Late Positive Event-related Potentials Research Articles

Dyadic cooperation with human and artificial agents: Event-related potentials trace dynamic role taking during an interactive game.

Humans are highly co-operative and thus cognitively, affectively, and motivationally tuned to pursue shared goals. Yet, cooperative tasks typically require people to constantly take and switch individual roles. Task relevance is dictated by these roles and thereby dynamically changing. Here, we designed a dyadic game to test whether the family of P3 components can trace this dynamic allocation of task relevance. We demonstrate that late positive event-related potential (ERP) modulations not only reflect predictable asymmetries between receiving and sending information but also differentiate whether the receiver's role is related to correct decision making or action monitoring. Furthermore, similar results were observed when playing the game with a computer, suggesting that experimental games may motivate humans to similarly cooperate with an artificial agent. Overall, late positive ERP waves provide a real-time measure of how role taking dynamically shapes the meaning and relevance of stimuli within collaborative contexts. Our results, therefore, shed light on how the processes of mutual coordination unfold during dyadic cooperation.

How do medical students understand disease behaviors? Evidence from event-related potentials

To investigate how medical students process Western medicine (WM) terms vs . traditional Chinese medicine (TCM) terms and how this is impacted by analogical priming from the perspective of cognitive neuroscience. The experiments were designed as a 2 (TCM terms vs . WM terms) × 2 (correct terms vs . incorrect terms) × 2 (analogical priming task vs . non-priming task) scheme. A total of 26 medical students completed a non-priming judgment task and an analogical priming judgment task on medical terms. During the tasks, the participants were asked to make correct/incorrect judgments on WM terms and TCM terms, and their behavioral data and event-related potentials (ERPs) were recorded. Behaviorally, the response speed and accuracy of WM terms were higher than those of TCM terms (both P < .001), indicating a prominent concreteness effect. Analogical priming shortened the response time to medical terms ( P < .001), and the response time to TCM terms was shortened more significantly ( P = .001). For ERPs, WM terms induced a larger P200 (an early positive ERP component), a smaller N400 (a negative ERP component), and a higher late positive ERP component, indicating superiority of attention adjustment, smaller-scale semantic activation, and a higher cost of late semantic analysis and integration. However, the analogical priming eliminated the difference between WM and TCM terms in P200 and N400 while maintaining it in the LPC. This suggests that WM terms are sensitive to analogical attention adjustment, and TCM terms are susceptible to analogical semantic integration. Our findings suggest that WM and TCM disease behavior terms may initially differ in concreteness or the use of a verbal-linguistic system. Analogy is more conducive to understanding TCM terms. This research provides important neuroscientific evidence of the difference in thinking between TCM and WM.

Individual Differences in Working Memory Capacity Modulate Electrophysiological Correlates of Semantic Negative Priming From Single Words.

In the present study, event-related potentials (ERPs) were registered during a semantic negative priming (NP) task in participants with higher and lower working memory capacity (WMC). On each trial participants had to actively ignore a briefly presented single prime word, which was followed either immediately or after a delay by a mask. Thereafter, either a semantically related or an unrelated target word was presented, to which participants made a semantic categorization judgment. The ignored prime produced a behavioral semantic NP in delayed (but not in immediate) masking trials, and only for participants with a higher-WMC. Both masking type and WMC also modulated ERP priming effects. When the ignored prime was immediately followed by a mask (which impeded its conscious identification) a reliable N400 modulation was found irrespective of participants’ WMC. However, when the mask onset following the prime was delayed (thus allowing its conscious identification), an attenuation of a late positive ERP (LPC) was observed in related compared to unrelated trials, but only in the higher-WMC group showing reliable behavioral NP. The present findings demonstrate for the first time that individual differences in WMC modulate both behavioral measures and electrophysiological correlates of semantic NP.

Decoding Neural Representations of Affective Scenes in Retinotopic Visual Cortex.

The perception of opportunities and threats in complex visual scenes represents one of the main functions of the human visual system. The underlying neurophysiology is often studied by having observers view pictures varying in affective content. It has been shown that viewing emotionally engaging, compared with neutral, pictures (1) heightens blood flow in limbic, frontoparietal, and anterior visual structures and (2) enhances the late positive event-related potential (LPP). The role of retinotopic visual cortex in this process has, however, been contentious, with competing theories predicting the presence versus absence of emotion-specific signals in retinotopic visual areas. Recording simultaneous electroencephalography-functional magnetic resonance imaging while observers viewed pleasant, unpleasant, and neutral affective pictures, and applying multivariate pattern analysis, we found that (1) unpleasant versus neutral and pleasant versus neutral decoding accuracy were well above chance level in retinotopic visual areas, (2) decoding accuracy in ventral visual cortex (VVC), but not in early or dorsal visual cortex, was correlated with LPP, and (3) effective connectivity from amygdala to VVC predicted unpleasant versus neutral decoding accuracy, whereas effective connectivity from ventral frontal cortex to VVC predicted pleasant versus neutral decoding accuracy. These results suggest that affective scenes evoke valence-specific neural representations in retinotopic visual cortex and that these representations are influenced by reentry signals from anterior brain regions.

Functional Linking Between Negative and Positive ERPs for Syntactic Processing in Japanese: Mutual Enhancement, Syntactic Prediction, and Working Memory Constraints.

This study attempts to detect the differences in event-related potentials (ERPs) associated with two syntactic processes: the syntactic integration of discontinuous dependency and the detection of a violation of the syntactic island constraint. We recorded the electroencephalogram elicited by complex sentences in Japanese that included a dependency between a quantifier and its head noun, in which we changed the word order of the two words to manipulate the presence and absence of a syntactic integration and a syntactic island violation while keeping the lexical items and construction unchanged. We found significant negative and positive deflections for the syntactic integration only when a quantifier preceded its head noun. We also observed significant negative and positive deflections for the syntactic island violation, for which the negativity was more salient when a quantifier preceded its head noun. This study is the first to report a late positive ERP for a violation of the syntactic island constraints in Japanese, and the results showed that the ERP elicited by syntactic integration and that by syntactic island violation were different in terms of their latency, topography, and duration. More importantly, the ERPs elicited by the two syntactic processes were biphasic, and the amplitudes of the negative ERP and of the positive ERP were positively correlated. This positive correlation could be a characteristic of syntactic processing because it contrasted with the negative correlation reported for the ERP elicited by semantic anomalies in English. Furthermore, the amplitude of the ERP for syntactic integration was negatively correlated with the individual capacity of working memory (WM). That is, a reader with greater WM capacity showed smaller negativity and positivity for the syntactic integration, whereas the amplitude for the syntactic island violation showed no significant correlation with the individual capacity of WM. Our results suggested that linguistic ERPs functionally interacted with each other and that the ERP involving the retention and the retrieval of a distant word could be constrained by the individual differences in WM capacity. We discuss the possible reasons for the contrast between English and Japanese on the basis of the cross-linguistic differences in the two languages.

Dissociating predictability, plausibility and possibility of sentence continuations in reading: evidence from late-positivity ERPs.

Late positive event-related potential (ERP) components occurring after the N400, traditionally linked to reanalysis due to syntactic incongruence, are increasingly considered to also reflect reanalysis and repair due to semantic difficulty. Semantic problems can have different origins, such as a mismatch of specific predictions based on the context, low plausibility, or even semantic impossibility of a word in the given context. DeLong, Quante & Kutas (2014) provided the first direct evidence for topographically different late positivities for prediction mismatch (left frontal late positivity for plausible but unexpected words) and plausibility violation (posterior-parietal late positivity for implausible, incongruent words). The aim of the current study is twofold: (1) to replicate this dissociation of ERP effects for plausibility violations and prediction mismatch in a different language, and (2) to test an additional contrast within implausible words, comparing impossible and possible sentence continuations. Our results replicate DeLong, Quante & Kutas (2014) with different materials in a different language, showing graded effects for predictability and plausibility at the level of the N400, a dissociation of plausible and implausible, anomalous continuations in posterior late positivities and an effect of prediction mismatch on late positivities at left-frontal sites. In addition, we found some evidence for a dissociation, at these left-frontal sites, between implausible words that were fully incompatible with the preceding discourse and those for which an interpretation is possible.

Electrophysiological correlates of word recognition memory process in patients with ischemic left ventricular dysfunction.

The relationship between left ventricular ejection fraction (LVEF) and cognitive performance in patients with coronary artery disease without overt heart failure is still under debate. In this study we combine behavioral measures and event-related potentials (ERPs) to verify whether electrophysiological correlates of recognition memory (old/new effect) are modulated differently as a function of LVEF. Twenty-three male patients (12 without [LVEF>55%] and 11 with [LVEF<40%] left ventricular dysfunction), and a Mini Mental State Examination score >25 were enrolled. ERPs were recorded while participants performed an old/new visual word recognition task. A late positive ERP component between 350 and 550ms was differentially modulated in the two groups: a clear old/new effect (enhanced mean amplitude for old respect to new items) was observed in patients without LVEF dysfunction; whereas patients with overt LVEF dysfunction did not show such effect. In contrast, no significant differences emerged for behavioral performance and neuropsychological evaluations. These data suggest that ERPs may reveal functional brain abnormalities that are not observed at behavioral level. Detecting sub-clinical measures of cognitive decline may contribute to set appropriate treatments and to monitor asymptomatic or mildly symptomatic patients with LVEF dysfunction.

Exposure to social-evaluative video clips: Neural, facial-muscular, and experiential responses and the role of social anxiety

Engaging in social interaction often implies being evaluated. Receiving positive evaluations from others may elicit affiliative emotions whereas negative evaluations are likely to trigger withdrawal and defensive social behavior. Evolution has equipped humans with efficient systems to detect, appraise, and regulate responses to such evaluative communications and to express complementary responses. The current study investigates neural, facial-muscular, and experiential responses to short videos delivering neutral, positive, and negative audiovisual messages as well as their relation to individual differences in social anxiety. Fifty-eight participants (32 female) watched 90 videos with male and female actors displaying positive, negative, and neutral statements. Experientially, ratings of valence and arousal showed the expected category differences. Neurally, larger centro-parietal late positive event related potentials were found for emotional (positive and negative) videos compared to neutral videos. Facial electromyography revealed reduced corrugator muscle and increased zygomaticus major muscle activity for positive videos compared to neutral and negative videos. Cognitive components of social anxiety were related to a more unpleasant experience of negative videos and a less pleasant experience of positive videos. Thus, a set of neural, facial-muscular, and experiential responses contribute to social interaction in the context of relatively naturalistic social-evaluative stimuli.

32. Event-related potential correlates of word recognition memory in patients with coronary artery disease

The relationship between left ventricular ejection fraction (LVEF) and cognitive performance in patients with coronary artery disease (CAD) without overt heart failure is still under debate. In the present study we combine behavioural measures and event-related potentials (ERPs) to verify whether electrophysiological correlates of recognition memory (Old/New effect) is modulated differently as a function of LVEF. Twenty-five male patients with CAD (13 without [LVEF > 55%] and 12 with [LVEF < 40%] left ventricular dysfunction), and a Mini Mental State Examination score > 25 were enrolled. ERPs were recorded while participants performed a visual word recognition task consisting of a test phase in which they were asked to judge whether visual stimuli were previously presented in a learning phase (‘old’) or not (‘new’). ERPs responses from the test phase were analyzed. A late positive ERP component between 300 and 500 ms was differentially modulated in the two groups: a clear old/new effect (enhanced mean amplitude for old respect to new items) was observed in patients without LVEF dysfunction; whereas patients with overt LVEF dysfunction did not show such old/new effect. These data suggest that ERPs may reveal possible functional brain abnormalities that might be not observed at behavioural levels.

Vocal emotions influence verbal memory: Neural correlates and interindividual differences

Past research has identified an event-related potential (ERP) marker for vocal emotional encoding and has highlighted vocal-processing differences between male and female listeners. We further investigated this ERP vocal-encoding effect in order to determine whether it predicts voice-related changes in listeners' memory for verbal interaction content. Additionally, we explored whether sex differences in vocal processing would affect such changes. To these ends, we presented participants with a series of neutral words spoken with a neutral or a sad voice. The participants subsequently encountered these words, together with new words, in a visual word recognition test. In addition to making old/new decisions, the participants rated the emotional valence of each test word. During the encoding of spoken words, sad voices elicited a greater P200 in the ERP than did neutral voices. While the P200 effect was unrelated to a subsequent recognition advantage for test words previously heard with a neutral as compared to a sad voice, the P200 did significantly predict differences between these words in a concurrent late positive ERP component. Additionally, the P200 effect predicted voice-related changes in word valence. As compared to words studied with a neutral voice, words studied with a sad voice were rated more negatively, and this rating difference was larger, the larger the P200 encoding effect was. While some of these results were comparable in male and female participants, the latter group showed a stronger P200 encoding effect and qualitatively different ERP responses during word retrieval. Estrogen measurements suggested the possibility that these sex differences have a genetic basis.

Impaired engagement of the ventral attentional pathway in ADHD

In the cognitive theories of Attention Deficit Hyperactivity Disorder (ADHD) impaired behavioral adjustment has been linked to a deficit in learning to detect regularities or irregularities in the environment. In the neural level, the P3 component of event-related potential (ERP) is modulated by stimulus probability and has been suggested to index activation of the ventral attention network, which constitutes the reorienting system of the human brain. To explore the cortical basis of late positive ERP components and the engagement of the ventral attentional pathway in ADHD, we used ERP recordings complemented by spatiotemporally sensitive magnetoencephalography (MEG) measurements. We followed the activation evoked by frequent Go and infrequent NoGo stimuli in 10 ADHD adults and 13 control subjects. In the ERP recordings, a prominent positive deflection was detected after the infrequent visual stimuli (late positive component, LPC) in both subject groups. In ADHD adults the difference between the responses evoked by infrequent NoGo and frequent Go stimuli was markedly reduced compared to the control group during the LPC. The MEG recordings revealed that the activation detected during the LPC was localized bilaterally in the posterior temporal cortex. Activation of the left and right temporal regions was enhanced after infrequent NoGo stimuli in both subject groups. In ADHD adults, however, the effect of stimulus frequency was less pronounced. We suggest that the activation in the superior temporal cortices during the LPC reflects the action of ventral attention network. The engagement of this stimulus-driven reorienting system is defective in ADHD.

Investigating the neural correlates of metamemory using functional magnetic resonance imaging (fMRI) and intracranial electroencephalography (IEEG)

Event Abstract Back to Event Investigating the neural correlates of metamemory using functional magnetic resonance imaging (fMRI) and intracranial electroencephalography (IEEG) Anne T. Do Lam1*, Nikolai Axmacher1, Christian E. Elger1 and Juergen Fell1 1 Epileptology University Bonn, Germany Memory performance in everyday life is often far from perfect. Thus, people usually monitor and control the learning progress by metamemory evaluations, such as judgments of learning (JOLs). We first investigated the neural correlates of JOLs using fMRI in 17 healthy subjects with a face – name paired associates design. In general, we found that actual memory success was associated with increased brain activation of bilateral hippocampi but dissociated from predicted memory which was correlated with larger brain activation of a prefrontal network. Since we found that the hippocampus was recruited during the JOL phase, we conducted an iEEG study in 11 presurgical epilepsy patients with hippocampal and rhinal depth electrodes. Patients were presented with unfamiliar faces and had to provide JOLs. In the subsequent retrieval phase, faces were shown again intermixed with 50 % new faces for a recognition memory test. Analyses of event-related potentials (ERP) of remembered versus forgotten trials yielded increases of the rhinal N400 component, as well as of late positive hippocampal ERP components. The memory predictions revealed only significant differences of hippocampal ERPs. However, accurate memory predictions were correlated with effects in the rhinal cortex in an early and late time phase, and with a late ERP effect in the hippocampus. Our data demonstrate that memory predictions per se rely on hippocampal activation, whereas accurate predictions might require an interaction of neocortical areas mediating monitoring/ control of incoming information, and the hippocampus. We suggest that this interaction is reflected by early and late rhinal ERP effects. The latter effects were not observed during memory encoding indicating that JOLs do not reduce to encoding processes. Keywords: cognitive control, ERP Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Performance Monitoring and Cognitive Control Citation: Do Lam AT, Axmacher N, Elger CE and Fell J (2011). Investigating the neural correlates of metamemory using functional magnetic resonance imaging (fMRI) and intracranial electroencephalography (IEEG). Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00245 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Anne T Do Lam, Epileptology University Bonn, Bonn, Germany, anne.dolam@ukb.uni-bonn.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Anne T Do Lam Nikolai Axmacher Christian E Elger Juergen Fell Google Anne T Do Lam Nikolai Axmacher Christian E Elger Juergen Fell Google Scholar Anne T Do Lam Nikolai Axmacher Christian E Elger Juergen Fell PubMed Anne T Do Lam Nikolai Axmacher Christian E Elger Juergen Fell Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Keeping an eye on the truth: Pupil size, recognition memory and malingering

Background: Estimates of the incidence of malingering in patient populations vary from 1 to 12%, rising to ∼25% in patients seeking financial compensation. Malingering is particularly difficult to detect when patients feign poor performance on neuropsychological tests (see Hutchinson, 2001). One strategy to detect malingering has been to identify psychophysiological markers associated with deception. Tardif, Barry, Fox and Johnstone (2000) used electroencephalogram (EEG) recording to measure event related potentials (ERPs) during a standard recognition memory test. Previous research has documented an ERP “old/new effect” – late positive parietal ERPs are larger when participants view old, learned words compared to new words during recognition. Tardif et al. reasoned that if this effect is not under conscious control, then it should be equally detectable in people feigning amnesia as in participants performing to their best ability. As predicted, they found no difference in the magnitude and topography of the old/new ERP effect between participants who were asked to feign amnesia whilst performing the test and those asked to perform to their best ability. Whilst this approach shows some promise, EEG is comparatively time consuming and expensive. Previous research has shown that during recognition memory tests, participants' pupils dilate more when they view old items compared to new items (Otero, Weeks, and Hutton, 2006; Vo et al., 2008). This pupil “old/new effect” may present a simpler means by which to establish whether participants are feigning amnesia. Method: We used video-based oculography to compare changes in pupil size during a recognition memory test when participants were given standard recognition memory instructions, instructions to feign amnesia and instructions to report all items as new. Due to constant fluctuation in pupil size over time, and variation between individuals, a pupil dilation ratio (PDR) was calculated that represented the maximum pupil size during the trial as a proportion of the maximum during baseline. Results: Participants' pupils dilated more to old items compared to new items under all three instruction conditions (F(1.25) = 47.02, MSE < 0.001, p < .001, ηp2 = .65). There were no significant differences between baseline pupil size (F(1.63,40.76) = 1.90, p = .17, ns). Conclusions: The finding that under standard recognition memory instructions, participants' relative increase in pupil size is greater when they view old items compared to new items replicates previous research documenting the pupil old/new effect. That the effect persists, even when participants give erroneous responses during recognition, suggests that the “pupil old/new effect” is not under conscious control and may therefore have potential use in clinical settings as a simple means with which to detect whether patients are feigning amnesia.

Activity of hippocampal, amygdala, and neocortex during the Rey auditory verbal learning test: An event-related potential study in epileptic patients

Previous evidence in epileptic subjects has shown that theta (about 4-7Hz) and gamma rhythms (about 40-45Hz) of hippocampus, amygdala, and neocortex were temporally synchronized during the listening of repeated words successfully remembered (Babiloni et al., 2009). Here we re-analyzed those electroencephalographic (EEG) data to test whether a parallel increase in amplitude of late positive event-related potentials takes place. Intracerebral electroencephalographic (EEG) activity had been recorded in five subjects with drug-resistant temporal lobe epilepsy, undergoing pre-surgical evaluation. During the recording of the intracerebral EEG activity, the subjects performed a computerized version of the Rey auditory verbal learning test (RAVLT). They heard the same list of 15 common words for five times. Each time, immediately after the listening of the list, the subjects were required to repeat as many words as they could recall. We found that late positive event-related potentials (ERPs) peaking at about 350ms post-stimulus in amygdala, hippocampus, and occipital-temporal cortex had a higher amplitude during the listening of the repeated words that were subsequently recalled than for those that were not recalled. Late positive ERPs reflect a functional mechanism implemented in a human brain network spanning amygdala, hippocampus, and occipital-temporal cortex which is at the basis of the memorization processes of verbal materials. This ERP component is a promising neuromarker of successful memorization of repeated words in humans.

Objective selection of EEG late potentials through residual dependence estimation of independent components

This paper presents a novel method to objectively select electroencephalographic (EEG) cortical sources estimated by independent component analysis (ICA) in event-related potential (ERP) studies. A proximity measure based on mutual information is employed to estimate residual dependences of the components that are then hierarchically clustered based on these residual dependences. Next, the properties of each group of components are evaluated at each level of the hierarchical tree by two indices that aim to assess both cluster tightness and physiological reliability through a template matching process. These two indices are combined in three different approaches to bring to light the hierarchical structure of the cluster organizations. Our method is tested on a set of experiments with the purpose of enhancing late positive ERPs elicited by emotional picture stimuli. Results suggest that the best way to look for physiologically plausible late positive potential (LPP) sources is to explore in depth the tightness of those clusters that, taken together, best resemble the template. According to our results, after brain sources clustering, LPPs are always identified more accurately than from ensemble-averaged raw data. Since the late components of an ERP involve the same associative areas, regardless of the modality of stimulation or specific tasks administered, the proposed method can be simply adapted to other ERP studies, and extended from psychophysiological studies to pathological or sport training evaluation support.

Food cue-elicited brain potentials in obese and healthy-weight individuals

The main objective of this study was to investigate, by means of event-related potentials (ERPs), whether obese individuals process food-related information differently as compared to normal-weight individuals. Because amplitudes of late positive ERP components (P3, LPP) reflect motivational tendencies, obese participants were expected to display enlarged P3 and LPP amplitudes towards food pictures. Obese and normal-weight adults were exposed to pictures of food and control items, while EEG was recorded. Subjective levels of food craving and hunger were also assessed. While there were no differences in ERP amplitudes between obese and normal-weight individuals, significantly larger P3 and LPP amplitudes were elicited by pictures of food items as compared to control pictures. Positive correlations were found between P3 and LPP amplitudes and self-reported increases of hunger. It was concluded that food-related information is processed differently in the brain as compared to non-food-related information, in a manner that reflects the natural motivational value of food. In the present study, there was no indication of an electrophysiological or subjective hyper-reactivity to food cues in obese adults.

Neural activities of tactile cross-modal working memory in humans: an event-related potential study

In the present study, we examined the neural mechanisms underlying cross-modal working memory by analyzing scalp-recorded event-related potentials (ERPs) from normal human subjects performing tactile–tactile unimodal or tactile–auditory cross-modal delay tasks that consisted of stimulus-1 (S-1, tactile), interval (delay), and stimulus-2 (S-2, tactile or auditory). We hypothesized that there would be sequentially discrete task-correlated changes in ERPs representing neural processes of tactile working memory, and in addition, significant differences would be observed in ERPs between the unimodal task and the cross-modal task. In comparison to the ERP components in the unimodal task, two late positive ERP components (LPC-1 and LPC-2) evoked by the tactile S-1 in the delay of the cross-modal task were enhanced by expectation of the associated auditory S-2 presented at the end of the delay. Such enhancement might represent neural activities involved in cross-modal association between the tactile stimulus and the auditory stimulus. Later in the delay, a late negative component (LNC) was observed. The amplitude of LNC depended on information retained during the delay, and when the same information was retained, this amplitude was not influenced by modality or location of S-2 (auditory S-2 through headphones, or tactile S-2 on the left index finger). LNC might represent the neural activity involved in working memory. The above results suggest that the sequential ERP changes in the present study represent temporally distinguishable neural processes, such as the cross-modal association and cross-modal working memory.

Neuroaffective Processing in Criminal Psychopaths: Brain Event-Related Potentials Reveal Task-Specific Anomalies

This study aimed to confirm neuroaffective processing deficits in psychopaths by measuring late brain event-related potential (ERP) components and behavior in groups of psychopathic and nonpsychopathic inmates of a Singaporean prison while they performed two tasks. In a Categorization task, affective stimuli were task-relevant and required focused attention, while in a Vigilance task, affective pictures were presented in the background while participants discriminated vertical from oblique lines. Psychopaths showed differences in late positive ERPs that were sensitive to affective stimulus properties (valence and arousal) in the Categorization, but not in the Vigilance task, suggesting that only under conditions of focused attention did psychopaths show a neuroaffective processing deficit. In the Categorization task, psychopaths also showed a significantly larger prefrontal negative ERP (N350) whose amplitude correlated positively with the behavioral facet of psychopathy. In the Vigilance task, psychopaths both missed more targets and showed significantly smaller target-evoked parietal ERPs when viewing arousing pictures, suggesting their attentional focus was disrupted by the affective background.

Olfactory Event-Related Potentials Reflect Individual Differences in Odor Valence Perception

Investigating the neural substrates of perceived quality in olfaction using different odorants is intrinsically difficult. By utilizing individual differences in perceived quality of the odor of androstenone, we obtained a continuum of individual differences in rated valence of the same stimulus allowing investigations of its manifestation in the olfactory event-related potentials (ERPs). In an initial group consisting of 43 individuals that were screened for their verbal descriptors and sensitivity for the odor of androstenone, 22 normosmic volunteers were chosen forming 2 distinct groups with regard to verbal labels ("body odor" and "nonbody odor") for androstenone while maintaining chemical structure, concentration, and intensity constant. In the main experiment, these participants rated both intensity and pleasantness of androstenone during the recording of olfactory ERPs. There was a significant difference in rated valence between the groups but not in intensity. Participants in the body odor label group had larger amplitudes of the late positive ERP component than those in the nonbody odor label group. A negative correlation between valence and amplitudes of the late positive component for androstenone indicated that these differences were mediated by the difference in odor valence between the 2 groups. This was further supported by a comparison of ERP peaks in response to stimulation with androstenone and the invariably unpleasant hydrogen sulfide that had been used as a control. Altogether, the results suggest that the late positive component reflects the processing of odor valence. Future olfactory studies with the aim of assessing the dimension of pleasantness would benefit from the use of these interindividual differences in the perception of a specific odor.

Neural responses elicited to face motion and vocalization pairings

During social interactions our brains continuously integrate incoming auditory and visual input from the movements and vocalizations of others. Yet, the dynamics of the neural events elicited to these multisensory stimuli remain largely uncharacterized. Here we recorded audiovisual scalp event-related potentials (ERPs) to dynamic human faces with associated human vocalizations. Audiovisual controls were a dynamic monkey face with a species-appropriate vocalization, and a house with opening front door with a creaking door sound. Subjects decided if audiovisual stimulus trials were congruent (e.g. human face–human sound) or incongruent (e.g. house image–monkey sound). An early auditory ERP component, N140, was largest to human and monkey vocalizations. This effect was strongest in the presence of the dynamic human face, suggesting that species-specific visual information can modulate auditory ERP characteristics. A motion-induced visual N170 did not change amplitude or latency across visual motion category in the presence of sound. A species-specific incongruity response consisting of a late positive ERP at around 400ms, P400, was selectively larger only when human faces were mismatched with a non-human sound. We also recorded visual ERPs at trial onset, and found that the category-specific N170 did not alter its behavior as a function of stimulus category—somewhat unexpected as two face types were contrasted with a house image. In conclusion, we present evidence for species-specificity in vocalization selectivity in early ERPs, and in a multisensory incongruity response whose amplitude is modulated only when the human face motion is paired with an incongruous auditory stimulus.