Separating the visual sentence N400 effect from the P400 sequential expectancy effect: Cognitive and neuroanatomical implications

Neurophysiological insights into sequential decision-making: exploring the secretary problem through ERPs and TBR dynamics

Decision-making under uncertainty, a cornerstone of human cognition, is encapsulated by the "secretary problem" in optimal stopping theory. Our study examines this decision-making challenge, where participants are required to sequentially evaluate and make irreversible choices under conditions that simulate cognitive overload. We probed neurophysiological responses by engaging 27 students in a secretary problem simulation while undergoing EEG monitoring, focusing on Event-Related Potentials (ERPs) P200 and P400, and Theta to Beta Ratio (TBR) dynamics.Results revealed a nuanced pattern: the P200 component's amplitude declined from the initial to the middle offers, suggesting a diminishing attention span as participants grew accustomed to the task. This attenuation reversed at the final offer, indicating a heightened cognitive processing as the task concluded. In contrast, the P400 component's amplitude peaked at the middle offer, hinting at increased cognitive evaluation, and tapered off at the final decision. Additionally, TBR dynamics illustrated a fluctuation in attentional control and emotional regulation throughout the decision-making sequence, enhancing our understanding of the cognitive strategies employed.The research elucidates the dynamic interplay of cognitive processes in high-stakes environments, with neurophysiological markers fluctuating significantly as participants navigated sequential choices. By correlating these fluctuations with decision-making behavior, we provide insights into the evolving strategies from heightened alertness to strategic evaluation. Our findings offer insights that could inform the use of neurophysiological data in the development of decision-making frameworks, potentially contributing to the practical application of cognitive research in real-life contexts.

Age-related differences in food-specific inhibitory control: Electrophysiological and behavioral evidence in healthy aging

The number of older adults in the United States is estimated to nearly double from 52 million to 95 million by 2060. Approximately 80-85% of older adults are diagnosed with a chronic health condition. Many of these chronic health conditions are influenced by diet and physical activity, suggesting improved diet and eating behaviors could improve health-related outcomes. One factor that might improve dietary habits in older adults is food-related inhibitory control. We tested whether food-related inhibitory control, as measured via behavioral data (response time, accuracy) and scalp-recorded event-related potentials (ERP; N2 and P3 components), differed between younger and older adults over age 55. Fifty-nine older adults (31 females [52.5%], M_age = 64, SD_age = 7.5) and 114 younger adults (82 females [71.9%], M_age = 20.8) completed two go/no-go tasks, one inhibiting to high-calorie stimuli and one inhibiting to low-calorie stimuli, while electroencephalogram (EEG) data were recorded. Older adults had slower overall response times than younger adults, but this was not specific to either food task. There was not a significant difference in accuracy between younger and older adults, but both groups' accuracy and response times were significantly better during the high-calorie task than the low-calorie task. For both the N2 and P3 ERP components, younger adults had larger no-go ERP amplitudes than older adults, but this effect was not food-specific, reflecting overall generalized lower inhibitory control processing in older adults. P3 amplitude for the younger adults demonstrated a specific food-related effect (greater P3 amplitude for high-calorie no-go than low-calorie no-go) that was not present for older adults. Findings support previous research demonstrating age-related differences in inhibitory control though those differences may not be specific to inhibiting towards food.

Recognition of unilateral lower limb movement based on EEG signals with ERP-PCA analysis

It has been confirmed that motor imagery (MI) and motor execution (ME) share a subset of mechanisms underlying motor cognition. In contrast to the well-studied laterality of upper limb movement, the laterality hypothesis of lower limb movement also exists, but it needs to be characterized by further investigation. This study used electroencephalographic (EEG) recordings of 27 subjects to compare the effects of bilateral lower limb movement in the MI and ME paradigms. Event-related potential (ERP) recorded was decomposed into meaningful and useful representatives of the electrophysiological components, such as N100 and P300. Principal components analysis (PCA) was used to trace the characteristics of ERP components temporally and spatially, respectively. The hypothesis of this study is that the functional opposition of unilateral lower limbs of MI and ME should be reflected in the different alterations of the spatial distribution of lateralized activity. Meanwhile, the significant ERP-PCA components of the EEG signals as identifiable feature sets were applied with support vector machine to identify left and right lower limb movement tasks. The average classification accuracy over all subjects is up to 61.85% for MI and 62.94% for ME. The proportion of subjects with significant results are 51.85% for MI and 59.26% for ME, respectively. Therefore, a potential new classification model for lower limb movement can be applied on brain computer interface (BCI) systems in the future.

The relationship between acute stress and neurophysiological and behavioral measures of food-related inhibitory control: An event-related potential (ERP) study

Stress influences many health-related behaviors including diet and nutrition intake, often resulting in increased calorie intake, fewer healthy eating behaviors, and poorer nutrition. Food intake is modulated by inhibitory control and has important implications for our physical, mental, and emotional health. Yet, little is known about the relationship between stress and food-related inhibitory control. We tested the influence of a short-term experimental stressor on behavioral and event-related potential (ERP; N2 and P3 components) measures of food-related inhibitory control. Ninety-seven healthy participants were randomly assigned to complete the Trier Social Stress Test (TSST) (n = 48, 27 females [52.9%]) or a neutral control condition (n = 49, 35 females [70%]) immediately followed by food-specific go/no-go and neutral go/no-go tasks while electroencephalogram (EEG) data were recorded. Stress levels were successfully manipulated, with heightened self-report and physiological measures (heart rate and systolic blood pressure) of the stress response in individuals who completed the TSST compared to control. As expected, the high calorie food-specific go/no-go task elicited larger N2 amplitude than the neutral task. N2 component amplitude was also significantly larger following the TSST relative to the control task. There were no significant between-group or task differences for P3 amplitude or behavioral measures. Findings suggest heightened N2 amplitude following psychological stress that is not specific to food or inhibition processes and may reflect heightened arousal following stress. Future research in individuals with overweight/obesity or experiencing chronic stress will further clarify the role of stress in food-related inhibitory control.

Cortical processing of speaker politeness: Tracking the dynamic effects of voice tone and politeness markers

Information in the tone of voice alters social impressions and underlying brain activity as listeners evaluate the interpersonal relevance of utterances. Here, we presented requests that expressed politeness distinctions through the voice (polite/rude) and explicit linguistic markers (half of the requests began with Please). Thirty participants performed a social perception task (rating friendliness) while their electroencephalogram was recorded. Behaviorally, vocal politeness strategies had a much stronger influence on the perceived friendliness than the linguistic marker. Event-related potentials revealed rapid effects of (im)polite voices on cortical activity prior to ~300 ms; P200 amplitudes increased for polite versus rude voices, suggesting that the speaker's polite stance was registered as more salient in our task. At later stages, politeness distinctions encoded by the speaker's voice and their use of Please interacted, modulating activity in the N400 (300-500 ms) and late positivity (600-800 ms) time windows. Patterns of results suggest that initial attention deployment to politeness cues is rapidly influenced by the motivational significance of a speaker's voice. At later stages, processes for integrating vocal and lexical information resulted in increased cognitive effort to reevaluate utterances with ambiguous/contradictory cues. The potential influence of social anxiety on the P200 effect is also discussed.

Electrophysiological evidence for the coexistence of expectancy fulfillment and semantic integration during the processing of binding and compound nouns

This study employed electrophysiological measures to investigate the processes of expectancy fulfillment and semantic integration during the processing of binding and compound nouns in Chinese. Sequential expectancy and cloze probability between the two constituents of a two-character noun were manipulated in two experiments, resulting in four types of target characters (i.e., the final characters of two-character nouns): (i) high-cloze, binding character (HB); (ii) high-cloze, compound character (HC); (iii) low-cloze, binding character (LB); (iv) low-cloze, compound character (LC). Participants were asked to judge as quickly and accurately as possible whether the two characters, presented sequentially, formed a real word. The two experiments varied in stimulus onset asynchrony (SOA) between the initial and the target characters: 1000 ms and 300 ms. ERPs acquired at the target characters revealed a significant semantic integration effect in both experiments whereby low-cloze target characters elicited more negative-going activities than high-cloze target characters (L > H) with both long and short SOAs. Importantly, there was a graded N400 effect (LC = LB > HC > HB) at the central region: a clearly visible positive deflection for HB relative to HC in synchrony with an equivalence in negativity for LB and LC. This graded pattern was observed with an SOA of 1000 ms but not 300 ms. These results are discussed in terms of the possible coexistence of an expectancy fulfillment mechanism indexed by the P300 that monitors incoming information for realization of expectancies based on stored mental representations and a semantic integration mechanism indexed by the N400 that incorporates incoming information into the preceding context based on semantic-pragmatic knowledge. Manifestation of this coexistence appears sensitive to SOA-modulated attention orientation.

The Association Between Experimentally Induced Stress, Performance Monitoring, and Response Inhibition: An Event-Related Potential (ERP) Analysis

Psychological stress is increasingly associated with alterations in performance and affect. Yet, the relationship between experimentally induced psychological stress and neural indices of performance monitoring and error processing, as well as response inhibition, are unclear. Using scalp-recorded event-related potentials (ERPs), we tested the relationship between experimental stress, using the Trier Social Stress Test (TSST), and the error-related negativity (ERN), error positivity (Pe), and N2 ERP components. A final sample of 71 undergraduate students were randomly assigned to go through the TSST (n = 36; 18 female) or a brief mindfulness relaxation exercise (n = 35; 16 female) immediately followed by a go/no-go task while electroencephalogram (EEG) data were collected. Salivary cortisol, heart rate, and blood pressure confirmed increased physiological stress in the TSST group relative to control. Reaction times, accuracy, and post-error slowing did not differ by stress group. Two-group (TSST, control) by 2-trial type (correct, incorrect for ERN/Pe; go correct, no-go correct for N2) repeated measures ANOVAs for the ERN, Pe, and N2 showed the expected main effects of trial type; neither the ERN nor the N2 ERP components showed interactions with the stress manipulation. In contrast, the Pe component showed a significant Group by Trial interaction, with reduced Pe amplitude following the stress condition relative to control. Pe amplitude did not, however, correlate with cortisol reactivity. Findings suggest a reduction in Pe amplitude following experimental stress that may be associated with reduced error awareness or attention to errors following the TSST. Given the variability in the extant literature on the relationship between experimentally induced stress and neurophysiological reflections of performance monitoring, we provide another point of data and conclude that better understanding of moderating variables is needed followed by high-powered replication studies to get at the nuance that is not yet understood in the relationship between induced stress and performance monitoring/response inhibition processes.

Multimodal feature binding in object memory retrieval using event-related potentials: Implications for models of semantic memory

To test the hypothesis that semantic processes are represented in multiple subsystems, we recorded electroencephalogram (EEG) as we elicited object memories using the modified Semantic Object Retrieval Test, during which an object feature, presented as a visual word [VW], an auditory word [AW], or a picture [Pic], was followed by a second feature always presented as a visual word. We performed both hypothesis-driven and data-driven analyses using event-related potentials (ERPs) time locked to the second stimulus. We replicated a previously reported left fronto-temporal ERP effect (750-1000 ms post-stimulus) in the VW task, and also found that this ERP component was only present during object memory retrieval in verbal (VW, AW) as opposed to non-verbal (Pic) stimulus types. We also found a right temporal ERP effect (850-1000 ms post-stimulus) that was present in auditory (AW) but not in visual (VW, Pic) stimulus types. In addition, we found an earlier left temporo-parietal ERP effect between 350 and 700 ms post-stimulus and a later midline parietal ERP effect between 700 and 1100 ms post-stimulus, present in all stimulus types, suggesting common neural mechanisms for object retrieval processes and object activation, respectively. These findings support multiple semantic subsystems that respond to varying stimulus modalities, and argue against an ultimate unitary amodal semantic analysis.

Dissociable effects of prediction and integration during language comprehension: evidence from a large-scale study using brain potentials

Composing sentence meaning is easier for predictable words than for unpredictable words. Are predictable words genuinely predicted, or simply more plausible and therefore easier to integrate with sentence context? We addressed this persistent and fundamental question using data from a recent, large-scale (n = 334) replication study, by investigating the effects of word predictability and sentence plausibility on the N400, the brain's electrophysiological index of semantic processing. A spatio-temporally fine-grained mixed-effect multiple regression analysis revealed overlapping effects of predictability and plausibility on the N400, albeit with distinct spatio-temporal profiles. Our results challenge the view that the predictability-dependent N400 reflects the effects of either prediction or integration, and suggest that semantic facilitation of predictable words arises from a cascade of processes that activate and integrate word meaning with context into a sentence-level meaning. This article is part of the theme issue 'Towards mechanistic models of meaning composition'.

Linguistic Focus Promotes the Ease of Discourse Integration Processes in Reading Comprehension: Evidence From Event-Related Potentials

Psycholinguistic studies of focus processing have yielded varying results regarding how focus affects language processing. We report the results of an event-related potential (ERP) experiment that used question-answer pairs in a discourse to manipulate whether a target word was contextually focused, contrastively focused, contextually defocused, or contextually neutral. We found a negative-going waveform that was sustained in the time-course (250–800 ms after the target word onset) with a maximum over frontal-central scalp sites. As the structure of the discourse made the target word more focused, the negative-going deflection was systematically reduced. We also observed a frontal positive-going waveform that was larger for the focus-marked words relative to the neutral target word in an earlier time window (150–250 ms, P200), which may reflect increased attention allocated to the focused items. We propose that the reduced negative ERPs for the focused words reflects facilitation of meaning integration when focus functions to establish reference in the discourse representation. This can be attributed to extra attention paid to the focus-marked items that in turn promotes the prominence of focus-marked referent and prompts the contextual priming mechanism that facilitates the access of propositionally relevant items in text memory during reading.

Word-to-text integration: ERP evidence for semantic and orthographic effects in Chinese

Although writing systems affect reading at the level of word identification, one expects writing system to have minimal effects on comprehension processes. We tested this assumption by recording ERPs while native Chinese speakers read short texts for comprehension in the word-to-text integration (WTI) paradigm to compare with studies of English using this paradigm. Of interest was the ERP on a 2-character word that began the second sentence of the text, with the first sentence varied to manipulate co-reference with the critical word in the second sentence. A paraphrase condition in which the critical word meaning was coreferential with a word in the first sentence showed a reduced N400 reduction. Consistent with results in English, this N400 effect suggests immediate integration of a Chinese 2-character word with the meaning of the text. Chinese allows an additional test of a morpheme effect when one character of a two-character word is repeated across the sentence boundary, thus having both orthographic and meaning overlap. This shared morpheme condition showed no effect during the timeframe when orthographic effects are observed (e.g. N200), nor did it show an N400 effect. However, character repetition did produce an N400 reduction on parietal sites regardless it represented the same morpheme or a different one. The results indicate that the WTI integration effect is general across writing systems at the meaning level, but that the orthographic form nonetheless has an effect, and is specifically functional in Chinese reading.

Conflict and performance monitoring throughout the lifespan: An event-related potential (ERP) and temporospatial component analysis

Cognitive control includes higher-level cognitive processes used to evaluate environmental conflict. Given the importance of cognitive control in regulating behavior, understanding the developmental course of these processes may contribute to a greater understanding of normal and abnormal development. We examined behavioral (response times [RTs], error rates) and event-related potential data (N2, error-related negativity [ERN], correct-response negativity [CRN], error positivity [Pe]) during a flanker task in cross-sectional groups of 45 youth (ages 8-18), 52 younger adults (ages 20-28), and 58 older adults (ages 56-91). Younger adults displayed the most efficient processing, including significantly reduced CRN and N2 amplitude, increased Pe amplitude, and significantly better task performance than youth or older adults (e.g., faster RTs, fewer errors). Youth displayed larger CRN and N2, attenuated Pe, and significantly worse task performance than younger adults. Older adults fell either between youth and younger adults (e.g., CRN amplitudes, N2 amplitudes) or displayed neural and behavioral performance that was similar to youth (e.g., Pe amplitudes, error rates). These findings point to underdeveloped neural and cognitive processes early in life and reduced efficiency in older adulthood, contributing to poor implementation and modulation of cognitive control in response to conflict. Thus, cognitive control processing appears to reach peak performance and efficiency in younger adulthood, marked by improved task performance with less neural activation.

The relationship between brain reaction and English reading tests for non-native English speakers

This research analyzed the brain activity of non-native English speakers while engaged in English reading tests. The brain wave event-related potentials (ERPs) of participants were used to analyze the difference between making correct and incorrect choices on English reading test items. Three English reading tests of differing levels were designed and 20 participants, 10 males and 10 females whose ages ranged from 20 to 24, voluntarily participated in the experiment. Experimental results were analyzed by performing independent t-tests on the ERPs of participants for gender, difficulty level, and correct versus wrong options. Participants who chose incorrect options elicited a larger N600, verifying results found in the literature. Another interesting result was found: For incorrectly answered items, different areas of brain showing a significant difference in ERPs between the chosen and non-chosen options corresponded to gender differences; for males, this area was located in the right hemisphere whereas for females, it was located in the left. Experimental results imply that non-native English speaking males and females employ different areas of the brain to comprehend the meaning of difficult items.

The Effects of Acute Dopamine Precursor Depletion on the Cognitive Control Functions of Performance Monitoring and Conflict Processing: An Event-Related Potential (ERP) Study

Studies using medications and psychiatric populations implicate dopamine in cognitive control and performance monitoring processes. However, side effects associated with medication or studying psychiatric groups may confound the relationship between dopamine and cognitive control. To circumvent such possibilities, we utilized a randomized, double-blind, placebo-controlled, within-subjects design wherein participants were administered a nutritionally-balanced amino acid mixture (BAL) and an amino acid mixture deficient in the dopamine precursors tyrosine (TYR) and phenylalanine (PHE) on two separate occasions. Order of sessions was randomly assigned. Cognitive control and performance monitoring were assessed using response times (RT), error rates, the N450, an event-related potential (ERP) index of conflict monitoring, the conflict slow potential (conflict SP), an ERP index of conflict resolution, and the error-related negativity (ERN) and error positivity (Pe), ERPs associated with performance monitoring. Participants were twelve males who completed a Stroop color-word task while ERPs were collected four hours following acute PHE and TYR depletion (APTD) or balanced (BAL) mixture ingestion in two separate sessions. N450 and conflict SP ERP amplitudes significantly differentiated congruent from incongruent trials, but did not differ as a function of APTD or BAL mixture ingestion. Similarly, ERN and Pe amplitudes showed significant differences between error and correct trials that were not different between APTD and BAL conditions. Findings indicate that acute dopamine precursor depletion does not significantly alter cognitive control and performance monitoring ERPs. Current results do not preclude the role of dopamine in these processes, but suggest that multiple methods for dopamine-related hypothesis testing are needed.

Neuromagnetic brain activities associated with perceptual categorization and sound-content incongruency: a comparison between monosyllabic words and pitch names

In human cultures, the perceptual categorization of musical pitches relies on pitch-naming systems. A sung pitch name concurrently holds the information of fundamental frequency and pitch name. These two aspects may be either congruent or incongruent with regard to pitch categorization. The present study aimed to compare the neuromagnetic responses to musical and verbal stimuli for congruency judgments, for example a congruent pair for the pitch C4 sung with the pitch name do in a C-major context (the pitch-semantic task) or for the meaning of a word to match the speaker’s identity (the voice-semantic task). Both the behavioral data and neuromagnetic data showed that congruency detection of the speaker’s identity and word meaning was slower than that of the pitch and pitch name. Congruency effects of musical stimuli revealed that pitch categorization and semantic processing of pitch information were associated with P2m and N400m, respectively. For verbal stimuli, P2m and N400m did not show any congruency effect. In both the pitch-semantic task and the voice-semantic task, we found that incongruent stimuli evoked stronger slow waves with the latency of 500–600 ms than congruent stimuli. These findings shed new light on the neural mechanisms underlying pitch-naming processes.

Semantic brain areas are involved in gesture comprehension: An electrical neuroimaging study

While the mechanism of sign language comprehension in deaf people has been widely investigated, little is known about the neural underpinnings of spontaneous gesture comprehension in healthy speakers. Bioelectrical responses to 800 pictures of actors showing common Italian gestures (e.g., emblems, deictic or iconic gestures) were recorded in 14 persons. Stimuli were selected from a wider corpus of 1122 gestures. Half of the pictures were preceded by an incongruent description. ERPs were recorded from 128 sites while participants decided whether the stimulus was congruent. Congruent pictures elicited a posterior P300 followed by late positivity, while incongruent gestures elicited an anterior N400 response. N400 generators were investigated with swLORETA reconstruction. Processing of congruent gestures activated face- and body-related visual areas (e.g., BA19, BA37, BA22), the left angular gyrus, mirror fronto/parietal areas. The incongruent-congruent contrast particularly stimulated linguistic and semantic brain areas, such as the left medial and the superior temporal lobe.

Cognitive control of conscious error awareness: error awareness and error positivity (Pe) amplitude in moderate-to-severe traumatic brain injury (TBI)

Poor awareness has been linked to worse recovery and rehabilitation outcomes following moderate-to-severe traumatic brain injury (M/S TBI). The error positivity (Pe) component of the event-related potential (ERP) is linked to error awareness and cognitive control. Participants included 37 neurologically healthy controls and 24 individuals with M/S TBI who completed a brief neuropsychological battery and the error awareness task (EAT), a modified Stroop go/no-go task that elicits aware and unaware errors. Analyses compared between-group no-go accuracy (including accuracy between the first and second halves of the task to measure attention and fatigue), error awareness performance, and Pe amplitude by level of awareness. The M/S TBI group decreased in accuracy and maintained error awareness over time; control participants improved both accuracy and error awareness during the course of the task. Pe amplitude was larger for aware than unaware errors for both groups; however, consistent with previous research on the Pe and TBI, there were no significant between-group differences for Pe amplitudes. Findings suggest possible attention difficulties and low improvement of performance over time may influence specific aspects of error awareness in M/S TBI.

N400 brain responses to spoken phrases paired with photographs of scenes: implications for visual scene displays in AAC systems

Augmentative and alternative communication (AAC) systems are often implemented for individuals whose speech cannot meet their full communication needs. One type of aided display is called a Visual Scene Display (VSD). VSDs consist of integrated scenes (such as photographs) in which language concepts are embedded. Often, the representations of concepts on VSDs are perceptually similar to their referents. Given this physical resemblance, one may ask how well VSDs support development of symbolic functioning. We used brain imaging techniques to examine whether matches and mismatches between the content of spoken messages and photographic images of scenes evoke neural activity similar to activity that occurs to spoken or written words. Electroencephalography (EEG) was recorded from 15 college students who were shown photographs paired with spoken phrases that were either matched or mismatched to the concepts embedded within each photograph. Of interest was the N400 component, a negative deflecting wave 400 ms post-stimulus that is considered to be an index of semantic functioning. An N400 response in the mismatched condition (but not the matched) would replicate brain responses to traditional linguistic symbols. An N400 was found, exclusively in the mismatched condition, suggesting that mismatches between spoken messages and VSD-type representations set the stage for the N400 in ways similar to traditional linguistic symbols.

ERP signs of categorical and supra-categorical processing of visual information

BACKGROUND

The aim of the present study was to investigate to what extent shared and distinct brain mechanisms are possibly subserving the processing of visual supra-categorical and categorical knowledge as observed with event-related potentials of the brain. Access time to these knowledge types was also investigated. Picture pairs of animals, objects, and mixed types were presented. Participants were asked to decide whether each pair contained pictures belonging to the same category (either animals or man-made objects) or to different categories by pressing one of two buttons. Response accuracy and reaction times (RTs) were also recorded.

RESULTS

Both ERPs and RTs were grand-averaged separately for the same-different supra-categories and the animal-object categories. Behavioral performance was faster for more endomorphic pairs, i.e., animals vs. objects and same vs. different category pairs. For ERPs, a modulation of the earliest C1 and subsequent P1 responses to the same vs. different supra-category pairs, but not to the animal vs. object category pairs, was found. This finding supports the view that early afferent processing in the striate cortex can be boosted as a by-product of attention allocated to the processing of shapes and basic features that are mismatched, but not to their semantic quintessence, during same-different supra-categorical judgment. Most importantly, the fact that this processing accrual occurred independent of a traditional experimental condition requiring selective attention to a stimulus source out of the various sources addressed makes it conceivable that this processing accrual may arise from the attentional demand deriving from the alternate focusing of visual attention within and across stimulus categorical pairs' basic structural features. Additional posterior ERP reflections of the brain more prominently processing animal category and same-category pairs were observed at the N1 and N2 levels, respectively, as well as at a late positive complex level, overall most likely related to different stages of analysis of the greater endomorphy of these shape groups. Conversely, an enhanced fronto-central and fronto-lateral N2 as well as a centro-parietal N400 to man-made objects and different-category pairs were found, possibly indexing processing of these entities' lower endomorphy and isomorphy at the basic features and semantic levels, respectively.

CONCLUSION

Overall, the present ERP results revealed shared and distinct mechanisms of access to supra-categorical and categorical knowledge in the same way in which shared and distinct neural representations underlie the processing of diverse semantic categories. Additionally, they outlined the serial nature of categorical and supra-categorical representations, indicating the sequential steps of access to these separate knowledge types.

Word-to-text integration: Message level and lexical level influences in ERPs

Although the reading of connected text proceeds in a largely incremental fashion, the relative degree to which message level and lexical level factors contribute to integration processes across sentences remains an open question. We examined the influence of both factors on single words using event-related potentials (ERPs). Word pairs with either strong or weak forward association strength were critical items: embedded as coreferential words within two-sentence passages in a text comprehension task, and as isolated word pairs in a word meaning judgment task. While the N400 ERP component reflected an effect of forward association strength on lexico-semantic processing in the word task (i.e., reduced N400 amplitudes were seen for strongly associated pairs relative to weakly associated pairs), in the comprehension task, passages embedded with any associated word pairs elicited reduced N400 amplitudes relative to coherent baseline passages lacking one of the critical words. These comprehension effects reflect responses from the highest skilled comprehenders. The results demonstrate the effects of message level factors, and reading abilities, on the processing of single words.

Age-related changes in feature-based object memory retrieval as measured by event-related potentials

To investigate neural mechanisms that support semantic functions in aging, we recorded scalp EEG during an object retrieval task in 22 younger and 22 older adults. The task required determining if a particular object could be retrieved when two visual words representing object features were presented. Both age groups had comparable accuracy although response times were longer in older adults. In both groups a left fronto-temporal negative potential occurred at around 750ms during object retrieval, consistent with previous findings (Brier, Maguire, Tillman, Hart, & Kraut, 2008). In only older adults, a later positive frontal potential was found peaking between 800 and 1000ms during no retrieval. These findings suggest younger and older adults employ comparable neural mechanisms when features clearly facilitate retrieval of an object memory, but when features yield no retrieval, older adults use additional neural resources to engage in a more effortful and exhaustive search prior to making a decision.

Real-time processing in picture naming in adults who stutter: ERP evidence

OBJECTIVE

The aim was to compare real-time language/cognitive processing in picture naming in adults who stutter (AWS) versus typically-fluent adults (TFA).

METHODS

Participants named pictures preceded by masked prime words. Primes and target picture labels were identical or mismatched. Priming effects on naming and picture-elicited ERP activity were analyzed. Vocabulary knowledge correlations with these measures were assessed.

RESULTS

Priming improved naming RTs and accuracy in both groups. RTs were longer for AWS, and correlated positively with receptive vocabulary in TFA. Electrophysiologically, posterior-P1 amplitude negatively correlated with expressive vocabulary in TFA versus receptive vocabulary in AWS. Frontal/temporal-P1 amplitude correlated positively with expressive vocabulary in AWS. Identity priming enhanced frontal/posterior-N2 amplitude in both groups, and attenuated P280 amplitude in AWS. N400 priming was topographically-restricted in AWS.

CONCLUSIONS

Results suggest that conceptual knowledge was perceptually-grounded in expressive vocabulary in TFA versus receptive vocabulary in AWS. Poorer expressive vocabulary in AWS was potentially associated with greater suppression of irrelevant conceptual information. Priming enhanced N2-indexed cognitive control and visual attention in both groups. P280-indexed focal attention attenuated with priming in AWS only. Topographically-restricted N400 priming suggests that lemma/word form connections were weaker in AWS.

SIGNIFICANCE

Real-time language/cognitive processing in picture naming operates differently in AWS.

Adaptation to emotional conflict: evidence from a novel face emotion paradigm

The preponderance of research on trial-by-trial recruitment of affective control (e.g., conflict adaptation) relies on stimuli wherein lexical word information conflicts with facial affective stimulus properties (e.g., the face-Stroop paradigm where an emotional word is overlaid on a facial expression). Several studies, however, indicate different neural time course and properties for processing of affective lexical stimuli versus affective facial stimuli. The current investigation used a novel task to examine control processes implemented following conflicting emotional stimuli with conflict-inducing affective face stimuli in the absence of affective words. Forty-one individuals completed a task wherein the affective-valence of the eyes and mouth were either congruent (happy eyes, happy mouth) or incongruent (happy eyes, angry mouth) while high-density event-related potentials (ERPs) were recorded. There was a significant congruency effect and significant conflict adaptation effects for error rates. Although response times (RTs) showed a significant congruency effect, the effect of previous-trial congruency on current-trial RTs was only present for current congruent trials. Temporospatial principal components analysis showed a P3-like ERP source localized using FieldTrip software to the medial cingulate gyrus that was smaller on incongruent than congruent trials and was significantly influenced by the recruitment of control processes following previous-trial emotional conflict (i.e., there was significant conflict adaptation in the ERPs). Results show that a face-only paradigm may be sufficient to elicit emotional conflict and suggest a system for rapidly detecting conflicting emotional stimuli and subsequently adjusting control resources, similar to cognitive conflict detection processes, when using conflicting facial expressions without words.

An electrophysiological investigation of interhemispheric transfer time in children and adolescents with high-functioning autism spectrum disorders

Little is known about the functional impact of putative deficits in white-matter connectivity across the corpus callosum (CC) in individuals with autism spectrum disorders (ASDs). We utilized the temporal sensitivity of event-related potentials to examine the interhemispheric transfer time (IHTT) of basic visual information across the CC in youth with high-functioning ASD relative to healthy controls. We conducted two experiments: a visual letter matching experiment (n = 46) and a visual picture matching experiment, (n = 48) and utilized both electrophysiological (N1 and P1 amplitudes and latencies) and behavioral [response times (RTs), error rates] indices of IHTT. There were no significant group differences on either experiment for RTs, error rates, or N1 and P1 latencies, suggesting that on basic tasks the timing of information flow across the CC may not be altered in high functioning ASD.

MUC (Memory, Unification, Control) and beyond

A neurobiological model of language is discussed that overcomes the shortcomings of the classical Wernicke-Lichtheim-Geschwind model. It is based on a subdivision of language processing into three components: Memory, Unification, and Control. The functional components as well as the neurobiological underpinnings of the model are discussed. In addition, the need for extension of the model beyond the classical core regions for language is shown. The attention network and the network for inferential processing are crucial to realize language comprehension beyond single word processing and beyond decoding propositional content. It is shown that this requires the dynamic interaction between multiple brain regions.

The impact of a brief mindfulness meditation intervention on cognitive control and error-related performance monitoring

Meditation is associated with positive health behaviors and improved cognitive control. One mechanism for the relationship between meditation and cognitive control is changes in activity of the anterior cingulate cortex-mediated neural pathways. The error-related negativity (ERN) and error positivity (Pe) components of the scalp-recorded event-related potential (ERP) represent cingulate-mediated functions of performance monitoring that may be modulated by mindfulness meditation. We utilized a flanker task, an experimental design, and a brief mindfulness intervention in a sample of 55 healthy non-meditators (n = 28 randomly assigned to the mindfulness group and n = 27 randomly assigned to the control group) to examine autonomic nervous system functions as measured by blood pressure and indices of cognitive control as measured by response times, error rates, post-error slowing, and the ERN and Pe components of the ERP. Systolic blood pressure significantly differentiated groups following the mindfulness intervention and following the flanker task. There were non-significant differences between the mindfulness and control groups for response times, post-error slowing, and error rates on the flanker task. Amplitude and latency of the ERN did not differ between groups; however, amplitude of the Pe was significantly smaller in individuals in the mindfulness group than in the control group. Findings suggest that a brief mindfulness intervention is associated with reduced autonomic arousal and decreased amplitude of the Pe, an ERP associated with error awareness, attention, and motivational salience, but does not alter amplitude of the ERN or behavioral performance. Implications for brief mindfulness interventions and state vs. trait affect theories of the ERN are discussed. Future research examining graded levels of mindfulness and tracking error awareness will clarify relationship between mindfulness and performance monitoring.

What are the influences of orthogonally-manipulated valence and arousal on performance monitoring processes? The effects of affective state

Studies of the influence of affective state on the cognitive control process of performance monitoring are mixed and few studies have orthogonally manipulated affective valence and arousal. Performance monitoring can be measured using behaviors (e.g., response times and error rates) and components of the event-related potentials (ERPs), such as the error-related negativity (ERN), correct-related negativity (CRN), and post-error positivity (Pe). We used a pre/post design and standard mood induction paradigm in 121 healthy participants randomly assigned to orthogonal valence (positive or negative) and arousal (high or low) conditions (i.e., happy, calm, anxious, or sad mood states). Following mood induction, valence and arousal ratings differed between groups. Behavioral findings showed decreased accuracy in participants with high arousal and negative valence (i.e., anxious condition), but no additional response time (RT), post-error slowing, or accuracy effects. Amplitude of the CRN differentiated high and low valence, but was not related to arousal. Positive valence was associated with decreased CRN amplitude even when baseline affect and demographic variables were controlled. Valence and arousal did not significantly differentiate the amplitude of the ERN, although the ERN minus CRN difference was related to arousal but not valence ratings in multiple regression analyses. Affect-related differences were not shown for the Pe. Findings provide a context to understand how dimensional aspects of emotional valence and arousal influence performance-monitoring processes and suggest a need for further research on the functional role of the CRN and its relation to affective valence.

Potential risk for healthy siblings to develop schizophrenia: evidence from pattern classification with whole-brain connectivity

Recent resting-state functional connectivity MRI studies using group-level statistical analysis have demonstrated the inheritable characters of schizophrenia. The objective of the present study was to use pattern classification as a means to investigate schizophrenia inheritance based on the whole-brain resting-state functional connectivity at the individual subject level. One-against-one pattern classifications were made amongst three groups (i.e. patients diagnosed with schizophrenia, healthy siblings, and healthy controls after preprocessing), resulting in an 80.4% separation between patients with schizophrenia and healthy controls, a 77.6% separation between schizophrenia patients and their healthy siblings, and a 78.7% separation between healthy siblings and healthy controls, respectively. These results suggest that the healthy siblings of schizophrenia patients have an altered resting-state functional connectivity pattern compared with healthy controls. Thus, healthy siblings may have a potential higher risk for developing schizophrenia compared with the general population. Moreover, this pattern differed from that of schizophrenia patients and may contribute to the normal behavior exhibition of healthy siblings in daily life.

Temporospatial dissociation of Pe subcomponents for perceived and unperceived errors

Previous research on performance monitoring revealed that errors are followed by an initial fronto-central negative deflection (error-related negativity, ERN or Ne) and a subsequent centro-parietal positivity (error positivity, Pe). It has been shown that error awareness mainly influences the Pe, whereas the ERN seems unaffected by conscious awareness of an error. The aim of the present study was to investigate the relation of ERN and Pe to error awareness in a visual size discrimination task in which errors are not elicited by impulsive responding but by perceptual difficulty. Further, we applied a temporospatial principal component analysis (PCA) to examine whether the temporospatial subcomponents of the Pe would differentially relate to error awareness. Event-related potential (ERP) results were in accordance with earlier studies: a significant error awareness effect was found for the Pe, but not for the ERN. Interestingly, a modulation with error perception on correct trials was found: correct responses considered as incorrect had larger correct-related negativity (CRN) and lager Pe amplitudes than correct responses considered as correct. The PCA yielded two relevant spatial factors accounting for the Pe (latency 300 ms). A temporospatial factor characterized by a centro-parietal positivity varied significantly with error awareness. Of the two temporospatial factors corresponding to ERN and CRN, one factor with central topography varied with response correctness and subjective error perception on correct responses. The PCA results indicate that the error awareness effect is specifically related to the centro-parietal subcomponent of the Pe. Since this component has also been shown to be related to the importance of an error, the present variation with error awareness indicates that this component is sensitive to the salience of an error and that salience secondarily may trigger error awareness.

Cognitive control and conflict adaptation in youth with high-functioning autism

BACKGROUND

  Youth diagnosed with autism spectrum disorders (ASD) often show deficits in cognitive control processes, potentially contributing to characteristic difficulties monitoring and regulating behavior. Modification of performance following conflict can be measured by examining conflict adaptation, the adjustment of cognitive resources based on previous-trial conflict. The electrophysiological correlates of these processes can be measured using the N2, a stimulus-locked component of the event-related potential (ERP).

METHODS

  High-density ERPs and behavioral data [i.e. response times (RTs) and error rates] were acquired while 28 youth with ASD and 36 typically developing controls completed a modified Eriksen flanker task.

RESULTS

  Behaviorally, groups showed similar conflict adaptation effects; youth with ASD showed larger RT slowing on switch trials. For electrophysiology, controls demonstrated larger N2 amplitudes for incongruent (high-conflict) trials following congruent (low-conflict) trials than for incongruent trials following incongruent trials. Importantly, youth with ASD showed no such differences in N2 amplitude based on previous-trial conflict.

CONCLUSIONS

  Lack of electrophysiological conflict adaptation effects in youth with ASD indicates irregular neural processing associated with conflict adaptation. Individuals with ASD show declines in level of conflict evaluation and adaptation. Future research is necessary to accurately characterize and understand the behavioral implications of these cognitive control deficits relative to diagnostic severity, anxiety, and personality.

Performance monitoring and cognitive control in individuals with mild traumatic brain injury

Literature suggests that individuals with mild traumatic brain injury (mTBI) show subtle abnormalities in the cognitive control process of performance monitoring. The neural bases of performance monitoring can be measured using the error-related negaitivity (ERN) and post-error positivity (Pe) components of the scalp-recorded event-related potential (ERP). Thirty-six individuals with mTBI and 46 demographically similar controls completed a modified color-naming Stroop task while ERPs were recorded. Separate repeated-measures analyses of variance were used to examine the behavioral (response times [RT] and error rates) and ERP (ERN and Pe amplitudes) indices of performance monitoring. Both groups showed slower RTs and increased error rates on incongruent trials relative to congruent trials. Likewise, both groups showed more negative ERN and more positive Pe amplitude to error trials relative to correct trials. Notably, there were no significant main effects or interactions of group for behavioral and ERP measures. Subgroup and correlational analyses with post-concussive symptoms and indices of injury severity were also not significant. Findings suggest comparable performance to non-injured individuals in some aspects of cognitive control in this sample. Neuropsychological implications and comparison with other cognitive control component processes in individuals with TBI are provided.

The time-course of single-word reading: evidence from fast behavioral and brain responses

We usually feel that we understand a familiar word “immediately”. However, even basic aspects of the time-line of word recognition are still controversial. Different domains of research have still not converged on a coherent account. An integration of multiple sources of information would lead to more strongly constrained theoretical models, and help finding optimal measures when monitoring specific aspects of word recognition impairments in patient groups. In our multimodal approach – combining fast behavioral measures, ERPs and EEG/MEG source estimation – we provide converging evidence for the latencies of earliest lexical and semantic information retrieval in visual word recognition. Participants performed lexical and semantic decisions (LD, SD) in a Go/NoGo paradigm. We introduced eye-blink latencies as a dependent variable, in order to measure behavioral responses that are faster and less variable than traditional button presses. We found that the earliest behavioral responses distinguishing stimulus categories can occur around 310 ms. Ex-Gaussian analysis of behavioral responses did not reveal reliable differences between LD and SD. The earliest ERP differences between Go and NoGo conditions occurred around 160 ms for both LD and SD. Distributed source analysis of combined EEG/MEG data estimated neuronal generators for the lexicality effect around 200 ms in the left anterior middle temporal lobe. Thus, behavior and brain responses provide coherent evidence that the brain starts retrieving lexical and semantic information near-simultaneously within 200 ms of word onset. Our results support models of word recognition that assume a continuous accumulation of task-related information from the stimulus, which might be described by Bayesian principles.

Structural integrity of the prefrontal cortex modulates electrocortical sensitivity to reward

The P300 is a known ERP component assessing stimulus value, including the value of a monetary reward. In parallel, the incentive value of reinforcers relies on the PFC, a major cortical projection region of the mesocortical reward pathway. Here we show a significant positive correlation between P300 response to money (vs. no money) with PFC gray matter volume in the OFC, ACC, and dorsolateral and ventrolateral PFC in healthy control participants. In contrast, individuals with cocaine use disorders showed compromises in both P300 sensitivity to money and PFC gray matter volume in the ventrolateral PFC and OFC and their interdependence. These results document for the first time the importance of gray matter structural integrity of subregions of PFC to the reward-modulated P300 response.