Differences In Event-related Potentials Research Articles

The influence of signal strength on conscious and nonconscious neural processing of emotional faces

Abstract Consciously perceived emotional relative to neutral facial expressions evoke stronger early and late event-related potential (ERP) components. However, the extent of nonconscious neural processing of emotional information in faces is still a matter of debate. One possible reason for conflicting findings might relate to threshold effects depending on the sensory strength of stimuli. In the current study, we investigated this issue by manipulating the contrast of fearful and neutral faces presented with or without continuous flash suppression (CFS). Low, medium, and high contrasts were calibrated individually so that faces were consciously perceived at all contrast levels if presented without CFS. With CFS, however, low- and medium-contrast faces remained nonconscious, while high-contrast faces broke the suppression. Without CFS, ERPs showed an increased early negativity and late positivity in response to fearful vs. neutral faces regardless of contrast. Under CFS, we observed differential early negativities for suppression-breaking high-contrast fearful vs. neutral faces. For nonconscious faces, however, the contrast level modulated the difference between fearful and neutral faces, showing enhanced early negativities only at medium contrast and an inverted effect at low contrast. Additional analysis of late positivities provided evidence for the absence of an effect at low and medium contrast, while at high-contrast, fearful faces elicited a larger positivity than neutral ones. Taken together, our findings demonstrate the significance of stimulus strength for nonconscious emotion processing under CFS, implying that early negative ERP differences between neutral and fearful faces depend on stimulus contrast near the detection threshold.

The Impact of Motivation on Sustained Attention in Very Preterm and Term-born Children: An ERP Study.

To compare the effect of motivational features on sustained attention in children born very preterm and at term. EEG was recorded while 34 8-to-11-year-old children born very preterm and 34 term-born peers completed two variants of a cued continuous performance task (CPT-AX); a standard CPT-AX with basic shape stimuli, and structurally similar motivating variant, with a storyline, familiar characters, and feedback. Higher hit rates, quicker response times and larger event-related potential (ERP) amplitudes were observed during the motivating, compared with the standard, task. Although groups did not differ in task performance, between-task differences in ERPs associated with orienting were larger in term-born than very preterm children. The findings add to previous evidence of disruption to the brain networks that support salience detection and selective attention in children born preterm. Manipulations that increase intrinsic motivation can promote sustained attention in both term-born and very preterm children.

Neural Processing of Speech Sounds in Autistic Kindergarteners as a Predictor of Reading Outcomes.

Phonology is an important foundation of reading development; however, little is known about the neural substrates of speech sound processing and reading development in autistic children. We investigated early auditory event-related potentials (ERPs) in response to speech sounds and their association with reading ability (word recognition and reading comprehension). 56 kindergarteners (28 ASD, 28 TD) completed an ERP task using rhyming, bisyllabic pseudowords (/gibu/ and /bidu/) in an old/new design: 50% "old" and 50% "new" stimuli presented following a sensitization block of 100% "old" stimuli. Behavioral measures of reading ability were completed at kindergarten entry and exit. Results from generalized linear mixed models revealed a significant three-way interaction between stimuli ("new" vs. "old"), diagnosis (ASD vs. TD), and reading ability (for word recognition and reading comprehension) for P1 and P2 amplitude. Follow-up analyses revealed that autistic children with lower reading abilities showed greater P1 and P2 amplitudes for "new" vs. "old" stimuli, with effects ranging from marginal to significant (p's 0.04-0.07). Regression analyses revealed that old/new ERP difference scores significantly predicted later word recognition at kindergarten year-end (P1 amplitude: p = .05; P2 amplitude: p = .04), but not reading comprehension, controlling for sex and nonverbal IQ. Autistic children with poorer reading skills, specifically those with weaker word recognition abilities, show neural differences when processing speech sounds compared to autistic peers with greater reading ability and typically developing children. A better understanding of the neural basis of speech sound processing could enhance our insight into the heterogeneity in reading among individuals with ASD and guide future treatment approaches.

Intraindividual Variability of Event-Related Potentials in Psychosis: A Registered Report

BackgroundNeurophysiological tools have yielded valuable insights into the pathophysiology and treatment of psychosis. However, studies using event-related potentials (ERPs) have primarily focused on mean scores and neglected the within-person variability of ERP scores. The neglect of within-person variability of ERPs in the search for biomarkers might have resulted in crucial differences related to psychosis being missed. In this registered report, we aimed to determine whether distinct patterns of intraindividual variability in ERP biomarkers would be observed in people with a lifetime psychosis diagnosis. MethodsPublicly available data posted to the National Institute of Mental Health Data Archive for 1R01MH110434-01 was obtained for 162 patients with a lifetime history of psychosis and 178 never-psychotic (NP) participants. Participants completed tasks that measured the auditory mismatch negativity (MMN), P300, error-related negativity, and reward positivity. Multilevel location-scale models were used to determine whether patients showed greater intraindividual variability of ERP scores than NP participants. ResultsContrary to predictions, the groups did not differ in within-person variability of MMN frequency, P300, or error-related negativity; patients showed less variability in MMN duration than NP participants. Exploratory analyses of a subset of patients with schizophrenia showed greater variability of MMN in this group than in the NP group. Greater severity of thought disorder and activation symptoms were associated with higher intraindividual MMN variability. ConclusionsDistinct patterns of intraindividual variability in the measured ERPs were not observed for the broad group of people with lifetime psychotic disorders. Exploratory analyses suggest that intraindividual differences in ERPs are more relevant to schizophrenia and certain symptom dimensions than to psychotic disorders broadly, but research is needed to confirm these exploratory findings.

Electrophysiology in the language classroom

Using electrophysiological methods, Second Language Acquisition researchers have uncovered significant information about the neural correlates of late-learned additional language (L2) processing. An overarching question in much of this research is whether L2 learners show ‘nativelike’ event-related potential (ERP) patterns for grammar and semantic processing. The conclusions from early work on this question indicated that L2 ERP patterns can change qualitatively over time, for example as L2 proficiency increases, and that L2 learners do tend to show ‘nativelike’ ERP responses for some linguistic structures, particularly at higher proficiency. Certainly, whether L2 learners can achieve native speaker-like processing and behaviour has implications for the L2 classroom. This paper presents a review of L2 ERP individual differences research on grammar and semantic processing and highlights implications for L2 research and teaching. We focus the review on recent work that has examined individual differences in L2 ERPs, an area of research that may be especially fruitful for advancing knowledge of L2 neurocognition in classroom learners.

Electrophysiological signatures of spelling sensitivity development from primary school age to adulthood

Recognizing spelling errors is important for correct writing and reading, and develops over an extended period. The neural bases of the development of orthographic sensitivity remain poorly understood. We investigated event-related potentials (ERPs) associated with spelling error recognition when performing the orthographic decision task with correctly spelled and misspelled words in children aged 8–10 years old, early adolescents aged 11–14 years old, and adults. Spelling processing in adults included an early stage associated with the initial recognition of conflict between orthography and phonology (reflected in the N400 time window) and a later stage (reflected in the P600 time window) related to re-checking the spelling. In children 8–10 years old, there were no differences in ERPs to correct and misspelled words; in addition, their behavioral scores were worse than those of early adolescents, implying that the ability to quickly recognize the correct spelling is just beginning to develop at this age. In early adolescents, spelling recognition was reflected only at the later stage, corresponding to the P600 component. At the behavioral level, they were worse than adults at recognizing misspelled words. Our data suggest that orthographic sensitivity can develop beyond 14 years.

Мозговые механизмы формирования понятий на основе исключительно зрительной модальности

Background. The problem of concept formation in the visual modality remains largely unexplored. There are many studies on the formation of verbal concepts in the learning process. However, it has not yet been fully investigated how concept formation occurs in conditions when both the signified and the signifier (sign) are represented only in the visual modality and what brain mechanisms are involved in this process. Objectives. The aim of the present work was to identify the brain mechanisms of visual concepts formation, on the basis of EEG registration with subsequent localization of the sources of electrical activity. Another task is to evaluate the possibility of actualizing the process of indirect learning in the formation of visual concepts. Study Participants. 26 Russian-speaking subjects without neurological disorders: 10 males and 16 females (aged 18 to 40 years, mean age 22.92 years, SD = 6.38) participated in the study. Methods. Chinese hieroglyphs, unfamiliar to the subjects, were taken as signs. The designated ones were emoticons (schematic faces expressing various emotions). A total of 10 pairs of stimuli sign-designated were presented. A 19-channel electroencephalogram (EEG) was recorded in three successive series: 1) the initial perception of hieroglyphic signs without assigning them a category; 2) categorization of these signs in the process of associative learning, with only 8 designating stimuli-signs directly associated with the designated stimulus, while 2 stimuli-signs were never associated with the stimulus-designator, their meaning was established indirectly; 3) subsequent perception of signs with the meaning already assigned to them. All stimuli were presented to the subjects visually. A new method of localization of brain activity, “Virtually implanted electrode”, developed by A.V. Vartanov (patent RU No. 2 785 268) was applied. Results. The analysis of the subjects' responses showed that during the learning process all signs (including those formed indirectly) were assigned a certain meaning (designated). Differences in event-related potentials (ERP) were found in leads C3 and CZ. Significant differences in ERP as a result of learning were revealed in a number of brain structures. It was found that a number of functional connections between the left area of the secondary visual cortex and the right part of the cerebellum changed significantly as a result of learning. Conclusions. The development of visual categories is ensured by the coordinated work of the right part of the cerebellum, parahippocampal gyrus and primary visual cortex, which is confirmed by the discovered differences in the corresponding ERPs.

The specificity of the auditory P300 responses and its association with clinical outcomes in youth with psychosis risk syndrome

BackgroundSchizophrenia often occurs in youth, and psychosis risk syndrome (PRS) occurs before the onset of psychosis. Assessing the neuropsychological abnormalities of PRS individuals can help in early identification and active intervention of mental illness. Auditory P300 amplitude defect is an important manifestation of attention processing abnormality in PRS, but it is still unclear whether there are abnormalities in the attention processing of rhythmic compound tone stimuli in PRS individuals, and whether the P300 amplitude induced by these stimuli is specific to PRS individuals and related to their clinical outcomes. MethodsIn total, 226 participants, including 122 patients with PRS, 51 patients with emotional disorders (ED), and 53 healthy controls (HC) were assessed. Baseline electroencephalography was recorded during the compound tone oddball task. The event-related potentials (ERPs) induced by rhythmic compound tone stimuli of two frequencies (20-Hz, 40-Hz) were measured. Almost all patients with PRS were followed up for 12 months and reclassified into four groups: PRS-conversion, PRS-symptomatic, PRS-emotional disorder, and PRS-complete remission. The differences in baseline ERPs were compared among the clinical outcome groups. ResultsRegardless of the stimulation frequency, the average P300 amplitude were significantly higher in patients with PRS than in those with ED (p = 0.003, d = 0.48) and in HC (p = 0.002, d = 0.44) group. The average P300 amplitude of PRS-conversion group was significantly higher than that of the PRS-complete remission (p = 0.016, d = 0.72) and HC group (p = 0.001, d = 0.76), and the average P300 amplitude of PRS-symptomatic group was significantly higher than that of the HC group (p = 0.006, d = 0.48). Regardless of the groups (PRS, ED, HC) or the PRS clinical outcome groups, the average P300 amplitude induced by 20-Hz tone stimulation was significantly higher than that induced by 40-Hz stimulation (ps < 0.001, Ƞ2 = 0.074–0.082). The average reaction times of PRS was significantly faster than that of ED (p = 0.01, d = 0.38), and the average reaction times of the participants to 20-Hz target stimulation was significantly faster than that to 40-Hz target stimulation (p < 0.001, d = 0.21). ConclusionThe auditory P300 amplitude induced by rhythmic compound tone stimuli is a specific electrophysiological manifestation of PRS, and the auditory P300 amplitude induced by compound tone stimuli shows promise as a putative prognostic biomarker for PRS clinical outcomes, including conversion to psychosis and clinical complete remission.

Visual Event-Related Potentials under External Emotional Stimuli as Early Signs for Mild Cognitive Impairment.

Alzheimer's disease (AD) is a neurodegenerative disorder featured by progressive cognitive decline, which manifests in severe impairment of memory, attention, emotional processing and daily activities, leading to significant disability and social burden. Investigation on Mild Cognitive Impairment (MCI), the prodromal and transitional stage between normal aging and AD, serves as a key in diagnosing and slowing down the progression of AD. Numerous effects have been made up to date, however, the attentional mechanisms under different external emotion stimuli in MCI and AD are still unexplored in deep. To further explore the attentional mechanisms under different external emotion stimuli in both MCI and AD patients. In 51 healthy volunteers (Controls, 24 males and 27 females), 52 MCI (19 males and 33 females), and 47 AD (15 males and 32 females) patients, we administered the visual oddball event-related potentials (ERPs) under three types of external emotional stimuli: Neutral, Happiness and Sadness, in which the components N1, P2, N2 and P3 as well as the abnormal cortical activations corresponding to the significant ERP differences in the three groups were observed. Under all three external emotions, in AD patients, N2 and P3 latencies were significantly prolonged compared to both Controls and MCI. In addition, under Happiness, in MCI, P3 latencies were significantly delayed compared to Controls. Meanwhile, under both Happiness and Sadness, in AD patients, P3 amplitudes were significantly decreased compared to Controls and MCI, respectively. During N2 time window, under Neutral emotion, significant hypoactivation in the right superior temporal gyrus was found in AD patients compared to Controls, and under Happiness, the activation of the right inferior frontal gyrus was significantly attenuated in MCI compared to Controls. Under Sadness, in AD patients, the activation of the right superior frontal gyrus was significantly decreased compared to MCI. During P3 time window, under both Happiness and Sadness, when AD patients compared to MCI, the significantly attenuated activations were located in the right fusiform gyrus and the right middle occipital gyrus, respectively. Our results demonstrated visual attentional deficits under external emotional stimuli in both MCI and AD patients, highlighting the function of Happiness for early detecting MCI, in which the P3 latency and the hypoactivation of right inferior frontal gyrus during N2 time window can be early signs. The current study sheds further light of attentional mechanisms in MCI and AD patients, and indicates the value of emotional processing in the early detection of cognitive dysfunction.

Processing of emotional connotations in Chinese monomorphic and compound words reflected by the early posterior negativity.

Writing stands as one of humanity's most profound inventions, facilitating the efficient sharing and transmission of vast amounts of information. Similar to images and facial expressions, visual (written) words possess the ability to evoke emotional connotations. Understanding how the brain perceives these emotional nuances encoded in highly symbolic visual words is a key focus of the emerging field of "affective neurolinguistics." At the core of this inquiry lies the examination of the early posterior negativity (EPN), an event-related potentials (ERPs) component peaking around 300 ms after stimulus onset in the occipitotemporal scalp region. EPN has consistently emerged in response to emotional stimuli, encompassing pictures, faces, and visual words. However, prior research has notably lacked observation of EPN in response to Chinese emotional words, raising questions about potential differences in emotional processing between Chinese and other languages. Given the logographic nature of the Chinese writing system and the prevalence of compound words in the Chinese lexicon, this study aims to explore whether the emotional processing of Chinese monomorphic and compound words elicits an EPN response. Two experiments were conducted: Experiment 1 utilized one-character words (monomorphic words), while Experiment 2 employed two-character words (compound words). Participants were assigned a go/no-go task, instructed to respond to unknown words (word recognition task) or blue stimuli (color decision task). Data analysis using a data-driven mass univariate approach revealed significant ERP differences between emotional and neutral words. Notably, the time course, scalp topography, and cortical generators of the difference ERP presented a characteristic EPN response in both experiments. These findings strongly support the notion that the processing of emotional connotations in both Chinese monomorphic and compound words is reflected by the EPN, paving the way for future research using EPN as an emotion-related ERP component for investigating emotional processing of Chinese words.

High - definition transcranial direct current stimulation (HD-tDCS) to the medial prefrontal cortex (mPFC) alleviates occupational gender stereotypes

Occupational gender stereotypes are widely held misconceptions that individuals use to classify occupations according to gender. Alleviating occupational gender stereotypes would be beneficial for individuals to choose occupations more freely, without the influence of gender-based expectations. Transcranial direct current stimulation (tDCS) has shown effectiveness in alleviating stereotypical beliefs. The present study aims to explore the positive effects of tDCS targeting the medial prefrontal cortex (mPFC) on occupational gender stereotypes and uses event-related potentials (ERPs) to investigate the neural correlates of tDCS in modulating occupational gender stereotypes. Participants (N = 60) were recruited and randomly assigned to either the anodal tDCS group (n = 30) or the sham tDCS group (n = 30). All participants were asked to complete the Implicit Association Test (IAT) in the pre- and post-stimulation, while EEG data were recorded simultaneously. The behavioral results showed a decreased D value and reaction time (RT) after the tDCS in the anodal group. However, no significant difference in ERPs were observed after tDCS between the two groups. This study contributes to our understanding of occupational gender stereotypes and provides further evidence supporting the use of tDCS. The findings highlight the importance of considering the mPFC in research on occupational gender stereotypes and pave the way for future investigations utilizing brain stimulation techniques to address stereotypes.

An ERP measure of non-conscious memory reveals dissociable implicit processes in human recognition using an open-source automated analytic pipeline.

Non-conscious processing of human memory has traditionally been difficult to objectively measure and thus understand. A prior study on a group of hippocampal amnesia (N = 3) patients and healthy controls (N = 6) used a novel procedure for capturing neural correlates of implicit memory using event-related potentials (ERPs): old and new items were equated for varying levels of memory awareness, with ERP differences observed from 400 to 800 ms in bilateral parietal regions that were hippocampal-dependent. The current investigation sought to address the limitations of that study by increasing the sample of healthy subjects (N = 54), applying new controls for construct validity, and developing an improved, open-source tool for automated analysis of the procedure used for equating levels of memory awareness. Results faithfully reproduced prior ERP findings of parietal effects that a series of systematic control analyses validated were not contributed to nor contaminated by explicit memory. Implicit memory effects extended from 600 to 1000 ms, localized to right parietal sites. These ERP effects were found to be behaviorally relevant and specific in predicting implicit memory response times, and were topographically dissociable from other traditional ERP measures of implicit memory (miss vs. correct rejections) that instead occurred in left parietal regions. Results suggest first that equating for reported awareness of memory strength is a valid, powerful new method for revealing neural correlates of non-conscious human memory, and second, behavioral correlations suggest that these implicit effects reflect a pure form of priming, whereas misses represent fluency leading to the subjective experience of familiarity.

Real‐time Neurofeedback Rewards Memory‐related Potentials in Older Brains

AbstractBackgroundElectroencephalogram (EEG)‐based neurofeedback (NF) allows reward of desired brain activity in milliseconds. Compared to frequency power‐based approach during resting state EEG, event‐related potentials (ERPs) based NF during a task is technically challenging because of the cost of computation over a time window. We have previously established that left‐frontal memory‐related potentials discriminate normal cognitive aging from age‐ and education‐ matched older adults with risk of mild cognitive impairment (MCI). To modulate brainwaves during working memory retrieval towards healthier patterns, we develop an ERP‐based neurofeedback protocol to reward better memory‐related potentials.MethodThe training protocol is developed based on a modified delayed match‐to‐sample task also known as Bluegrass working memory paradigm. During each memory trial, a participant holds the sample target image in his/her working memory and responds whether each subsequent image is a Match or Nonmatch to the memory target by pressing the button. Real‐time classification of extracted ERP features is analyzed after stimulus onset, the dynamic machine‐learning program then modifies the stimulus by turning it into vivid color (reward) or leaving it with black‐and‐white (unrewarded). The processing pipeline has been developed using ERPs of older adults with and without MCI. The left frontal sites (F3 and F7) were preprocessed by re‐referencing and filtering with a 0.05 – 40 Hz band‐pass filter. For each participant, the EEG of 5 offline base trials in a 300‐600ms time window was used as a baseline. The ERP difference of the baseline versus the subsequent single trial is calculated to determine whether the image will be colored or left at black‐and‐white.ResultOur newly developed ERP‐neurofeedback protocol has succeeded in providing visual feedback based on fluctuation of single trial ERP in real time. The program was also designed to fit in each individual due to varied sensibility to NF. Currently we are to examine the feasibility and effectiveness of the proposed protocol by measuring memory indicators before and after NF training sessions.ConclusionWe have developed a new protocol using ERP‐based neurofeedback to improve personalized memory retrieval. The program is the first step to intervention trials for enhancing successful memory by rewarding desired memory‐related potentials in older brains.

Investigating app icon recognition with event-related potentials.

In modern society, visual symbols such as logos, icons, and letters have become essential for communication and cognition, playing a crucial role in daily life. This study focuses on app icons, a frequently encountered type of symbol, and aims to investigate the neural mechanisms involved in their recognition. Specifically, our objective is to identify the timing and location of brain activity associated with this process. We presented participants with familiar and unfamiliar app icons and asked them to perform a repetition detection task while recording the event-related potentials (ERPs) elicited by these stimuli. Statistical analysis revealed a significant difference in the ERPs between familiar and unfamiliar icons, occurring around 220 ms in the parietooccipital scalp region. The source analysis indicated that this ERP difference originated in the ventral occipitotemporal cortex, specifically the fusiform gyrus. These findings suggest that the recognition of familiar app icons results in the activation of the ventral occipitotemporal cortex approximately 220 ms after exposure. Additionally, our findings, in conjunction with previous research on visual word recognition, suggest that the lexical orthographic processing of visual words is dependent on general visual processing mechanisms that are also involved in the recognition of familiar app icons. In essence, the ventral occipitotemporal cortex likely plays a crucial role in memorizing and recognizing visual symbols and objects, including familiar visual words.

Visual event-related potentials reveal the early whole-word lexical processing of Chinese two-character words

Morphologically complex words are common across different languages, especially in Chinese, because more than 90% of common modern Chinese words are complex words. Many behavioral studies have suggested the whole-word processing of Chinese complex words, but the neural correlates of whole-word processing remain unclear. Previous electrophysiological studies revealed automatic and early (∼250 ms) access to the orthographic forms of monomorphic words in the ventral occipitotemporal area. In this study, we investigated whether there is also automatic and early orthographic recognition of Chinese complex words (as whole units) by recording event-related potentials (ERPs). A total of 150 two-character words and 150 two-character pseudowords composed of the same 300 characters (morphemes) were pseudorandomly presented to proficient Chinese readers. Participants were required to determine the color of each stimulus in the color decision task and to determine whether each stimulus was a word in the lexical decision task. The two constituent characters of each stimulus were horizontally arranged in Experiment 1 and vertically arranged in Experiment 2. The results revealed a significant early ERP difference between words and pseudowords approximately 250–300 ms after stimulus onset in the parieto-occipital scalp region. The early ERP difference was more prominent in the color decision task than in the lexical decision task, more prominent in Experiment 1 than in Experiment 2, and more prominent in the left parieto-occipital scalp region than in the right. Source analysis results showed that the early ERP difference originated from the left ventral occipitotemporal cortex. These results reflected early and automatic access to whole-word orthographic representations of Chinese complex words in the left ventral occipitotemporal cortex.

Electrophysiological correlates of response time outliers: Outlier related potentials.

In response time (RT) research, RTs which largely deviate from the RT distribution are considered "outliers". Outliers are typically excluded from RT analysis building upon the implicit assumption that cognitive processing is distorted in outlier trials. The present study aims to test this assumption by comparing cognitive processing indexed by event-related potentials (ERP) of trials with outliers and valid trials in two different tasks. To this end, we compared stimulus- and response-locked ERPs for outliers identified by nine different methods with valid trials, using cluster-based permutation tests. Consistently across outlier exclusion methods and tasks, the late positive complex (P3) associated with response-related processes was reduced in outliers. Analyses of response-locked ERPs related this P3 attenuation to a slower and temporally more extended increase of the P3, possibly indexing reduced evidence accumulation speed in outliers. P3 peak amplitude in response-locked ERPs was similar between outliers and valid trials, suggesting that the absolute amount of evidence required for a response remained comparable. Furthermore, in addition to these more general ERP correlates of outliers, the contingent negative variation (CNV) ERP component was reduced in outliers as a function of preparatory demands of the task. Hence, electrophysiological correlates, and thus cognitive processing, are altered in outliers compared to valid trials. In order to avoid distortion of observed ERP differences between conditions, the RT outlier distribution should be considered for the analysis of ERPs in combined ERP and RT studies.

Perinatal nicotine exposure relates to stimulus-locked event-related potentials in early adolescence during an emotional go/no-go task

Nicotine exposure is associated with negative consequences on the developing brain, both in utero and after birth. We investigated the relationship between perinatal nicotine exposure and electroencephalographic brain activity recorded during an emotional faces Go/No-Go task among adolescents. Seventy-one adolescents aged 12–15 years completed a Go/No-Go task using fearful and happy faces. Parents completed questionnaire measures of their child's temperament and self-regulation and retrospectively reported on nicotine exposure during the perinatal period. Perinatally exposed children (n = 20) showed increased and prolonged frontal event-related potential (ERP) differentiation in stimulus-locked analyses; that is, greater emotion and condition differentiation in comparison with their non-exposed peers (n = 51). However, non-exposed children showed greater late emotion differentiation recorded over posterior sites. Response-locked ERP differences were not found. ERP effects were not related to temperamental, self-regulatory, or parental education and income-related factors. This study is the first to demonstrate a relationship between perinatal nicotine exposure and ERPs in an emotional Go/No-Go task among adolescents. Findings suggest that while conflict detection remains intact for adolescents with perinatal nicotine exposure, their attentional allocation to behaviourally relevant stimuli may be magnified to beyond optimal levels, particularly when emotion is salient in information processing. Future studies can extend these findings by isolating prenatal nicotine exposure and comparing its effects to isolated postnatal exposure and clarifying the implications of the face and performance processing differences in adolescence.

A Study on EEG Signal Features Reflecting Shapes and Colors of Simple Visual Images and their Discrimination

In this study, as a basic investigation for EEG-based visual image reconstruction, we investigated whether EEG signal features reflect shapes and colors of simple visual images which subjects viewed and whether the features can be discriminated. First, we investigated how the shapes and the colors are reflected in event-related potentials (ERP), the event-related spectrum perturbations (ERSP), and the inter-trial phase synchronization (ITC). The results showed statistically significant differences in ERP among the colors and ERP, ERSP and ITC among the shapes depending on time periods, frequency bands and electrodes. Second, based on the results, we explored learnable input data sets. Then, learnability for discriminating the shapes were shown in EEG waveforms on 100ms time periods in single trials at all channels and phase of time frequency analysis on the limited time-frequency domain and electrodes. Finally, we investigated whether two discriminators using LSTM and CNN discriminate the shapes from the learnable data for each subject. Then, it was found that accuracies of discrimination of the shapes were over a chance level with all the learnable data sets, subjects, and discriminators. We concluded that the distinct shapes can be discriminated from EEG signals by exploring appropriate features of input signals for discriminators.

Quantity Processing in Object Counting Task Based on Event-Related Potentials

In the preliminary event-dependent potentials study, our team found that the neural mechanism of Chinese singular and plural picture naming is different, and explained that the differences might lie in the different numbers of quantitative processing. However, previous studies have lacked separate neural processing of objects in singular-plural pictures. This study intends to explore the neural differences in quantity processing in singular and plural pictures by using an object counting task and combining Event-related potential (ERP). It is expected to prove that the neural differences of naming Chinese single and plural pictures found in our previous ERP research are neural processing differences of different quantities, further demonstrating that the quantity processing in Chinese singular and plural picture naming is automatic. The experimental results showed no significant differences in object counting accuracy (P=0.139) and reaction time (P=0.231) between the singular and plural groups. However, there was a noticeable difference in ERPs between the two groups (P<0.05) and statistical analysis showed that the P1 effect of the parieto-occipital lobe was greater in plural pictures than in singular pictures (140-180ms) and the P2 effect of the parieto-occipital lobe was more significant in singular pictures than in plural pictures (200-320ms). There are differences in the quantity processing of healthy adults in object counting tasks. These differences are similar to the neural differences in Chinese singular-plural picture naming, indicating that the quantity is automatically processed in this process.

Intention affects fairness processing: Evidence from behavior and representational similarity analysis of event-related potential signals.

In an ultimatum game, the responder must decide between pursuing self-interest and insisting on fairness, and these choices are affected by the intentions of the proposer. However, the time course of this social decision-making process is unclear. Representational similarity analysis (RSA) is a useful technique for linking brain activity with rich behavioral data sets. In this study, electroencephalography (EEG) was used to measure the time course of neural responses to proposed allocation schemes with different intentions. Twenty-eight participants played an ultimatum game as responders. They had to choose between accepting and rejecting the fair or unfair money allocation schemes of proposers. The schemes were offered based on the proposer's selfish intention (monetary gain), altruistic intention (donation to charity), or ambiguous intention (unknown to the responder). We used a spatiotemporal RSA and inter-subject RSA (IS-RSA) to explore the connections between event-related potentials (ERPs) after offer presentation and intention presentation with four types of behavioral data (acceptance, response time, fairness ratings, and pleasantness ratings). The spatiotemporal RSA results revealed that only response time variation was linked with the difference in ERPs at 432-592 ms after offer presentation on the posterior parietal and prefrontal regions. Meanwhile, the IS-RSA results found a significant association between inter-individual differences in response time and differences in ERP activity at 596-812 ms after the presentation of ambiguous intention, particularly in the prefrontal region. This study expands the intention-based reciprocal model to the third-party context and demonstrates that brain activity can represent response time differences in social decision-making.