Differential modulation of the N2 and P3 event-related potentials by response conflict and inhibition

Background: Developing reliable and specific neural markers of cognitive processes is essential to improve understanding of healthy and atypical brain function. Despite extensive research there remains uncertainty as to whether two electrophysiological markers of cognitive control, the N2 and P3, are better conceptualised as markers of response inhibition or response conflict. The present study aimed to directly compare the effects of response inhibition and response conflict on the N2 and P3 event-related potentials, within-subjects. Method: A novel hybrid go/no-go flanker task was performed by 19 healthy adults aged 18 to 25 years while EEG data were collected. The response congruence of a central target stimulus and 4 flanking stimuli was manipulated between trials to vary the degree of response conflict. Response inhibition was required on a proportion of trials. N2 amplitude was measured at two frontal electrode sites; P3 amplitude was measured at 4 midline electrode sites. Results: N2 amplitude was greater on incongruent than congruent trials but was not enhanced by response inhibition when the stimulus array was congruent. P3 amplitude was greater on trials requiring response inhibition; this effect was more pronounced at frontal electrodes. P3 amplitude was also enhanced on incongruent compared with congruent trials. Discussion: The findings support a role for N2 amplitude as a marker of response conflict and for the frontal shift of the P3 as a marker of response inhibition. This paradigm could be applied to clinical groups to help clarify the precise nature of impaired action control in disorders such as attention deficit/hyperactivity disorders (ADHD)

Monetary reward and punishment to response inhibition modulate activation and synchronization within the inhibitory brain network

© 2018 Chikara, Chang, Lu, Lin, Lin and Ko. A reward or punishment can modulate motivation and emotions, which in turn affect cognitive processing. The present simultaneous functional magnetic resonance imaging-electroencephalography study examines neural mechanisms of response inhibition under the influence of a monetary reward or punishment by implementing a modified stop-signal task in a virtual battlefield scenario. The participants were instructed to play as snipers who open fire at a terrorist target but withhold shooting in the presence of a hostage. The participants performed the task under three different feedback conditions in counterbalanced order: a reward condition where each successfully withheld response added a bonus (i.e., positive feedback) to the startup credit, a punishment condition where each failure in stopping deduced a penalty (i.e., negative feedback), and a no-feedback condition where response outcome had no consequences and served as a control setting. Behaviorally both reward and punishment conditions led to significantly down-regulated inhibitory function in terms of the critical stop-signal delay. As for the neuroimaging results, increased activities were found for the no-feedback condition in regions previously reported to be associated with response inhibition, including the right inferior frontal gyrus and the pre-supplementary motor area. Moreover, higher activation of the lingual gyrus, posterior cingulate gyrus (PCG) and inferior parietal lobule were found in the reward condition, while stronger activation of the precuneus gyrus was found in the punishment condition. The positive feedback was also associated with stronger changes of delta, theta, and alpha synchronization in the PCG than were the negative or no-feedback conditions. These findings depicted the intertwining relationship between response inhibition and motivation networks

A review on the electroencephalography markers of Stroop executive control processes

The present article on executive control addresses the issue of the locus of the Stroop effect by examining neurophysiological components marking conflict monitoring, interference suppression, and conflict resolution. Our goal was to provide an overview of a series of determining neurophysiological findings including neural source reconstruction data on distinct executive control processes and sub-processes involved in the Stroop task. Consistently, a fronto-central N2 component is found to reflect conflict monitoring processes, with its main neural generator being the anterior cingulate cortex (ACC). Then, for cognitive control tasks that involve a linguistic component like the Stroop task, the N2 is followed by a centro-posterior N400 and subsequently a late sustained potential (LSP). The N400 is mainly generated by the ACC and the prefrontal cortex (PFC) and is thought to reflect interference suppression, whereas the LSP plausibly reflects conflict resolution processes. The present overview shows that ERP constitute a reliable methodological tool for tracing with precision the time course of different executive processes and sub-processes involved in experimental tasks involving a cognitive conflict. Future research should shed light on the fine-grained mechanisms of control respectively involved in linguistic and non-linguistic tasks

Event-Related Potential Correlates of Performance-Monitoring in a Lateralized Time-Estimation Task

Performance-monitoring as a key function of cognitive control covers a wide range of diverse processes to enable goal directed behavior and to avoid maladjustments. Several event-related brain potentials (ERP) are associated with performance-monitoring, but their conceptual background differs. For example, the feedback-related negativity (FRN) is associated with unexpected performance feedback and might serve as a teaching signal for adaptational processes, whereas the error-related negativity (ERN) is associated with error commission and subsequent behavioral adaptation. The N2 is visible in the EEG when the participant successfully inhibits a response following a cue and thereby adapts to a given stop-signal. Here, we present an innovative paradigm to concurrently study these different performance-monitoring-related ERPs. In 24 participants a tactile time-estimation task interspersed with infrequent stop-signal trials reliably elicited all three ERPs. Sensory input and motor output were completely lateralized, in order to estimate any hemispheric processing preferences for the different aspects of performance monitoring associated with these ERPs. In accordance with the literature our data suggest augmented inhibitory capabilities in the right hemisphere given that stop-trial performance was significantly better with left- as compared to right-hand stop-signals. In line with this, the N2 scalp distribution was generally shifted to the right in addition to an ipsilateral shift in relation to the response hand. Other than that, task lateralization affected neither behavior related to error and feedback processing nor ERN or FRN. Comparing the ERP topographies using the Global Map Dissimilarity index, a large topographic overlap was found between all considered components.With an evenly distributed set of trials and a split-half reliability for all ERP components ≥.85 the task is well suited to efficiently study N2, ERN, and FRN concurrently which might prove useful for group comparisons, especially in clinical populations

Thoughts on Neurophysiological Signal Analysis and Classification

Neurophysiological signal is crucial intermediary, through which brain activity can be quantitatively measured and brain mechanisms are able to be revealed. In particular, those non-invasive neurophysiological signals, such as electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI), are welcome and frequently utilised in a variety of studies because those signals can be non-invasively recorded without harms to the human brain while they are conveying abundant information pertaining to brain activity. The recorded neurophysiological signals are analysed to mine meaningful information for the understanding of brain mechanisms or are classified to distinguish different patterns (e.g., different cognitive states, brain diseases versus healthy controls). To date, remarkable progress has been made in both the analysis and classification of neurophysiological signal, but scholars are not feeling complacent. Consistent effort ought to be paid to advance the research of analysis and classification based on neurophysiological signal. In this paper, I express my thoughts about promising future directions in neurophysiological signal analysis and classification based on the current developments and achievements. I will elucidate the thoughts after brief summaries of relevant backgrounds, achievements, and tendencies. According to my personal selection and preference, I mainly focus on brain connectivity, multidimensional array (tensor), multi-modality, multiple task classification, deep learning, big data, and naturalistic experiment. Hopefully, my thoughts could give a little help to inspire new ideas and contribute to the research of analysis and classification of neurophysiological signal in some way

Emotional enhancement of error detection : the role of perceptual processing and inhibition monitoring in failed auditory stop trials

The first aim of the present study was to test whether arousing, aversive sounds can influence inhibitory task performance and lead to increased error monitoring relative to a neutral task condition. The second aim was to examine whether the enhancement of error monitoring in an affective context (if present) could be predicted from stop-signal-related brain activity. Participants performed an emotional stop-signal task that required response inhibition to aversive and neutral auditory stimuli. The behavioral data revealed that unpleasant sounds facilitated inhibitory processing by decreasing the stop-signal reaction time and increasing the inhibitory rate relative to neutral tones. Aversive sounds evoked larger N1, P3, and Pe components, indicating improvements in perceptual processing, inhibition, and conscious error monitoring. A first regression analysis, conducted regardless of the category of the stop signal, revealed that both selected indexes of stop-signal-related brain activity - the N1 and P3 amplitudes recorded in the unsuccessfully inhibited trials - significantly accounted for the Pe component variance, explaining a large amount of the observed variation (66%). A second regression model, focused on difference measures (emotional minus neutral), revealed that the affective increase in the P3 amplitude on failed stop trials was the only factor that significantly accounted for the emotional enhancement effect in the Pe amplitude. This suggests that, in general (regardless of stop - signal condition), error processing is stronger if the erroneous response directly follows the stimulus, which was effectively processed on both the perceptual and action - monitoring levels. However, only inhibition - monitoring evidence accounts for the emotional increase in conscious error detection

Integration of EEG-FMRI in an Auditory Oddball Paradigm Using Joint Independent Component Analysis

The integration of event-related potential (ERP) and functional magnetic resonance imaging (fMRI) can contribute to characterizing neural networks with high temporal and spatial resolution. The overall objective of this dissertation is to determine the sensitivity and limitations of joint independent component analysis (jICA) within-subject for integration of ERP and fMRI data collected simultaneously in a parametric auditory oddball paradigm. The main experimental finding in this work is that jICA revealed significantly stronger and more extensive activity in brain regions associated with the auditory P300 ERP than a P300 linear regression analysis, both at the group level and within-subject. The results suggest that, with the incorporation of spatial and temporal information from both imaging modalities, jICA is more sensitive to neural sources commonly observed with ERP and fMRI compared to a linear regression analysis. Furthermore, computational simulations suggest that jICA can extract linear and nonlinear relationships between ERP and fMRI signals, as well as uncoupled sources (i.e., sources with a signal in only one imaging modality). These features of jICA can be important for assessing disease states in which the relationship between the ERP and fMRI signals is unknown, as well as pathological conditions causing neurovascular uncoupling, such as stroke

When smaller is more – investigating the interplay between continuous sensory cues and numerical information

Research on numerical cognition is not limited to symbolic numbers and mathematics but it also includes discrete and continuous magnitudes. Continuous magnitudes are ubiquitous in nature and serve as important cues in everyday life situations. When one tries to choose the plate with more cookies in the cafeteria, they usually do not count the cookies but rather arrive at a fair estimate by comparing such continuous magnitudes. For example, nine cookies on a plate will occupy a larger area and have to be placed denser to each other than five cookies. Recent research has shown that, as opposed to the classical view, the processing of symbolic numbers and non-symbolic numerosities is not independent from such sensory cues. The present dissertation consists of two studies that investigate what psychological processes underlie the interaction between sensory cues and numerical information. Study 1 aimed to replicate and extend the findings of Gebuis & Reynvoet who systematically manipulated the relationship between continuous and discrete magnitudes in a non-symbolic numerical comparison task. The main goal was to assess the stability and the robustness of the influence of sensory cues on numerical comparisons as the originally reported patterns suggest a complex interaction between these two kinds of information that are difficult to reconcile with the classic views on numerical processing. Indeed, the results confirmed that continuous magnitudes have a complex effect on numerical judgements and that their interaction can be either due to incomplete inhibition or due to integration of continuous magnitudes during numerical tasks. Study 2 turned to symbolic numbers and investigated whether inhibition underlies the interaction of continuous sensory properties and numerical information. To this end a novel paradigm was introduced that allowed to investigate well-established electrophysiological correlates of inhibition with numerical stimuli. The results provide evidence that inhibition underlies the interaction between sensory cues and numerical information. Additionally, they show that the paradigm introduced in Study 2 may suitable to investigate these processes across different developmental stages and numeracy levels

Measuring neural mechanisms of error processing with fMRI: model-based and data-driven methods

Vaikka virheenkäsittely on eräs tärkeimmistä kognitiivisista toiminnoista, on vielä epäselvää, käsittelevätkö ihmisaivot itse tehtyjä ja havaittuja toisten tekemiä virheitä samalla tavalla. Tässä tutkimuksessa tutkittiin toiminnallisella magneettikuvauksella (fMRI) mekanismeja, jotka liittyvät itse tehtyjen virheiden ja sekä kontrolloiduissa että luonnollisissa tilanteissa havaittujen virheiden käsittelyyn. Ensimmäisessä koeasetelmassa koehenkilöt pelasivat yksinkertaista peliä tehden välillä virheitä. Toisessa kokeessa katseltiin videota kyseisestä pelistä toisen pelaajan pelaamana. Kolmannessa kokeessa katseltiin lyhyitä videopätkiä erilaisista arkielämän virhetilanteista. fMRI-dataa analysoitiin yleisellä lineaarisella mallilla (GLM) ja riippumattomien komponenttien analyysilla (ICA) virhesidonnaisen aivotoiminnan ja toiminnallisen konnektiivisuuden selvittämiseksi. Luonnollisten virheiden ennakoinnin aiheuttamaa aivoaktivaatiota tutkittiin myös erikseen. Lisäksi laskettiin virheiden aiheuttamat hemodynaamiset vasteet 23:lla eri aivoalueella ja tutkittiin eri alueiden vasteiden välisiä korrelaatioita sekä eri koetilanteiden aiheuttamien vasteiden eroja. Itse tehdyt ja luonnolliset havaitut virheet aiheuttivat samanlaista aktivaatiota aivojuovion osa-alueilla (häntätumake ja linssitumakkeen pallo) sekä rostraalisen etummaisen pihtipoimun ja näköaivokuoren alueilla. Dorsaalinen etummainen pihtipoimu, alempi otsalohkon poimu ja aivosaari aktivoituivat samalla tavoin itse tehtyjen virheiden ja luonnollisten virheiden ennakoinnin aikana. Sen sijaan havaitut virheet pelissä eivät aiheuttaneet merkittäviä vasteita. Sekä ICA-tuloksien että yksittäisten aivoalueiden vasteiden korrelaatioiden perusteella virheiden aikana aktivoituneet alueet olivat toiminnallisesti yhteydessä keskenään. Nämä löydökset vahvistavat teorioita rostraalisen ja dorsaalisen etummaisen pihtipoimun erillisistä toiminnoista virheenkäsittelyn aikana ja viittaavat siihen että aivojuovio käsittelee melko samalla tavoin itse tehtyjä ja havaittuja virheitä.Even though processing of errors is one of the most fundamental cognitive functions, it is still unclear whether the human brain processes self-generated and observed errors similarly. In this study, we examined the neural mechanisms of error processing with functional magnetic resonance imaging (fMRI) during self-committed errors, as well as observed errors made by others in both controlled and naturalistic situations. In the first experiment the subjects played a simple response selection game, occasionally making errors. In the second experiment they watched a video recording of the same game played by someone else. In the third experiment they watched short video clips depicting other people failing in everyday situations. The fMRI data were analyzed with the general linear model (GLM) and independent component analysis (ICA) in order to detect error-related activation and functional connectivity. With the third task we also examined the activity caused by error anticipation. In addition, correlations between error-related BOLD responses in 23 predefined regions of interest (ROI) were calculated, and the regional responses in different experimental conditions were compared. Similar activations were detected during self-committed and observed naturalistic errors in striatal subregions (caudate nucleus and globus pallidus), rostral anterior cingulate cortex (ACC) and visual cortical regions. Dorsal ACC, inferior frontal gyrus and insula showed similar activation during self-committed errors and anticipation of naturalistic observed errors. Observed errors in the game could not produce a robust BOLD response. Both ICA and ROI-based analyses indicated high functional connectivity between the key regions of the error monitoring circuit. Together, these findings support the theories advocating distinct functions of rostral and dorsal ACC in error monitoring and suggest that the striatum processes self-generated and observed errors quite similarly