N170 ERP Research Articles

An ERP Study of Face Processing in Schizophrenia, Bipolar Disorder, and Socially Isolated Individuals from the Community.

People with schizophrenia (SCZ) and bipolar disorder (BD) have impairments in processing social information, including faces. The neural correlates of face processing are widely studied with the N170 ERP component. However, it is unclear whether N170 deficits reflect neural abnormalities associated with these clinical conditions or differences in social environments. The goal of this study was to determine whether N170 deficits would still be present in SCZ and BD when compared with socially isolated community members. Participants included 66 people with SCZ, 37 with BD, and 125 community members (76 "Community-Isolated"; 49 "Community-Connected"). Electroencephalography was recorded during a face processing task in which participants identified the gender of a face, the emotion of a face (angry, happy, neutral), or the number of stories in a building. We examined group differences in the N170 face effect (greater amplitudes for faces vs buildings) and the N170 emotion effect (greater amplitudes for emotional vs neutral expressions). Groups significantly differed in levels of social isolation (Community-Isolated > SCZ > BD = Community-Connected). SCZ participants had significantly reduced N170 amplitudes to faces compared with both community groups, which did not differ from each other. The BD group was intermediate and did not differ from any group. There were no significant group differences in the processing of specific emotional facial expressions. The N170 is abnormal in SCZ even when compared to socially isolated community members. Hence, the N170 seems to reflect a social processing impairment in SCZ that is separate from level of social isolation.

Age-related similarities and differences in cognitive and neural processing revealed by task-related microstate analysis

We explored neural processing differences associated with aging across four cognitive functions. In addition to ERP analysis, we included task-related microstate analyses, which identified stable states of neural activity across the scalp over time, to explore whole-head neural activation differences. Younger and older adults (YA, OA) completed face perception (N170), word-pair judgment (N400), visual oddball (P3), and flanker (ERN) tasks. Age-related effects differed across tasks. Despite age-related delayed latencies, N170 ERP and microstate analyses indicated no age-related differences in amplitudes or microstates. However, age-related condition differences were found for P3 and N00 amplitudes and scalp topographies: smaller condition differences were found for in OAs as well as broader centroparietal scalp distributions. Age group comparisons for the ERN revealed similar focal frontocentral activation loci, but differential activation patterns. Our findings of differential age effects across tasks are most consistent with the STAC-r framework which proposes that age-related effects differ depending on the resources available and the kinds of processing and cognitive load required of various tasks.

Scrutinizing Whether Mere Group Membership Influences the N170 Response to Faces: Results from Two Preregistered Event-Related Potential Studies.

A socially consequential test of the cognitive penetrability of visual perception is whether merely sharing a group membership with another person influences how you encode their face. Past research has examined this issue by manipulating group membership with techniques from social psychology and then measuring the face-sensitive N170 ERP. However, methodological differences across studies make it difficult to draw conclusions from this literature. In our research, we conducted two large-scale, preregistered ERP studies to address how critical methodological decisions could influence conclusions about top-down effects of group membership on face perception. Specifically, we examined how mere group membership, perceptual markers that signify group membership, number of trials included in the study design, the racial/ethnic identity of face stimuli, and the data analytic approach affect inferences about the N170 response to faces. In Study 1, we found no evidence that mere group membership significantly influenced the N170. However, we found that the background color used to signify group membership modulated the magnitude and latency of the N170. Exploratory analyses also showed effects of stimulus race/ethnicity. In Study 2, we dissociated background color from face encoding by presenting background color before the faces. In this second study, we found no main effect of group membership, background color, or stimulus race/ethnicity. However, we did see an unhypothesized mere group membership effect on trials toward the end of the study. Our results inform debates about social categorization effects on visual perception and show how bottom-up indicators of group membership can bias face encoding.

Contrast reversal of the iris and sclera increases the face sensitive N170.

Previous research has demonstrated that reversing the contrast of the eye region, which includes the eyebrows, affects the N170 ERP. To selectively assess the impact of just the eyes, the present study evaluated the N170 in response to reversing contrast polarity of just the iris and sclera in upright and inverted face stimuli. Contrast reversal of the eyes increased the amplitude of the N170 for upright faces, but not for inverted faces, suggesting that the contrast of eyes is an important contributor to the N170 ERP.

Neurocognitive effects of a training program for poor face recognizers using shape and texture caricatures: A pilot investigation

Recent research suggested disproportional usage of shape information by people with poor face recognition, although texture information appears to be more important for familiar face recognition. Here, we tested a training program with faces that were selectively caricatured in either shape or texture parameters. Forty-eight young adults with poor face recognition skills (1 SD below the mean in at least 2/3 face processing tests: CFMT, GFMT, BFFT) were pseudo-randomly assigned to either one of two training groups or a control group (n = 16 each). Training comprised six sessions over three weeks. Per session, participants studied ten unfamiliar facial identities whose shape or texture characteristics were caricatured. Before and after training (or waiting in the control group), all participants completed EEG experiments on face learning and famous face recognition, and behavioral face processing tests. Results showed small but specific training-induced improvements: Whereas shape training improved face matching (training tasks, and to some extent GFMT), texture training elicited marked improvements in face learning (CFMT). Moreover, for the texture training group the N170 ERP was enhanced for novel faces post-training, suggesting training-induced changes in early markers of face processing. Although further research is necessary, this suggests that parameter-specific caricature training is a promising way to improve performance in people with poor face recognition skills.

Turning the Face Inversion Effect on Its Head: Violated Expectations of Orientation, Lighting, and Gravity Enhance N170 Amplitudes.

Face inversion effects occur for both behavioral and electrophysiological responses when people view faces. In EEG, inverted faces are often reported to evoke an enhanced amplitude and delayed latency of the N170 ERP. This response has been attributed to the indexing of specialized face processing mechanisms within the brain. However, inspection of the literature revealed that, although N170 is consistently delayed to a variety of face representations, only photographed faces invoke enhanced N170 amplitudes upon inversion. This suggests that the increased N170 amplitudes to inverted faces may have other origins than the inversion of the face's structure. We hypothesize that the unique N170 amplitude response to inverted photographed faces stems from multiple expectation violations, over and above structural inversion. For instance, rotating an image of a face upside-down not only violates the expectation that faces appear upright but also lifelong priors about illumination and gravity. We recorded EEG while participants viewed face stimuli (upright vs. inverted), where the faces were illuminated from above versus below, and where the models were photographed upright versus hanging upside-down. The N170 amplitudes were found to be modulated by a complex interaction between orientation, lighting, and gravity factors, with the amplitudes largest when faces consistently violated all three expectations. These results confirm our hypothesis that face inversion effects on N170 amplitudes are driven by a violation of the viewer's expectations across several parameters that characterize faces, rather than a disruption in the configurational disposition of its features.

Emotion processing in children who do and do not stutter: An ERP study of electrocortical reactivity and regulation to peer facial expressions

PurposeEvent-related brain potentials (ERPs) were used to investigate the neural correlates of emotion processing in 5- to 8-year-old children who do and do not stutter. MethodsParticipants were presented with an audio contextual cue followed by images of threatening (angry/fearful) and neutral facial expressions from similarly aged peers. Three conditions differed in audio-image pairing: neutral context-neutral expression (neutral condition), negative context-threatening expression (threat condition), and reappraisal context-threatening expression (reappraisal condition). These conditions reflected social stimuli that are ecologically valid to the everyday life of children. ResultsP100, N170, and late positive potential (LPP) ERP components were elicited over parietal and occipital electrodes. The threat condition elicited an increased LPP mean amplitude compared to the neutral condition across our participants, suggesting increased emotional reactivity to threatening facial expressions. In addition, LPP amplitude decreased during the reappraisal condition— evidence of emotion regulation. No group differences were observed in the mean amplitude of ERP components between children who do and do not stutter. Furthermore, dimensions of childhood temperament and stuttering severity were not strongly correlated with LPP elicitation. ConclusionThese findings are suggestive that, at this young age, children who stutter exhibit typical brain activation underlying emotional reactivity and regulation to social threat from peer facial expressions.

A validation of Emotiv EPOC Flex saline for EEG and ERP research.

BackgroundPrevious work has validated consumer-grade electroencephalography (EEG) systems for use in research. Systems in this class are cost-effective and easy to set up and can facilitate neuroscience outside of the laboratory. The aim of the current study was to determine if a new consumer-grade system, the Emotiv EPOC Saline Flex, was capable of capturing research-quality data.MethodThe Emotiv system was used simultaneously with a research-grade EEG system, Neuroscan Synamps2, to collect EEG data across 16 channels during five well-established paradigms: (1) a mismatch negativity (MMN) paradigm that involved a passive listening task in which rare deviant (1,500 Hz) tones were interspersed amongst frequent standard tones (1,000 Hz), with instructions to ignore the tones while watching a silent movie; (2) a P300 paradigm that involved an active listening task in which participants were asked to count rare deviant tones presented amongst frequent standard tones; (3) an N170 paradigm in which participants were shown images of faces and watches and asked to indicate whether the images were upright or inverted; (4) a steady-state visual evoked potential (SSVEP) paradigm in which participants passively viewed a flickering screen (15 Hz) for 2 min; and (5) a resting state paradigm in which participants sat quietly with their eyes open and then closed for 3 min each.ResultsThe MMN components and P300 peaks were equivalent between the two systems (BF10 = 0.25 and BF10 = 0.26, respectively), with high intraclass correlations (ICCs) between the ERP waveforms (>0.81). Although the N170 peak values recorded by the two systems were different (BF10 = 35.88), ICCs demonstrated that the N170 ERP waveforms were strongly correlated over the right hemisphere (P8; 0.87–0.97), and moderately-to-strongly correlated over the left hemisphere (P7; 0.52–0.84). For the SSVEP, the signal-to-noise ratio (SNR) was larger for Neuroscan than Emotiv EPOC Flex (19.94 vs. 8.98, BF10 = 51,764), but SNR z-scores indicated a significant brain response at the stimulus frequency for both Neuroscan (z = 12.47) and Flex (z = 11.22). In the resting state task, both systems measured similar alpha power (BF10 = 0.28) and higher alpha power when the eyes were closed than open (BF10 = 32.27).ConclusionsThe saline version of the Emotiv EPOC Flex captures data similar to that of a research-grade EEG system. It can be used to measure reliable auditory and visual research-quality ERPs. In addition, it can index SSVEP signatures and is sensitive to changes in alpha oscillations.

Disentangling presentation and processing times in the brain

Visual object recognition seems to occur almost instantaneously. However, not only does it require hundreds of milliseconds of processing, but our eyes also typically fixate the object for hundreds of milliseconds. Consequently, information reaching our eyes at different moments is processed in the brain together. Moreover, information received at different moments during fixation is likely to be processed differently, notably because different features might be selectively attended at different moments. Here, we introduce a novel reverse correlation paradigm that allows us to uncover with millisecond precision the processing time course of specific information received on the retina at specific moments. Using faces as stimuli, we observed that processing at several electrodes and latencies was different depending on the moment at which information was received. Some of these variations were caused by a disruption occurring 160–200 ​ms after the face onset, suggesting a role of the N170 ERP component in gating information processing; others hinted at temporal compression and integration mechanisms. Importantly, the observed differences were not explained by simple adaptation or repetition priming, they were modulated by the task, and they were correlated with differences in behavior. These results suggest that top-down routines of information sampling are applied to the continuous visual input, even within a single eye fixation.

Play to Win: Action Video Game Experience and Attention Driven Perceptual Exploration in Categorization Learning.

Categorization learning is a fundamental and complex cognitive ability. The present EEG study examined how much action video gamers differ from non-gamers in the usage of visual exploration and attention driven perceptual analyses during a categorization learning task. Seventeen healthy right-handed non-gamers and 16 healthy right-handed action video gamers performed a visual categorization task with 14 ring stimuli, which were divided into two categories. All stimuli had the same structure but differed with respect to their color combinations and were forming two categories including a prototype, five typical stimuli and one exception. The exception shared most similarities with the prototype of the opposite group. Prototypes and typical stimuli were correctly categorized at an early stage of the experiment, whereas the successful categorization of exceptions occurred later. The behavioral data yield evidence that action video gamers perform correct categorizations of exceptions earlier than non-gamers. Additionally, groups differed with respect to differential expressions of the attention related P150 ERP component (early perceptual analysis) and the N170 ERP component, which reflected differential processing demands for the stimulus material. In comparison to non-gamers, the analyses of the eye movements yield for action video gamers different, more central fixations possibly indicating covert peripheral processing. For both groups fixations as well as saccades decrease and in the case of exceptions, one of the two segments that are decisive for correct categorization shows higher fixation rates at the end of the experiment. These findings indicate for both groups a learning process regarding the stimulus material. Regarding the group differences, we interpret the results to indicate that action video gamers show a different stimulus exploration, use an enhanced early perceptual analysis of the stimulus material and therefore may detect changes in objects faster and learned the belonging of the stimuli to their categories in an earlier trial phase.

Social categorization modulates own-age bias in face recognition and ERP correlates of face processing

The aim of the present study was to further understanding of how social categorization influences face recognition. According to the categorization-individuation model, face recognition can either be biased toward categorization or individuation. We hypothesized that the face recognition bias associated with a social category (e.g., the own-age bias) would be larger when faces were initially categorized according to that category. To examine this hypothesis, young adults (N = 63) completed a face recognition task after either making age or sex judgments while encoding child and adult faces. Young adults showed the own-age and own-sex biases in face recognition. Consistent with our hypothesis, the magnitude of the own-age bias in face recognition was larger when individuals made age, rather than sex, judgments at encoding. To probe the mechanisms underlying this effect, we examined ERP responses to child and adult faces across the social categorization conditions. Neither the P1 nor the N170 ERP components were modulated by the social categorization task or the social category membership of the face. However, the P2, which is associated with second-order configural processing, was larger to adult faces than child faces only in the age categorization condition. The N250, which is associated with individuation, was larger (i.e., more negative) to adult than child faces and during age categorization than sex categorization. These results are interpreted within the context of the categorization-individuation model and current research on biases in face recognition.

Scarcity disrupts the neural encoding of Black faces: A socioperceptual pathway to discrimination.

When economic resources are scarce, racial minorities are often devalued and disenfranchised. We proposed that this pattern extends to visual processing, such that the encoding of minority group faces is disrupted under scarcity-an effect that may facilitate discrimination and contribute to racial disparities. Specifically, we used EEG and fMRI to test whether scarce economic conditions induce deficits in neural encoding of Black faces, and we examined whether this effect is associated with discriminatory resource allocation in behavior. In Study 1, framing resources as scarce (vs. neutral) selectively impaired the neural encoding of Black (vs. White) faces, as indexed by a delayed face-related N170 ERP response, and the degree of this encoding deficit predicted anti-Black allocation decisions. In Study 2, we replicated and extended this effect using fMRI: Resources framed as scarce (vs. neutral) reduced face-sensitive fusiform activity to Black (vs. White) faces. Furthermore, scarcity-decreased fusiform activity to Black faces corresponded with decreased valuation-related striatum activity to predict anti-Black allocation decisions. These findings suggest that impaired visual processing and devaluation occur selectively for minorities under scarcity-an implicit effect that may promote discrimination and contribute to rising disparities observed during economic stress. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Peripheral preview abolishes N170 face-sensitivity at fixation: Using fixation-related potentials to investigate dynamic face processing

ABSTRACTThe N170 ERP peak has been found to be consistently larger in response to the presentation of faces than to other objects, yet it is not clear whether this face-sensitive N170 is also elicited during fixations made subsequent to the initial presentation. To investigate this question, the current study utilised Event and Fixation-Related Potentials in two experiments, time-locking brain potentials to the presentation of faces and objects (watches) images in participants’ peripheral vision, and to their first fixations on the images. Experiment 1 found that a face-sensitive N170 was elicited by the onset of images but not by a subsequent fixation on the images, and that face inversion did not modulate N170 beyond presentation. Experiment 2 found that disrupting the structure of the peripheral preview (phase-scrambling) led to a face-sensitive N170 at fixation onsets on the intact-images. Interestingly, N170 amplitudes for both faces and objects were significantly enhanced after the peripheral preview was phase-scrambled, suggesting that the N170 in part reflects a category-detection process that is elicited once when an image structure is viewed. These results indicate that neural processing during fixations will be significantly modulated when they are immediately preceded by peripheral previews, and is not specific to faces.

The Relationship of Individual Differences of Face-specific N170 ERP Component with Face Perception and Facial Emotion Recognition

The Relationship of Individual Differences of Face-specific N170 ERP Component with Face Perception and Facial Emotion Recognition

Immediate and delayed auditory feedback in declarative learning: An examination of the feedback related event related potentials

The study examined the effect of feedback timing on the FRN and N170 ERP components in the context of feedback-based learning, by manipulating feedback timing and presenting auditory feedback. Previous studies reported that the FRN was modulated by feedback timing when feedback was visual. Additionally, the N170 ERP component was recently found to be sensitive to the timing of visual feedback (Arbel et al., 2017). The purpose of the present study was to elucidate the extent to which the FRN and N170 are modulated by feedback timing when feedback is auditory. Thirty healthy young adults were tasked with learning the names of 56 novel objects through trial-and-error guided by feedback in a two-choice paired association task. The 56 object-name pairs were divided into four sets, each containing fourteen items presented in five training blocks and a sixth testing block. In two of the sets auditory feedback was given 500 ms following a response, and in the two other sets feedback delivery was delayed by 6500 ms. The FRN was not found sensitive to the timing of the auditory feedback. However, sensitivity to timing was found in the N1-P2 complex preceding the FRN. The N170 was found sensitive to both feedback timing and valence, providing additional evidence to its relevance to feedback processing. Moreover, the elicitation of the N170 by auditory feedback suggests that the system that gives rise to the N170 in the context of processing delayed feedback is not unique to visual input.

The neural sources of N170: Understanding timing of activation in face-selective areas.

The N170 ERP component has been widely identified as a face-sensitive neural marker. Despite extensive investigations conducted to examine the neural sources of N170, there are two issues in prior literature: (a) few studies used individualized anatomy as head model for the cortical source analysis of the N170, and (b) the relationship between the N170 and face-selective regions from fMRI studies is unclear. Here, we addressed these questions by presenting pictures of faces and houses to the same group of healthy adults and recording structural MRI, fMRI, and high-density ERPs in separate sessions. Source analysis based on the participant's anatomy showed that the middle and posterior fusiform gyri were the primary neural sources for the face-sensitive aspects of the N170. Source analysis based on regions of interest from the fMRI revealed that the fMRI-defined fusiform face area was the major contributor to the N170. The current study suggests that the fusiform gyrus is a major neural contributor to the N170 ERP component and provides further insights about the spatiotemporal characteristics of face processing.

モバイル型簡易脳波計Emotiv EPOC+による顔に対するN170成分の計測の信頼性

モバイル型簡易脳波計Emotiv EPOC+による顔に対するN170成分の計測の信頼性

Can a Novel High-Density EEG Approach Disentangle the Differences of Visual Event Related Potential (N170), Elicited by Negative Facial Stimuli, in People with Subjective Cognitive Impairment?

Studies on subjective cognitive impairment (SCI) and neural activation report controversial results. To evaluate the ability to disentangle the differences of visual N170 ERP, generated by facial stimuli (Anger & Fear) as well as the cognitive deterioration of SCI, mild cognitive impairment (MCI), and Alzheimer's disease (AD) compared to healthy controls (HC). 57 people took part in this study. Images corresponding to facial stimuli of "Anger" and "Fear" were presented to 12 HC, 14 SCI, 17 MCI and 14 AD participants. EEG data were recorded by using a HD-EEG HydroCel with 256 channels. Results showed that the amplitude of N170 can contribute in distinguishing the SCI group, since statistically significant differences were observed with the HC (p < 0.05) and the MCI group from HC (p < 0.001), as well as AD from HC (p = 0.05) during the processing of facial stimuli. Noticeable differences were also observed in the topographic distribution of the N170 amplitude, while localization analysis by using sLORETA images confirmed the activation of superior, middle-temporal, and frontal lobe brain regions. Finally, in the case of "Fear", SCI and HC demonstrated increased activation in the orbital and inferior frontal gyrus, respectively, MCI in the inferior temporal gyrus, and AD in the lingual gyrus. These preliminary findings suggest that the amplitude of N170 elicited after negative facial stimuli could be modulated by the decline related to pathological cognitive aging and can contribute in distinguishing HC from SCI, MCI, and AD.

Increased Early Sensitivity to Eyes in Mouthless Faces: In Support of the LIFTED Model of Early Face Processing.

The N170 ERP component is a central neural marker of early face perception usually thought to reflect holistic processing. However, it is also highly sensitive to eyes presented in isolation and to fixation on the eyes within a full face. The lateral inhibition face template and eye detector (LIFTED) model (Nemrodov et al. in NeuroImage 97:81-94, 2014) integrates these views by proposing a neural inhibition mechanism that perceptually glues features into a whole, in parallel to the activity of an eye detector that accounts for the eye sensitivity. The LIFTED model was derived from a large number of results obtained with intact and eyeless faces presented upright and inverted. The present study provided a control condition to the original design by replacing eyeless with mouthless faces, hereby enabling testing of specific predictions derived from the model. Using the same gaze-contingent approach, we replicated the N170 eye sensitivity regardless of face orientation. Furthermore, when eyes were fixated in upright faces, the N170 was larger for mouthless compared to intact faces, while inverted mouthless faces elicited smaller amplitude than intact inverted faces when fixation was on the mouth and nose. The results are largely in line with the LIFTED model, in particular with the idea of an inhibition mechanism involved in holistic processing of upright faces and the lack of such inhibition in processing inverted faces. Some modifications to the original model are also proposed based on these results.

Is it about me? Time-course of self-relevance and valence effects on the perception of neutral faces with direct and averted gaze

Most face processing research has investigated how we perceive faces presented by themselves, but we view faces everyday within a rich social context. Recent ERP research has demonstrated that context cues, including self-relevance and valence, impact electrocortical and emotional responses to neutral faces. However, the time-course of these effects is still unclear, and it is unknown whether these effects interact with the face gaze direction, a cue that inherently contains self-referential information and triggers emotional responses. We primed direct and averted gaze neutral faces (gaze manipulation) with contextual sentences that contained positive or negative opinions (valence manipulation) about the participants or someone else (self-relevance manipulation). In each trial, participants rated how positive or negative, and how affectively aroused, the face made them feel. Eye-tracking ensured sentence reading and face fixation while ERPs were recorded to face presentations. Faces put into self-relevant contexts were more arousing than those in other-relevant contexts, and elicited ERP differences from 150 to 750 ms post-face, encompassing EPN and LPP components. Self-relevance interacted with valence at both the behavioural and ERP level starting 150 ms post-face. Finally, faces put into positive, self-referential contexts elicited different N170 ERP amplitudes depending on gaze direction. Behaviourally, direct gaze elicited more positive valence ratings than averted gaze during positive, self-referential contexts. Thus, self-relevance and valence contextual cues impact visual perception of neutral faces and interact with gaze direction during the earliest stages of face processing. The results highlight the importance of studying face processing within contexts mimicking the complexities of real world interactions.