniques have the potential to influence behavior transiently by altering neuronal activity, which may have facilitatory or inhibitory behavioral effects. NIBS techniques include transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). TMS has been shown transiently to modulate neural excitability in a manner that is dependent mainly on the timing and frequency of stimulation (high versus low). The mechanism underlying tES is a change in neuronal membrane potentials that appears to be dependent mainly on the direction of current flow (anodal versus cathodal). Nevertheless, the final effects induced by TMS or tES depend on many technical parameters used during stimulation, such as the intensity of stimulation, coil orientation, site of the reference electrode, and time of application. Moreover, an important factor is the possible interactions between these factors and the physiological and cognitive state of the subject. To use NIBS in cognition, it is important to understand not only how NIBS functions but also the brain mechanisms being studied and the features of the area of interest. To describe better the advanced knowledge provided by NIBS in cognition, we will treat each NIBS technique separately and underline the related hypotheses beyond applications.

Physiological aging affects early sensory-perceptual processes. The aim of this experiment was to evaluate changes in auditory sensory memory in physiological aging using the Mismatch Negativity (MMN) paradigm as index. The MMN is a marker recorded through the electroencephalogram and is used to evaluate the integrity of the memory system. We adopted a new, faster paradigm to look for differences between 3 groups of subjects of different ages (young, middle age and older adults) as a function of short or long intervals between stimuli. We found that older adults did not show MMN at long interval condition and that the duration of MMN varied according to the participants' age. The current study provides electrophysiological evidence supporting the theory that the encoding of stimuli is preserved during normal aging, whereas the maintenance of sensory memory is impaired. Considering the advantage offered by the MMN paradigm used here, these data might be a useful reference point for the assessment of auditory sensory memory in pathological aging (e.g., in neurodegenerative diseases).

To calibrate the intensity of transcranial magnetic stimulation (TMS) at the occipital pole, the phosphene threshold is used as a measure of cortical excitability. The phosphene threshold (PT) refers to the intensity of magnetic stimulation that induces illusory flashes of light (phosphenes) on a proportion of trials. The existing PT estimation procedures lack the accuracy and mathematical rigour of modern threshold estimation methods. We present an improved and automatic procedure for estimating the PT which is based on the well-established Ψ Bayesian adaptive staircase approach. To validate the new procedure, we compared it with another commonly used procedure for estimating the PT. We found that our procedure is more accurate, reliable, and rapid when compared with an existing PT measurement procedure. The new procedure is implemented in Matlab and works automatically with the Magstim Rapid(2) stimulator using a convenient graphical user interface. The Matlab program is freely available for download.

The underlying mechanisms of action of transcranial magnetic stimulation (TMS) are still a matter of debate. TMS may impair a subject's performance by increasing neural noise, suppressing the neural signal, or both. Here, we delivered a single pulse of TMS (spTMS) to V5/MT during a motion direction discrimination task while concurrently manipulating the level of noise in the motion stimulus. Our results indicate that spTMS essentially acts by suppressing the strength of the relevant visual signal. We suggest that TMS may induce a pattern of neural activity that complements the ongoing activation elicited by the sensory signal in a manner that partially impoverishes that signal.

The aim of this study was to test the role of the visual primary (V1) and the middle temporal area (V5/MT) in the illusory motion perception evoked by the Enigma figure. The Enigma figure induces a visual illusion that is characterized by apparent rotatory motion in the presence of a static figure. By means of repetitive transcranial magnetic stimulation (rTMS) we show that V5/MT is causally linked to the illusory perception of motion. When rTMS was applied bilaterally over V5/MT just prior to presentation of the Enigma figure, the perception of illusory motion was disrupted for approximately 400. ms resulting in a delayed illusion onset. In contrast, rTMS applied over V1 did not have any effect on the illusory perception of motion. These results show that V5/MT, a visual cortical area associated with real motion perception, is also important for the perception of illusory motion, while V1 appears not to be functionally involved in illusory motion perception. © 2011 Elsevier Ltd.

Transcranial magnetic stimulation (TMS) is a technique used to study perceptual, motor, and cognitive functions in the human brain. Its effects have been likened to a “virtual brain lesion,” but a direct test of this assumption is lacking. To verify this hypothesis, we measured psychophysically the interaction between the neural activity induced by a visual motion-direction discrimination task and that induced by TMS. The visual stimulus featured two elements: a visual signal (dots that moved coherently in one direction) and visual noise (dots that moved randomly in many directions). Three hypotheses were tested to explain the impairment in performance as a result of TMS: 1) a decrease in signal strength; 2) an induction of randomly distributed neural noise with an accompanying decrement in system sensitivity; and 3) a suppression of relevant information processing and addition of neural noise. We provide evidence in favor of the second hypothesis by showing that TMS basically acts by adding neural noise to the perceptual process.

Carlo Miniussi*, Manuela Ruzzoli and Vincent Walsh Department of Biomedical Sciences and Biotechnology, National Institute of Neuroscience, University of Brescia, Italy Cognitive Neuroscience Section, IRCCS San Giovanni di Dio Fatebenefratelli, Brescia, Italy Department of Neurological and Vision Sciences, University of Verona, Italy Institute of Cognitive Neuroscience and Department of Psychology, University College London, UK

Question It is widely recognized that oscillatory activity plays an important functional role in neural systems. Decreases in alpha (∼10Hz) EEG/MEG activity in the parietal cortex correlate with the deployment of spatial attention controlateral to target location in visual, auditory and tactile domains (Bauer et al., 2012; Foxe and Snyder, 2011; Linkenkaer-Hansen et al., 2004). Recently, repetitive Transcranial Magnetic Stimulation (rTMS) has been successfully applied to entrain a specific frequency at the parietal cortex (IPS) and the visual cortex. A short burst of 10Hz rTMS impaired contralateral visual target detection and improved it ipsilaterally, compared to other control frequencies (Romei et al., 2010). This finding suggests a causal role of rhythmic activity in the alfa range in perception (Thut et al., 2011). The aim of the present study is to address whether entraining alpha frequency in the IPS plays a role in tactile orienting, indicating similarities between senses (vision and touch) in the communication between top-down (parietal) and primary sensory areas (V1 or S1). Methods We applied rhythmic TMS at 10Hz and 20Hz to the (right or left) IPS and S1, immediately before a masked vibrotactile target stimulus (present in 50% of the trials) to the left or right hand. Results Preliminary results lean towards the consequential effects of entraining alpha frequency into IPS for tactile detection such that it decreases tactile perception contralaterally and increases it ipsilaterally, compared to Sham. Conclusions The results suggest the existence of a similar mechanism of orienting attention in vision and touch, therefore paving the way for further testing the role of parietal alpha band oscillation in other tactile information processing, such as in tactile remapping, a mechanism that allow our brain to localize tactile events in external space. Acknowledgment European Research Council (StG-2010 263145).

Non-invasive brain stimulation (NIBS) is a unique method to study cognitive functions. NIBS offers the opportunity to study brain mechanisms beyond process localisation, providing information about when activity in a given brain region is involved in a cognitive process, and even how it is involved. We know that NIBS techniques have the potential to transiently influence behaviour by altering neuronal activity, which may have facilitatory or inhibitory behavioural effects, and these alterations can be used to understand how the brain works. NIBS techniques include transcranial magnetic and electric stimulation (TMS and tES). The mechanisms underlying TMS and tES seem to be different, nevertheless, the final behavioural effects induced by TMS and tES are often very similar. In this presentation I will describe the mutual interactions between NIBS and brain activity and provide an updated perspective on the theoretical frameworks of NIBS and their impact on cognitive neuroscience. Given that NIBS necessarily involves the relatively indiscriminate activation of large numbers of neurons, its impact on a neural system can be easily understood as modulation of neural activity that changes the relation between noise and signal. The framework that I wish to proposed here offers the opportunity to understand how NIBS, by altering levels of noise, could usually impair, but sometimes improve performance on a task. Depending on the amount of noise introduced by NIBS, the existing level of noise in the system or in the task due to the state of the subject, it is possible to evaluate the final result. By transitioning the discussion from one aspect (NIBS) to the other (cognition), the aim is to provide insights to guide future research.

It has been claimed that oscillatory firing activity plays a functional role in neural systems. Evidence suggests that rhythmic activity in the alpha range (∼10 Hz) has a causal effect in visual perception and attention deployment (Romei et al., 2008). The present study addresses the causal role of brain rhythms in tactile processing. We used rhythmic TMS to entrain specific frequencies (10 and 20 Hz) focusing on the parietal lobe (IPS) and primary somatosensory areas (S1). The results revealed that entrainment of alpha frequency in the IPS decreases contralateral somatosensory detection and enhances ipsilateral performance [experiment 1]. Interestingly, we found that this TMS-induced ipsilateral enhancement effect abides with an external frame of reference, not to the anatomical side [experiment 2]. Furthermore, the effect of pre-stimulus entrainment of 10 and 20 Hz activity in S1 is not univocal when arrhythmic TMS is engaged [experiment 3]. Altogether, the present findings suggest that the functional role in tactile processing of alpha frequency in IPS is specific to the interaction with the external world, indicating similarities between senses (vision and touch) in the communication between top-down (parietal) and primary sensory areas (V1 or S1). Pre-stimulus S1 rTMS might affect performance regardless of the frequency engaged, that is, when the stimulus is absent (pre-stimulus) TMS decreases cortical excitability in S1.

Predicting an upcoming event in time or modality leads to expectancy-based benefits for the predicted time point or modality and to costs for the unpredicted ones. Yet, it is not clear how expectancy to an event in time interacts with expectancy of a particular modality. In our study, participants had to perform a discrimination task (single or double pulse) on visual or tactile targets. An auditory cue (75% of validity) was used to increase expectancy in one or the other modality. We also manipulated the time point (1 or 3 s after the cue) in which the stimulus appeared in a probabilistic way. We found that increasing the temporal expectation reduced the reaction time of valid targets in both, vision and touch, but when the target was presented in the unexpected modality (invalid cue) time predictability induced a cost in reaction time. Therefore the benefit of time expectancy is converted into a cost if the stimulus is presented in the unattended modality, suggesting cross-modal competition in the temporal domain.

Evidence suggests that Alzheimer's disease (AD) is part of a continuum, characterized by long preclinical phases before the onset of clinical symptoms. In several cases, this continuum starts with a syndrome, defined as mild cognitive impairment (MCI), in which daily activities are preserved despite the presence of cognitive decline. The possibility of having a reliable and sensitive neurophysiological marker that can be used for early detection of AD is extremely valuable because of the incidence of this type of dementia. In this study, we aimed to investigate the reliability of auditory mismatch negativity (aMMN) as a marker of cognitive decline from normal ageing progressing from MCI to AD. We compared aMMN elicited in the frontal and temporal locations by duration deviant sounds in short (400 ms) and long (4000 ms) inter-trial intervals (ITI) in three groups. We found that at a short ITI, MCI showed only the temporal component of aMMN and AD the frontal component compared to healthy elderly who presented both. At a longer ITI, aMMN was elicited only in normal ageing subjects at the temporal locations. Our study provides empirical evidence for the possibility to adopt aMMN as an index for assessing cognitive decline in pathological ageing. This research was supported by a Project grant from Cariplo Foundation and RC “Ministero della Salute”. M.R. was supported by Juan de la Cierva postdoctoral fellowship (JCI-2012–12335) from the Spanish Government.

In this study we assessed changes in phosphene perception and transcranial magnetic stimulation (TMS)-evoked potentials (TEPs) after light and dark adaptation. The primary aim was to link a direct neurophysiological correlate of cortical excitability (i.e., TEPs) to the subjective report (i.e., phosphene perception) in order to evaluate whether environmental light changing induced modifications in visual cortex excitability or only at retinal level, as previously reported. Ten young healthy participants underwent three conditions: baseline (environmental light), 30 minutes of light adaptation (LA) and 30 minutes of and dark adaptation (DA) in counterbalanced order. After each condition, we assessed the TMS-induced phosphenes perception by single pulse TMS over the visual cortex (V1) while 32-channels electroencephalogram (EEG) was recorded. Coil position was maintained stable across conditions through a stereotaxic neuronavigation system. Phosphenes threshold was calculated through the method of constant stimuli, in which TMS pulses were delivered at different TMS intensities ranging from 46 to 76% of the maximal stimulator output. The participants were asked to report whether they perceived or not a phosphene after each TMS pulse. A Weibull function was fitted to phosphenes report for each condition and participant separately, in order to estimate the threshold and slope of the psychometric functions. Results confirmed that dark adaptation modulated visual perception: the slope of the psychometric function after dark adaptation significantly increased (p

The representation of spatial information related to an event can influence behavior even when location is task-irrelevant, as in the case of Stimulus–Response (S-R) compatibility effects on the Simon task. However, unlike single-modality situations, which are often used to study the Simon effect, in real-life scenarios various sensory modalities provide spatial information coded in different coordinate systems. Here, we address the expression of S-R compatibility effects in mixed-modality contexts, where events can occur in 1 of various sensory modalities (i.e., vision, touch or audition). The results confirm that, in single-modality cases, Simon effects in vision are expressed in an external spatial frame of reference, while touch information is coded anatomically. Remarkably, when mixing visual and tactile trials in an unpredictable way, the Simon effect disappeared in vision whereas tactile Simon effects remained expressed in their own (anatomical) frame of reference. Mixing visual and auditory stimuli did not obliterate the visual Simon effect and S-R compatibility effects in an external reference frame were evident for both modalities. The extinction of visual Simon effects as a result of mixing visual and tactile modalities can be interpreted as a consequence of the dynamic reorganization of the weights associated to the different sources of spatial information at play. This research was supported by the Ministerio de Economia y Competitividad (PSI2016-75558-P), the AGAUR Generalitat de Catalunya (2014SGR856) and the European Research Council (StG-2010 263145) to SSF. M.R. was supported by the Juan de la Cierva postdoctoral fellowship (JCI-2012-12335) from the Ministerio de Economia y Competitividad.