The Study of Face Processing in Social Anxiety Disorder Based on Face-Specific N170 Component

Although previous studies showed that social anxiety disorder (SAD) exhibits the attentional bias for angry faces, few studies investigated effective face recognition combined with event-related potential (ERP) technique in SAD patients, especially the treatment effect. This study examines the differences in face processing in SAD patients before and after treatment and healthy control people (H-group). High-density EEG scans were registered in response to emotional schematic faces, particularly interested in the face processing N170 component. Analysis of N170 amplitude revealed a larger N170 for P-group-pre in response to inverted and upright stimuli than H-group in the right hemisphere. The result of the intragroup t-test showed that N170 was delayed for inverted relative to upright faces only in P-group-post and H-group but not in P-group-pre. Remarkably, the results of ANOVAs manifested that emotional expression cannot modulate N170 for SAD patients. Besides, the N170-based asymmetry index (AI) was introduced to analyze the left- and right-hemisphere dominance of N170 for three groups. It was found that, with the improvement of patients’ treatment, the value of A I N 170 − b a s e d presented a decreasing trend. These results together suggested that there was no inversion effect observed for patients with SAD. The change in the value of A I N 170 − b a s e d can be used as potential electrophysiological markers for the diagnosis and treatment effects on patients with SAD.

Red backgrounds have different effects on electrophysiological responses to fearful faces in groups with low and high autistic tendency

Visual processing differences in the magnocellular pathway have been reported across the autistic spectrum. On the basis that the firing of primate Type IV magnocellular cells is suppressed by diffuse red backgrounds, several groups have used red backgrounds as a means to investigate magnocellular contributions to visual processing in humans. Here, we measured emotional identification accuracy, and compared the P100 and N170 responses from groups with low (n=21; AQ<11) and high (n=22; AQ>22) Autism Spectrum Quotient (AQ) scores, in response to low (LSF) and high (HSF) spatially filtered fearful and neutral face stimuli presented on red and green backgrounds. For the LSF stimuli, the low AQ group correctly identified fearful expressions more often when presented on a red compared to a green background. The low AQ group also showed red backgrounds reduced the effect of LSF fearful expressions on P100 amplitudes. In contrast, the high AQ group showed that background colour did not significantly alter P100 responses to LSF stimuli. Interestingly, red background reduced the effects of HSF stimuli for the high AQ group. The effects of background color on LSF and HSF facial emotion responses were not evident for the N170 component. Our findings suggest that presenting face stimuli on a red background alters both magnocellular and parvocellular contributions to the P100 waveform, and that these effects differ for groups with low and high autistic tendencies. In addition, a theoretical model for explaining the temporal differences in facial emotion processing for low and high AQ groups is proposed.

Irrelevant task suppresses the N170 of automatic attention allocation to fearful faces

Recent researches have provided evidence that stimulus-driven attentional bias for threats can be modulated by top-down goals. However, it is highlight essential to indicate whether and to what extent the top-down goals can affect the early stage of attention processing and its early neural mechanism. In this study, we collected electroencephalographic data from 28 healthy volunteers with a modified spatial cueing task. The results revealed that in the irrelevant task, there was no significant difference between the reaction time (RT) of the fearful and neutral faces. In the relevant task, we found that RT of fearful faces was faster than that of neutral faces in the valid cue condition, whereas the RT of fearful faces was slower than that of neutral faces in the invalid cue condition. The N170 component in our study showed a similar result compared with RT. Specifically, we noted that in the relevant task, fearful faces in the cue position of the target evoked a larger N170 amplitude than neutral faces, whereas this effect was suppressed in the irrelevant task. These results suggest that the irrelevant task may inhibit the early attention allocation to the fearful faces. Furthermore, the top-down goals can modulate the early attentional bias for threatening facial expressions.

Mapping the Featural and Holistic Face Processing of Bad and Good Face Recognizers

Individual abilities in face recognition (good versus bad recognizers) were explored by means of event-related potentials (ERPs). The adaptation response profile of the N170 component to whole faces, eyes and mouths was used in order to highlight the crucial role of individual abilities in identity repetition processes for unfamiliar faces. The main point of this study is to underline the importance of characterizing the performance (bad or good) of the participants and to show that behaviorally selected groups might reveal neural differences. Good recognizers showed selective right hemisphere N170 repetition effects for whole faces and not for features. On the contrary, bad recognizers showed a general repetition effect not specifically related to faces and more pronounced processing for features. These findings suggest a different contribution of holistic and featural analysis in bad and good performers. In conclusion, we propose that the N170 might be used as a tool to tease apart face encoding processes as a function of individual differences.

Electrophysiological responses to negative evaluative person-knowledge: Effects of individual differences

Faces transmit rich information about a unique personal identity. Recent studies examined how negative evaluative information affects event-related potentials (ERPs), the relevance of individual differences, such as trait anxiety, neuroticism, or agreeableness, for these effects is unclear. In this preregistered study, participants (N = 80) were presented with neutral faces, either associated with highly negative or neutral biographical information. Faces were shown under three different task conditions that varied the attentional focus on face-unrelated features, perceptual face information, or emotional information. Results showed a task-independent increase of the N170 component for faces associated with negative information, while interactions occurred for the Early Posterior Negativity (EPN) and the Late Positive Potential (LPP), showing ERP differences only when paying attention to the evaluative information. Trait anxiety and neuroticism did not influence ERP differences. Low agreeableness increased EPN differences during perceptual distraction. Thus, we observed that low agreeableness leads to early increased processing of potentially hostile faces, although participants were required to attend to a face-unrelated feature.

Adaptation of The N170-Component of the Event-Related Brain Potential to Single Letters and Words in Adults and Children

Background. Neural specialization for print develops during learning to read and can be studied with event-related brain potentials (ERPs). Neural adaptation refers to smaller neural responses when a stimulus or a class of stimuli is repeated several times. Previously, neural specialization for print processing in adults has been shown to be reflected in the word-specific N170 component of the ERP. Furthermore, adapation of the N170 elicited by words has been found to correlate with reading speed. Here, we investigated adapation of the N170-component evoked by single letters, words and faces in seven to nine- year old German-language speaking children and in a group of adult normal readers. Results. For adults, we replicated previous reports of adaptation of N170-amplitude at posterior-temporal electrodes P7 and P8 for single letters and words. For children, we only observed adaptation of N170-amplitude for single letters. No adaptation of N170-amplitude was apparent for words. However, in both, children as well as adults, N170-adaptation did not correlate with measures of reading speed. For faces, that served as a non-linguistic control condition, no adaptation of N170 amplitude was observed. Conclusions. We conclude that adaptation of the word-specific N170 component of the ERP might be linked to increasing perceptual experience with letters and words.

Face Recognition Deficits in a Patient With Alzheimer's Disease: Amnesia or Agnosia? The Importance of Electrophysiological Markers for Differential Diagnosis

Face recognition deficits are frequently reported in Alzheimer's disease (AD) and often attributed to memory impairment. However, it has been hypothesized that failure in identifying familiar people could also be due to deficits in higher-level perceptual processes, since there is evidence showing a reduced inversion effect for faces but not for cars in AD. To address the involvement of these higher processes, we investigated event-related potential (ERP) neural correlates of faces in a patient with AD showing a face recognition deficit. Eight healthy participants were tested as a control group. Participants performed different tasks following the stimulus presentation. In experiment 1, they should indicate whether the stimulus was either a face or a house or a scrambled image. In experiments 2 and 3, they should discriminate between upright and inverted faces (in experiment 2, stimuli were faces with neutral or fearful expressions, while in experiment 3, stimuli were famous or unfamiliar faces). Electrophysiological results reveal that the typical face-specific modulation of the N170 component, which is thought to reflect the structural encoding of faces, was not present in patient MCG, despite being affected by the emotional content of the face implicitly processed by MCG. Conversely, the N400 component, which is thought to reflect the recruitment of the memory trace of the face identity, was found to be implicitly modulated in MCG. These results may identify a possible role for gnosic processes in face recognition deficits in AD and suggest the importance of adopting an integrated approach to the AD diagnosis while considering electrophysiological markers.

Face Perception and Narcissism: Variations of Event-Related Potential Components (P1 & N170) with Admiration and Rivalry

Previous studies have demonstrated that highly narcissistic individuals perceive themselves as grandiose and devaluate and sometimes overvalue others. These results are mainly based on behavioural data, but we still know little about the neural correlates underlying, such as perceptional processes. To this end, we investigated event-related potential components (ERP) of visual face processing (P1 and N170) and their variations with narcissism. Participants (N = 59) completed the Narcissistic Admiration and Rivalry Questionnaire and were shown pictures of their own face, a celebrity’s face, and a stranger’s face. Variations of P1 and N170 with Admiration and Rivalry were analysed using multilevel models. Results revealed moderating effects of both narcissism dimensions on the ERP components of interest. Participants with either high Admiration or low Rivalry scores showed a lower P1 amplitude when viewing their own face compared with when viewing a celebrity’s face. Moreover, the Self-Stranger difference in the N170 component (higher N170 amplitude in the Self condition) was larger for higher Rivalry scores. The findings showed, for the first time, variations of both narcissism dimensions with ERPs of early face processing. We related these effects to processes of attentional selection, an expectancy-driven perception, and the mobilisation of defensive systems. The results demonstrated that by linking self-report instruments to P1 and N170, and possibly to other ERP components, we might better understand self- and other-perception in narcissism.

Lack of awareness despite complex visual processing: Evidence from event-related potentials in a case of selective metamorphopsia

Visual awareness is thought to result from integration of low- and high-level processing; instances of integration failure provide a crucial window into the cognitive and neural bases of awareness. We present neurophysiological evidence of complex cognitive processing in the absence of awareness, raising questions about the conditions necessary for visual awareness. We describe an individual with a neurodegenerative disease who exhibits impaired visual awareness for the digits 2 to 9, and stimuli presented in close proximity to these digits, due to perceptual distortion. We identified robust event-related potential responses indicating 1) face detection with the N170 component and 2) task-dependent target-word detection with the P3b component, despite no awareness of the presence of faces or target words. These data force us to reconsider the relationship between neural processing and visual awareness; even stimuli processed by a workspace-like cognitive system can remain inaccessible to awareness. We discuss how this finding challenges and constrains theories of visual awareness.