Frontal Negativity Research Articles

Word meaning acquisition is reflected in brain potentials of isolated words

Learning a new concept and corresponding word typically involves repeated exposure to the word in the same or a similar context until the link crystallizes in long term memory. Although electrophysiological indices of the result of learning are well documented, there is currently no measure of the process of conceptually-mediated learning itself. Here, we recorded event-related brain potentials from participants who read unfamiliar words presented in isolation followed by a definition that either explained the meaning of the word or was a true, but uninformative statement. Self-reported word knowledge ratings increased for those words that were followed by meaningful definitions and were correlated with a decrease in ERP amplitude of a late frontal negativity (LFN) elicited by the isolated word. Importantly, the rate of LFN amplitude change predicted post-hoc learning outcome measures. Therefore, the LFN is real-time measure that is not under conscious control and which reflects conceptually-mediated learning. We propose that the LFN provides for the first time the opportunity to assess learning during study.

Cathodal high-definition transcranial direct current stimulation (HD-tDCS) over the dorsomedial prefrontal cortex increases frontal related negativity amplitude during reversal learning

Cathodal high-definition transcranial direct current stimulation (HD-tDCS) over the dorsomedial prefrontal cortex increases frontal related negativity amplitude during reversal learning

Flexible conceptual combination: Electrophysiological correlates and consequences for associative memory

When meaningful stimuli such as words are encountered in groups or pairs (e.g., "elephant-ferry"), they can be processed either separately or as an integrated concept ("an elephant ferry"). Prior research suggests that memory for integrated associations is supported by different mechanisms than is memory for nonintegrated associations. However, little is known about the neurocognitive mechanisms that support the integration of novel stimulus pairs. We recorded ERPs while participants memorized sequentially presented, unrelated noun pairs using a strategy that either did or did not involve attempting to construct coherent definitions. We varied the concreteness of the first noun in each pair to examine whether conceptual combination instructions would induce compositional concreteness effects, or differences in ERPs evoked by the second noun as a function of the concreteness of the first noun. We found that the conceptual combination task, but not the noncombinatory encoding task, produced compositional concreteness effects on a late frontal negativity previously linked to visual imagery. Moreover, word pairs studied under conceptual combination instructions showed evidence of more unitized or holistic memory representations on associative recognition and free recall tests. Finally, item analyses indicated that (a) items with higher normed imageability ratings were rated by participants as easier to conceptually combine, and (b) in the conceptual combination task, ease-of-combination ratings mediated an indirect relationship between imageability and subsequent associative memory. These data are suggestive of a role of compositional imagery in the online formation of novel concepts via conceptual combination.

The impact of emotion intensity on recognition memory: Valence polarity matters

Although the effects of emotion of different emotional intensity on memory have been investigated, it remain unclear whether the influence of emotional intensity on memory varies depending on the stimulus valence polarity (i.e., positive or negative). To address this, event-related potentials were recorded when subjects performed a continuous old/new discrimination task, for highly negative (HN), mildly negative (MN) and neutral pictures in the negative session; and for highly positive (HP), mildly positive (MP) and neutral pictures in the positive session. The results showed that relative to neutral stimuli, both HN and MN stimuli showed increased memory discrimination scores, and enhanced old/new effect in early FN400 (Frontal Negativity), but not late positive component (LPC) amplitudes. By contrast, relative to MP stimuli, HP and neutral stimuli showed increased memory discrimination scores and enhanced old/new effect in LPC but not FN400 amplitudes. Additionally, we observed a significant positive correlation between the memory discrimination score and the old/new effect in the amplitudes of the FN400 and LPC, respectively. These results indicate that both HN and MN stimuli were remembered better than neutral stimuli; whereas the recognition was worse for MP stimuli than Neutral and HP stimuli. In conclusion, in the present study, we observed that the effect of emotion intensity on memory depends on the stimulus valence polarity.

Foreign-accented speaker identity affects neural correlates of language comprehension

Abstract This study tested semantic and grammatical processing of native- and foreign-accented speech. Monolinguals with little experience with foreign-accented speech listened to sentences spoken by foreign-accented and native-accented speakers while their brain activity was recorded using EEG/ERPs. We gathered behavioral measures of sentence comprehension, language attitudes, and accent perception. Behavioral results showed that listeners were highly accurate in comprehending both native- and foreign-accented sentences. ERP results showed that grammatical and semantic violations elicited different neural responses in native versus foreign accented speech. Native-accented speech elicited a frontal negativity (Nref) for grammatical violations and a robust N400 for semantic violations. However, in foreign-accented speech only semantic (not grammatical) violations elicited an ERP effect, a late negativity. Closer inspection of listeners who did and who did not correctly identify the foreign accent revealed that listeners who identified the foreign accent showed ERP responses for both grammatical and semantic errors: an N400-like effect to grammatical errors and a late negativity to semantic errors. In contrast, listeners who did not correctly identify the foreign accent showed no ERP responses to grammatical errors in the foreign-accented condition, but did show a late negativity to semantic errors. These findings provide novel insights into understanding the effects of listener experience and foreign-accented speaker identity on the neural correlates of language processing.

ERP correlates of the conflict level in the multi-response Stroop task

This EEG study (N=33) examined event-related potentials associated with conflict between activated responses in the Stroop task, in order to examine the conflict monitoring theory of cognitive control, which predicts the strength of exerted control to be proportional to the detected level of conflict. However, existing research manipulated the sole presence/absence of conflict, but not its exact level. Here, by using a modified color-word task that allowed multiple correct responses for target colors, as well as multiple incorrect responses for distractor words, we manipulated the level of conflict among activated responses (and not only its presence). We expected that a larger number of activated incorrect responses (i.e., a presumably higher conflict) would entail more pronounced conflict-related potentials. Indeed, two components of the N450 wave, parietal negativity and medial frontal negativity, were more negatively deflected when conflict was higher, than when it was lower, visibly responding to the level of conflict. Slow potential weakly responded to the sheer presence of conflict, but not to its level. These results can be plausibly explained by the conflict monitoring theory with a modified conflict evaluation formula, whereas they are at odds with several alternative theories of cognitive control.

Frontal negativity: An electrophysiological index of interpersonal guilt

ABSTRACTThe present study aimed to reveal the temporal course and electrophysiological correlates of interpersonal guilt. Human participants were asked to perform multiple rounds of a dot-estimation task with their partners, while event-related potential being recorded. The paired participants were informed that they would win money if both responded correctly; otherwise, both of them would lose money. The feeling of guilt in Self-Wrong condition (SW) was significantly higher than that in Both-Wrong and Partner-Wrong conditions. At approximately 350 ms after the onset of feedback presentation, greater negativities were observed in the frontal regions in the guilt condition (i.e., SW) than those in the non-guilt condition. The guilt-modulated frontal negativity might reflect the interactions of self-reflection, condemnation, and negative emotion.

Individual Differences in Brain Responses to Dynamic Facial Expressions and their Relationship to Face Cognition Abilities

This EEG study (N=33) examined event-related potentials associated with conflict between activated responses in the Stroop task, in order to examine the conflict monitoring theory of cognitive control, which predicts the strength of exerted control to be proportional to the detected level of conflict. However, existing research manipulated the sole presence/absence of conflict, but not its exact level. Here, by using a modified color-word task that allowed multiple correct responses for target colors, as well as multiple incorrect responses for distractor words, we manipulated the level of conflict among activated responses (and not only its presence). We expected that a larger number of activated incorrect responses (i.e., a presumably higher conflict) would entail more pronounced conflict-related potentials. Indeed, two components of the N450 wave, parietal negativity and medial frontal negativity, were more negatively deflected when conflict was higher, than when it was lower, visibly responding to the level of conflict. Slow potential weakly responded to the sheer presence of conflict, but not to its level. These results can be plausibly explained by the conflict monitoring theory with a modified conflict evaluation formula, whereas they are at odds with several alternative theories of cognitive control.

Transient Distraction and Attentional Control during a Sustained Selective Attention Task.

Distracting stimuli in the environment can pull our attention away from our goal-directed tasks. fMRI studies have implicated regions in right frontal cortex as being particularly important for processing distractors [e.g., de Fockert, J. W., & Theeuwes, J. Role of frontal cortex in attentional capture by singleton distractors. Brain and Cognition, 80, 367-373, 2012; Demeter, E., Hernandez-Garcia, L., Sarter, M., & Lustig, C. Challenges to attention: A continuous arterial spin labeling (ASL) study of the effects of distraction on sustained attention. Neuroimage, 54, 1518-1529, 2011]. Less is known, however, about the timing and sequence of how right frontal or other brain regions respond selectively to distractors and how distractors impinge upon the cascade of processes related to detecting and processing behaviorally relevant target stimuli. Here we used EEG and ERPs to investigate the neural consequences of a perceptually salient but task-irrelevant distractor on the detection of rare target stimuli embedded in a rapid, serial visual presentation (RSVP) stream. We found that distractors that occur during the presentation of a target interfere behaviorally with detection of those targets, reflected by reduced detection rates, and that these missed targets show a reduced amplitude of the long-latency, detection-related P3 component. We also found that distractors elicited a right-lateralized frontal negativity beginning at 100 msec, whose amplitude negatively correlated across participants with their distraction-related behavioral impairment. Finally, we also quantified the instantaneous amplitude of the steady-state visual evoked potentials elicited by the RSVP stream and found that the occurrence of a distractor resulted in a transient amplitude decrement of the steady-state visual evoked potential, presumably reflecting the pull of attention away from the RSVP stream when distracting stimuli occur in the environment.

A functional classification of medial frontal negativity ERPs: Theta oscillations and single subject effects.

Theta oscillations in the EEG have been linked to several ERPs that are elicited during performance-monitoring tasks, including the error-related negativity (ERN), no-go N2, and the feedback-related negativity (FRN). We used a novel paradigm to isolate independent components (ICs) in single subjects' (n = 27) EEG accounting for a medial frontal negativity (MFN) to response cue stimuli that signal a potential change in future response demands. Medial frontal projecting ICs that were sensitive to these response cues also described the ERNs, no-go N2s, and, to a lesser extent, the FRNs, that were elicited in letter flanker, go/no-go, and time-estimation tasks, respectively. In addition, percentile bootstrap tests using trimmed means indicated that the medial frontal ICs show an increase in theta activity during the ERN, no-go N2, and FRN across tasks and within individuals. Our results provide an important validation of previous studies by showing that increases in medial frontal theta to cognitively challenging events in multiple paradigms is a reliable effect within individuals and can be elicited by basic stimulus cues that signal the potential need to adjust response control. Thus, medial frontal theta reflects a neural response common to all MFN paradigms and characterizes the general process of controlling attention without the need to induce error commission, inhibited responses, or to present negative feedback.

Direction matters: Event-related brain potentials reflect extra processing costs in switching from the dominant to the less dominant language

Abstract Language switching is common in bilingual processing, and it has been repeatedly shown to induce processing costs. However, only a handful of studies have examined such costs at the sentence level, with a limited few among them having incorporated factors extensively studied in monolingual sentence processing, such as semantic expectedness. Using the event related potentials (ERP) technique, this study aimed at exploring whether switching costs were modulated by (1) switching directions, when switching happens between languages of different dominance, and by (2) semantic expectedness, as indicated by cloze probability. Twenty-two Mandarin-Taiwanese early bilinguals, with Mandarin being their dominant and Taiwanese their non-dominant language, participated in the study. They were instructed to listen to the stimuli attentively and to perform a word memory recognition task in 20% of the trials. The results showed that switching induced an LPC effect, suggesting that switched elements were harder to be integrated. More importantly, switching from the dominant to the non-dominant language demanded extra effort than switching in the other direction, as reflected by the PMN (detection of an unexpected sound), the N400 (indication of lexical access difficulty) and the frontal negativity (inhibition of the pre-activated representations), revealing that the dominant language provides better prediction of the upcoming word. Also, cloze probability interacted with switching, but only at an early stage, suggesting that semantic expectedness did not enduringly modulate the switching cost. Our results generally supported predictions from the Bilingual Interactive Activation Plus model (BIA+ model, Dijkstra & van Heuven, 2002), showing that language use and sentence context can affect lexical processing in bilinguals.

Taking it easy when playing ultimatum game with a Down syndrome proposer: Effects on behavior and medial frontal negativity

ABSTRACTThe ultimatum game (UG) is an endowment sharing game in which a proposer suggests a division of an asset to a recipient, who must accept or reject it. Economic studies showed that despite recipients usually rejecting unfair offers, perception and reaction to unfairness are highly dependent on who is the proposer. Event-related potentials (ERPs) commonly detected in UG games are the medial frontal negativity (MFN), a component detected in recipients facing unfair offers, and the P300, a component related to attentional and memory processes. Given this, we aimed to investigate the behavioral and ERP responses of healthy people playing the UG game with Down syndrome (DS) and typical development (TD) proposers. Nineteen subjects participated in this study. The UG behavioral data were similar to previous studies. ERP analysis showed no MFN in participants facing unfair offers. A higher P300 amplitude was detected when participants faced fair offers from TD compared to DS fair offers. We also found a positive correlation between P300 amplitude for TD offers and self-esteem scale score. Together these findings indicate that insertion of an atypical player in the UG led to changes in participants’ perception and expectancy of the game.

A sheet of coffee: an event-related brain potential study of the processing of classifier-noun sequences in English and Mandarin

ABSTRACTComprehension of classifier-noun sequences was examined in separate studies in English and Mandarin by comparing event-related brain potential (ERP) responses to classifier-noun matches (a sheet of paper) and mismatches (a sheet of coffee) embedded in sentences. One goal was to determine which ERP components are sensitive to such mismatches, as a clue about the nature of the underlying combinatorial processes. Another goal was to examine effects of classifier constraint strength (a piece of … vs. a sheet of … ) on anticipation of a subsequent noun. Results were similar in the two languages, which is remarkable given substantial differences between them in classifier usage. In both languages, nouns evoked larger N400s in mismatching classifier-noun sequences, suggesting that combinatorial processing was primarily semantic, and general classifiers evoked a larger sustained frontal negativity than specific classifiers starting 200 milliseconds after classifier onset, reflecting effects of constraint strength on anticipation of the upcoming noun.

Medial frontal negativity reflects advantageous inequality aversion of proposers in the ultimatum game: An ERP study

Inequality aversion is a typical form of fairness preferences, which can explain the behaviors in many social exchange situations such as the ultimatum game (UG). There are two kinds of inequality aversion—disadvantageous inequality aversion of responders and advantageous inequality aversion of proposers in the ultimatum game. Although neuroscience research has reported neural correlates of disadvantageous inequality aversion, there are still debates about advantageous inequality aversion of proposers. In this paper, we developed a variant of ultimatum game in which participants played the UG as proposers. On each trial, first, the offer was randomly presented, then, participants as proposers decided whether to choose this offer; next, responders decided whether to accept or not. Offers that responders got 1–20% of the pie are defined as advantageous unfair offers of proposers, whereas offers that responders got 31–50% are defined as fair offers. Event-related brain potentials recorded from the participants showed that more negative-going medial frontal negativity (MFN) was elicited by advantageous unfair offers compared to fair offers in the early time window (250–350ms), which suggested that proposers were averse to advantageous inequality.

Reaction Time in a Visual 4-Choice Reaction Time Task: ERP Effects of Motor Preparation and Hemispheric Involvement.

Reaction time (RT), the most common measure of CNS efficiency, shows intra- and inter-individual variability. This may be accounted for by hemispheric specialization, individual neuroanatomy, and transient functional fluctuations between trials. To explore RT on these three levels, ERPs were measured in a visual 4-choice RT task with lateralized stimuli (left lateral, left middle, right middle, and right lateral) in 28 healthy right-handed subjects. We analyzed behavioral data, ERP microstates (MS), N1 and P3 components, and trial-by-trial variance. Across subjects, the N1 component was contralateral to the stimulation side. N1-MSs were stronger over the left hemisphere, and middle stimulation evoked stronger activation than lateral stimulation in both hemispheres. The P3 was larger for the right visual field stimulation. RTs were shorter for the right visual hemifield stimulation/right hand responses. Within subjects, covariance analysis of single trial ERPs with RTs showed consistent lateralized predictors of RT over the motor cortex (MC) in the 112-248ms interval. Decreased RTs were related to negativity over the MC contralateral to the stimulation side, an effect that could be interpreted as the lateralized readiness potential (LRP), and which was strongest for right side stimulation. The covariance analysis linking individual mean RTs and individual mean ERPs showed a frontal negativity and an occipital positivity correlating with decreased RTs in the 212-232ms interval. We concluded that a particular RT is a composite measure that depends on the appropriateness of the motor preparation to a particular response and on stimulus lateralization that selectively involves a particular hemisphere.

Neurophysiological modulation of rapid emotional face processing is associated with impulsivity traits.

BackgroundSensori-perceptual processing of emotional stimuli under attentive conditions effectively prevents response disinhibition. This is observed saliently in low-impulsive people, because of their high sensitivity to warning signals, such as emotional faces. Results from human neurophysiological studies have been used to develop a dual detector model for early sensori-perceptual processing. A transient detector mechanism is related to automatic neurophysiological arousal in response to warning signals, which is reflected by early frontal event-related potential effects. The memory-based detector mechanism is associated with subsequent mismatch negativity (MMN), which reflects a short-term memory trace of signals. Based on previous findings, we predicted that impulsivity affects functional associations among the dual detector mechanisms, and modulates early frontal and/or MMN activities. In the present study, we recorded electroencephalograms for twenty-one healthy adults using a visual oddball paradigm with neutral faces as frequent stimuli, and angry and happy faces as infrequent stimuli. We measured the impulsivity traits by a self-report scale (the Barratt Impulsiveness Scale, 11th version).ResultsMain findings were that only happy faces increased early frontal negativity and subsequent occipital visual MMN (vMMN) for emotional change, and these neurophysiological effects positively correlated with each other in a temporally causal manner. However, an impulsivity sub-trait positively correlated selectively with vMMN for the happy faces.ConclusionThese findings demonstrate that higher impulsivity is associated with attenuated vMMN for emotional change detection in healthy populations, potentially because of weakened fronto-occipital functional connection that is responsible for the dual detector mechanism.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-015-0223-x) contains supplementary material, which is available to authorized users.

Human recognition memory and conflict control: An event-related potential study

The relationship between recognition memory and cognitive control is an important research topic. The current study investigated how conflict control influences an individual’s emotional memory. During the encoding phase, participants were required to judge the affective valence of a Chinese Chengyu word (either positive or negative) in a modified Simon paradigm and to remember the word. Half of the words were presented in the congruent condition and the other half were displayed in the incongruent condition. During the retrieval phase, participants were instructed to make an ‘old/new judgment’ and decide whether the word had been presented previously. Electrophysiological responses were recorded using the event-related potential (ERP) technique. The behavioral results of retrieval processes showed that participants remembered more positive than negative words when they were encoded in the congruent condition. The electrophysiological results revealed that the retrieval of words encoded in the incongruent condition elicited less negative frontal negativity (FN) and early posterior negativity (EPN) amplitudes than those encoded in the congruent condition. The retrieval of words encoded in the incongruent condition induced greater late positive complex (LPC) amplitudes, relative to those encoded in the congruent condition on the left hemisphere. It was also observed that the recognition of positive words induced faster LPC responses than negative words when they were encoded in the incongruent condition. The present electrophysiological study illustrates that emotional memory processes may be affected by conflict control.

The Virtual Tray of Objects Task as a novel method to electrophysiologically measure visuo-spatial recognition memory

We explored a novel method to electrophysiologically measure visuo-spatial recognition memory using a modified version of the Virtual Tray of Objects Task (VTOT). Event-related potentials (ERP) were recorded from 18 healthy volunteers during performance in the VTOT. Participants were required to detect random repetitions of three-dimensional visual stimuli (OLD) and to refrain from responding to non-repeated stimuli (NEW). Differences in ERP between the NEW and OLD conditions were tested for statistical significance using assumption-free non-parametric analyses. Further, a correlation between ERP and behavioral measures was sought. Significant OLD-NEW effects were found for four ERP components showing distinct spatio-temporal characteristics: a posterior positive component appearing at 100ms (P100), a left-lateralized negative component peaking at ≈250ms (N250), a frontal negative component at ≈300–450ms (FN400), and a right late frontal negativity (rLFN) at ≈500–720ms. Moreover, individual differences in the OLD-NEW effect computed for the rLFN positively correlated with repeated stimulus recognition efficiency. However, there were no late left parietal P600 old/new effects. These findings suggest that the P100 component might reflect early visual perception processes taking place during performance in the task, whereas the N250 and FN400 components could be linked to stimulus-dependent access to visual memory representations and familiarity-related processes, respectively. In contrast, we propose that the rLFN component could be associated with higher-level cognitive functions, such as attention and monitoring processes. Altogether, our results suggest that the ERP version of the VTOT could play a role in the electrophysiological assessment of visuo-spatial memory and related sub-processes.

Old-new ERP effects and remote memories: the late parietal effect is absent as recollection fails whereas the early mid-frontal effect persists as familiarity is retained

Understanding the electrophysiological correlates of recognition memory processes has been a focus of research in recent years. This study investigated the effects of retention interval on recognition memory by comparing memory for objects encoded four weeks (remote) or 5 min (recent) before testing. In Experiment 1, event related potentials (ERPs) were acquired while participants performed a yes-no recognition memory task involving remote, recent and novel objects. Relative to correctly rejected new items, remote and recent hits showed an attenuated frontal negativity from 300–500 ms post-stimulus. This effect, also known as the FN400, has been previously associated with familiarity memory. Recent and remote recognition ERPs did not differ from each other at this time-window. By contrast, recent but not remote recognition showed increased parietal positivity from around 500 ms post-stimulus. This late parietal effect (LPE), which is considered a correlate of recollection-related processes, also discriminated between recent and remote memories. A second, behavioral experiment confirmed that remote memories unlike recent memories were based almost exclusively on familiarity. These findings support the idea that the FN400 and LPE are indices of familiarity and recollection memory, respectively and show that remote and recent memories are functionally and anatomically distinct.

Rejection in Bargaining Situations: An Event-Related Potential Study in Adolescents and Adults.

The neural correlates of rejection in bargaining situations when proposing a fair or unfair offer are not yet well understood. We measured neural responses to rejection and acceptance of monetary offers with event-related potentials (ERPs) in mid-adolescents (14–17 years) and early adults (19–24 years). Participants played multiple rounds of the Ultimatum Game as proposers, dividing coins between themselves and a second player (responder) by making a choice between an unfair distribution (7 coins for proposer and 3 for responder; 7/3) and one of two alternatives: a fair distribution (5/5) or a hyperfair distribution (3/7). Participants mostly made fair offers (5/5) when the alternative was unfair (7/3), but made mostly unfair offers (7/3) when the alternative was hyperfair (3/7). When participants’ fair offers (5/5; alternative was 7/3) were rejected this was associated with a larger Medial Frontal Negativity (MFN) compared to acceptance of fair offers and rejection of unfair offers (7/3; alternative was 3/7). Also, the MFN was smaller after acceptance of unfair offers (7/3) compared to rejection. These neural responses did not differ between adults and mid-adolescents, suggesting that the MFN reacts as a neural alarm system to social prediction errors which is already prevalent during adolescence.