EEG correlates (event-related desynchronization) of emotional face elaboration: a temporal analysis

An EEG frequency band analysis was conducted, in order to explore the significance of brain oscillations (delta, theta, alpha and beta) for emotional face comprehension during different post-stimulus time intervals (50-150; 150-250; 250-350; and 350-450 ms). The study was conducted on twenty adults who looked at emotional (happy, sad, angry, fearful) or neutral faces. The results showed that motivational significance of the stimulus can modulate the power synchronization (event-related desynchronization (ERD) decrease) within the frequency band of delta and theta. We propose that delta and theta respond to variations in processing stage of emotional face: whereas, delta reflects updating of the stimulus, theta responds to the emotional significance of face. The findings revealed that emotional discrimination by theta is observable mainly within 150-250 time interval and that it is more distributed on anterior regions, whereas delta is maximally synchronized within 250-350 interval and more posteriorly distributed for all the stimulus type. Finally, a right-hemisphere dominance was found for theta during emotional face comprehension.     

The impact of the stimulus features and task instructions on facial processing in social anxiety: An ERP investigation

Social anxiety has been characterized by an attentional bias towards threatening faces. Electrophysiological studies have demonstrated modulations of cognitive processing from 100 ms after stimulus presentation. However, the impact of the stimulus features and task instructions on facial processing remains unclear. Event-related potentials were recorded while high and low socially anxious individuals performed an adapted Stroop paradigm that included a colour-naming task with non-emotional stimuli, an emotion-naming task (the explicit task) and a colour-naming task (the implicit task) on happy, angry and neutral faces. Whereas the impact of task factors was examined by contrasting an explicit and an implicit emotional task, the effects of perceptual changes on facial processing were explored by including upright and inverted faces. The findings showed an enhanced P1 in social anxiety during the three tasks, without a moderating effect of the type of task or stimulus. These results suggest a global modulation of attentional processing in performance situations.     

Consciousness and arousal effects on emotional face processing as revealed by brain oscillations. A gamma band analysis.

It remains an open question whether it is possible to assign a single brain operation or psychological function for facial emotion decoding to a certain type of oscillatory activity. Gamma band activity (GBA) offers an adequate tool for studying cortical activation patterns during emotional face information processing. In the present study brain oscillations were analyzed in response to facial expression of emotions. Specifically, GBA modulation was measured when twenty subjects looked at emotional (angry, fearful, happy, and sad faces) or neutral faces in two different conditions: supraliminal (10 ms) vs subliminal (150 ms) stimulation (100 target-mask pairs for each condition). The results showed that both consciousness and significance of the stimulus in terms of arousal can modulate the power synchronization (ERD decrease) during 150-350 time range: an early oscillatory event showed its peak at about 200 ms post-stimulus. GBA was enhanced by supraliminal more than subliminal elaboration, as well as more by high arousal (anger and fear) than low arousal (happiness and sadness) emotions. Finally a left-posterior dominance for conscious elaboration was found, whereas right hemisphere was discriminant in emotional processing of face in comparison with neutral face.     

Differential modulations of reward expectation on implicit facial emotion processing: ERP evidence

Implicit emotional processing refers to the preferential processing of emotional content even if it is task irrelevant. Given that motivation enhances executive control by biasing attentional resources toward target stimuli, here we investigated the effects of reward expectation on implicit facial emotional processing in two experiments using ERPs. A precue signaling additional monetary reward for fast and accurate response for the upcoming trial (incentive condition; relative to a cue indicating no such additional reward, i.e., nonincentive condition) was followed by the presentation of a happy, angry, or neutral face. Participants had to determine the gender of the face in Experiment 1 and decide whether a number superimposed on the face was even or odd in Experiment 2. In both experiments, incentive cues elicited larger P3 and contingent negative variation responses, and the targets following incentive cues elicited more positive‐going ERPs (200–700 ms), compared with the nonincentive condition. Importantly, the N2 responses (200–280 ms) to the target exhibited differential patterns of Reward × Emotion interaction: relative to the nonincentive condition, the N2 amplitude differences between emotional (i.e., happy and/or angry) and neutral faces increased in the incentive condition in Experiment 1, but diminished in Experiment 2. These results indicate that reward expectation can differentially modulate implicit processing of facial expressions, with increased sensitivity to emotions when the processing of whole faces is required, but with reduced sensitivity when the processing of faces is distractive. This study enriches the evidence for interactions between reward‐related executive control and implicit emotional processing.     

海洛因戒断者情绪识别时面孔和声音刺激的整合

目的:考察海洛因戒断者视听情绪一致和不一致条件下的情绪识别表现,研究其情绪面孔和声音刺激的整合加工特点。方法:选取男性海洛因戒断者32例(戒断组)和健康男性30例(对照组),采用视听情绪分类任务,要求被试忽略情绪声音而对情绪面孔的类型(愤怒、快乐)做出判断。结果:戒断组在一致条件下的反应时低于不一致[(670±66)ms vs.(687±77)ms,P<0.001];戒断组不一致条件与一致条件的反应时差值低于对照组[(32±31)ms vs.(17±21)ms,P<0.05];在愤怒声音下,对照组对愤怒面孔的反应时低于快乐面孔[(653±94)ms vs.(679±78)ms,P<0.05],而戒断组对两种面孔的反应时差异无统计学意义(P>0.05)。结论:海洛因戒断者表现出了情绪多通道整合促进效应,但其多通道整合加工能力弱于正常人;戒断者多通道整合受损可能体现在对愤怒声音不敏感。     

Attentional selectivity for emotional faces: Evidence from human electrophysiology

This study investigated the temporal course of attentional biases for threat-related (angry) and positive (happy) facial expressions. Electrophysiological (event-related potential) and behavioral (reaction time [RT]) data were recorded while participants viewed pairs of faces (e.g., angry face paired with neutral face) shown for 500 ms and followed by a probe. Behavioral results indicated that RTs were faster to probes replacing emotional versus neutral faces, consistent with an attentional bias for emotional information. Electrophysiological results revealed that attentional orienting to threatening faces emerged earlier (early N2pc time window; 180–250 ms) than orienting to positive faces (after 250 ms), and that attention was sustained toward emotional faces during the 250–500-ms time window (late N2pc and SPCN components). These findings are consistent with models of attention and emotion that posit rapid attentional prioritization of threat.     

The time line of threat processing and vagal withdrawal in response to a self‐threatening stressor in cognitive avoidant copers: Evidence for vigilance‐avoidance theory

Using a spatial cueing paradigm with emotional and neutral facial expressions as cues, we examined early and late patterns of information processing in cognitive avoidant coping (CAV). Participants were required to detect a target that appeared either in the same location as the cue (valid) or in a different location (invalid). Cue–target onset asynchrony (CTOA) was manipulated to be short (250 ms) or long (750 ms). CAV was associated with early facilitation and faster disengagement from angry faces. No effects were found for happy or neutral faces. After completing the spatial cueing task, participants prepared and delivered a public speech and heart rate variability (HRV) was recorded. Disengagement from angry faces was related to a decrease in HRV in response to this task. Together, these data suggest that CAV is related to early engagement followed by disengagement from threat‐related cues that might impact physiological stress responses.     

Modification of N170 by different emotional expression of schematic faces

The N170 is widely regarded as a face sensitive potential, having its maximum at occipito-temporal sites, with right-hemisphere dominance. However, it is debatable whether the N170 is modulated by different emotional expressions of a face. The aim of this study was to analyze the N170 elicited by schematic happy and angry faces when the emotional expression is semantically processed. To investigate the influence of different emotional expressions of schematic faces, we used a Prime-Probe procedure with the N400 effect as an indicator for a semantic processing. Eighteen subjects were presented the German word "happiness" or "anger" followed by happy and angry faces. The word-face pair could be congruent or incongruent in emotional meaning. Subjects were instructed to compare the emotional meaning of the words and faces and to count the congruent trials. Event-related potentials were recorded from 124 sites. Congruent faces elicited a smaller negativity in the N400 time range than incongruent faces, indicating that the facial emotional expression was cognitively processed. The face sensitive N170 was most pronounced at posterior and occipital sites, and N170 amplitudes were larger following the angry as compared to the happy faces. It is concluded that different emotional expressions of schematic faces can modulate the N170.     

Emotional face expressions are differentiated with brain oscillations.

The differentiation of "facial expressions" is a process of higher mental activity, which has considerable applications in "psychology of moods and emotions". We applied the approach of event-related oscillations (EROs) to investigate the modulation of electrical manifestations related to emotional expression in EEG recordings of 20 healthy subjects. EROs of "neutral, angry and happy" faces in 13 electrical recordings sites (F(3), F(4), C(z), C(3), C(4), T(3), T(4), T(5), T(6), P(3), P(4), O(1), O(2)) were analyzed. Following the recording session, the subjects were asked to express the degree of their emotional involvement (valence and arousal) using the Self-Assessment Manikin ratings. Amplitude frequency characteristics (AFCs) were used to determine the frequencies of interest and the ranges for digital pass-band filtering applied accordingly. Consecutively, peak to peak amplitude measures of oscillatory responses were computed for the selected frequency bands and for the differentiation of the different stimuli. A differentiation between angry and happy facial expressions was observed especially in the alpha (9-13 Hz) and beta (15-24 Hz) frequencies, however, only when selecting stimuli with high mood involvement. Therefore, these frequency bands are the main focus of this report. The amplitudes of the alpha responses upon angry face stimulation were significantly higher than upon presentation of the happy faces at posterior locations. At F(3), C(z) and C(3), beta responses upon angry face stimulation were significantly higher in amplitude compared with the happy face stimulation. It is discussed that the frontal theta response is highly increased in comparison to all theta responses also encountered in studies of face recognition: During observation of facial expression, the occipital theta is much higher. We conclude and emphasize that the analysis of brain oscillatory responses distributed over the scalp in combination with subjective ratings of emotional impact of stimuli provide a good basis for analysing the influence of emotional information processing in the brain. In congruence with others, the results support the phylogenetical viewpoint suggesting that angry face stimulations are faster and more ample in responding. Furthermore, frontal, temporal, parietal and occipital lobes seem to be involved in processing of facial expressions, as reflected in an ensemble of different frequency brain oscillatory responses distributed over the scalp.     

Examining Socioaffective Processing Biases in Cigarette Smokers with High Versus Low Trait Hostility

Developing measures of socioaffective processing is important for understanding the mechanisms underlying emotional-interpersonal traits relevant to health, such as hostility. In this study, cigarette smokers with low (LH; n = 49) and high (HH; n = 43) trait hostility completed the Emotional Interference Gender Identification Task (EIGIT), a newly developed behavioral measure of socioaffective processing biases toward facial affect. The EIGIT involves quickly categorizing the gender of facial pictures that vary in affective valence (angry, happy, neutral, sad). Results showed that participants were slower and less accurate in categorizing the gender of angry faces in comparison to happy, neutral, and sad faces (which did not differ), signifying interference indicative of a socioaffective processing bias toward angry faces. Compared to LH individuals, HH participants exhibited diminished biases toward angry faces on error-based (but not speed-based) measures of emotional interference, suggesting impaired socioaffective processing. The EIGIT may be useful for future research on the role of socioaffective processing in traits linked with poor health.     

Emotion in motion: Facial dynamics affect infants' neural processing of emotions

Research investigating the early development of emotional processing has focused mainly on infants' perception of static facial emotional expressions, likely restricting the amount and type of information available to infants. In particular, the question of whether dynamic information in emotional facial expressions modulates infants' neural responses has been rarely investigated. The present study aimed to fill this gap by recording 7-month-olds' event-related potentials to static (Study 1) and dynamic (Study 2) happy, angry, and neutral faces. In Study 1, happy faces evoked a faster right-lateralized negative central (Nc) component compared to angry faces. In Study 2, both happy and angry faces elicited a larger right-lateralized Nc compared to neutral faces. Irrespective of stimulus dynamicity, a larger P400 to angry faces was associated with higher scores on the Negative Affect temperamental dimension. Overall, results suggest that 7-month-olds are sensitive to facial dynamics, which might play a role in shaping the neural processing of facial emotional expressions. Results also suggest that the amount of attentional resources infants allocate to angry expressions is associated to their temperamental traits. These findings represent a promising avenue for future studies exploring the neurobiological processes involved in perceiving emotional expressions using dynamic stimuli.     

Cortisol-induced enhancement of emotional face processing in social phobia depends on symptom severity and motivational context

We investigated the effects of cortisol administration on approach and avoidance tendencies in 20 patients with social anxiety disorder (SAD). Event-related brain potentials (ERPs) were measured during a reaction time task, in which patients evaluated the emotional expression of photographs of happy and angry faces by making an approaching (flexion) or avoiding (extension) arm movement. Patients showed significant avoidance tendencies for angry but not for happy faces, both in the placebo and cortisol condition. Moreover, ERP analyses showed a significant interaction of condition by severity of social anxiety on early positive (P150) amplitudes during avoidance compared to approach, indicating that cortisol increases early processing of social stimuli (in particular angry faces) during avoidance. This result replicates previous findings from a non-clinical sample of high anxious individuals and demonstrates their relevance for clinical SAD. Apparently the cortisol-induced increase in processing of angry faces in SAD depends on symptom severity and motivational context.     

The effects of cortisol administration on approach–avoidance behavior: An event-related potential study

We investigated the effects of cortisol administration (50 mg) on approach and avoidance tendencies in low and high trait avoidant healthy young men. Event-related brain potentials (ERPs) were measured during a reaction time task, in which participants evaluated the emotional expression of photographs of happy and angry faces by making an approaching (flexion) or avoiding (extension) arm movement. The task consisted of an affect-congruent (approach happy faces and avoid angry faces) and an affect-incongruent (reversed instruction) condition. Behavioral and ERP analyses showed that cortisol enhanced congruency effects for angry faces in highly avoidant individuals only. The ERP effects involved an increase of both early (P150) and late (P3) positive amplitudes, indicative of increased processing of the angry faces in high avoidant subjects after cortisol administration. Together, these results suggest a context-specific effect of cortisol on processing of, and adaptive responses to, motivationally significant threat stimuli, particularly in participants highly sensitive to threat signals.     

The acute effects of intranasal oxytocin on automatic and effortful attentional shifting to emotional faces

Oxytocin is known to promote social affiliation. The mechanism by which this occurs is unknown, but it may involve changes in social information processing. In a placebo‐controlled study, we examined the influence of intranasal oxytocin on effortful and automatic attentional shifting in 57 participants using a spatial cueing task with emotional and neutral faces. For effortful processing, oxytocin decreased the speed of shifting attention to sad faces presented for 750 ms and facilitated disengagement from right hemifield sad and angry faces presented for 200 ms. For automatic processing, symptoms of depression moderated the relationship between drug and disengagement. Oxytocin attenuated an attentional bias to masked angry faces on disengagement trials in persons with high depression scores. Oxytocin's influence on social behavior may occur, in part, by eliciting flexible attentional shifting in the early stages of information processing.     

The effects of pictures of emotional faces on tonic and phasic autonomic cardiac control in women and men

The aim of the present study was to examine autonomic function in response to negatively and positively valenced pictures under different levels of conscious recognition. Heart period variability (HPV) and heart rate (HR) reactivity were studied in 53 males and females who were being shown pictures of angry and happy faces. The pictures, which were backwardly masked, were presented once every 30 s during a 5-min period and under three conditions (counterbalanced for type of facial expression): below the level of conscious recognition (17 ms), at an intermediate level (56 ms), and at a clearly recognizable level (2370 ms). Analyses of HR power spectrum (for 5 min in each condition) in the high frequency region (HF: 0.15-0.5 Hz) that reflects respiratory sinus arrhythmia, as well as analysis of phasic heart rate responses (7.5 s in 0.5 epochs following every picture presentation) were carried out. The main findings were that HF-power was higher, and cardiac midinterval acceleration lower, in response to angry as opposed to happy faces, a result obtained only for the men, however. No interaction effect between facial expression and the three exposure conditions was found, suggesting that the pictures induced emotional activation both subliminally and supraliminally. The results were discussed in terms of increased attention to aversive stimuli.     

Adult attachment and emotional processing biases: An Event-Related Potentials (ERPs) study

Attachment-related electrophysiological differences in emotional processing biases were examined using Event-Related Potentials (ERPs). We identified ERP correlates of emotional processing by comparing ERPs elicited in trials with angry and neutral faces. These emotional expression effects were then compared across groups with secure, anxious and avoidant attachment orientations. Results revealed significant interactions between attachment orientation and facial expression in mean amplitudes of the early C1 (50-80ms post-stimulus) and P1 (80-120ms post-stimulus) ERP components. Significant differences in C1 and P1 mean amplitudes were found at occipital and posterior-parietal channels in response to angry compared with neutral faces only within the avoidant attachment group. No such differences were found within the secure or anxious attachment groups. The present study underscores the usefulness of the ERP methodology, as a sensitive measure for the study of emotional processing biases in the research field of attachment.     

The effects of cortisol administration on approach-avoidance behavior: an event-related potential study

We investigated the effects of cortisol administration (50 mg) on approach and avoidance tendencies in low and high trait avoidant healthy young men. Event-related brain potentials (ERPs) were measured during a reaction time task, in which participants evaluated the emotional expression of photographs of happy and angry faces by making an approaching (flexion) or avoiding (extension) arm movement. The task consisted of an affect-congruent (approach happy faces and avoid angry faces) and an affect-incongruent (reversed instruction) condition. Behavioral and ERP analyses showed that cortisol enhanced congruency effects for angry faces in highly avoidant individuals only. The ERP effects involved an increase of both early (P150) and late (P3) positive amplitudes, indicative of increased processing of the angry faces in high avoidant subjects after cortisol administration. Together, these results suggest a context-specific effect of cortisol on processing of, and adaptive responses to, motivationally significant threat stimuli, particularly in participants highly sensitive to threat signals.     

Identity and expression processing during classical conditioning with faces

In classical conditioning, conditioned responses (CRs) to aversively paired (CS+) relative to unpaired (CS‐) face images are often interpreted in terms of the specific individual displayed in the CS + face image having adopted an aversive emotional connotation. This interpretation requires conditioning to rely on an association between CS + face identity and the occurrence of the aversive event (UCS). Here, we tested this requirement assuming that if an association between CS + face identity and UCS occurrence is established, CRs to originally conditioned face images should transfer to novel images of same‐identity faces. Forty‐eight participants underwent MultiCS conditioning with eight neutral faces as CSs and electric shock as UCS. Central, peripheral, evaluative, and behavioral CRs signaled successful emotional learning (as reported in Pastor et al., 2015). Behavioral and EEG responses of consecutive passive viewing showed enhanced reactions to novel angry and happy expressions of previously shocked CS + versus nonshocked CS‐ identities, indicating successful CR transfer within the dimension of face identity. Investigating the nature of CR transfer, EEG revealed an interaction of identity and expression information during face processing that followed emotional congruency (i.e., stronger reactions to congruent angry CS + and happy CS‐ vs. incongruent angry CS‐ and happy CS + compounds). While correlates of transfer appeared in late and midlatency time intervals, the congruency interaction became significant within the first 100 ms of face processing. Our results suggest conditioning to rely on an association of UCS occurrence with CS + identity and point to fast dynamic interrelations between identity and expression processing.     

Facial Reactions to Facial Expressions

Previous research has demonstrated that different patterns of facial muscle activity are correlated with different emotional states. In the present study subjects were exposed to pictures of happy and angry facial expressions, in response to which their facial electromyographic (EMG) activities, heart rate (HR), and palmar skin conductance responses (SCRs) were recorded. It was found that happy and angry faces evoked different facial EMG response patterns, with increased zygomatic region activity to happy stimuli and increased corrugator region activity to angry stimuli. Furthermore, both happy and angry faces evoked HR decelerations and similar SCR magnitudes. The results are interpreted as suggesting that facial EMG recordings provide a method for distinguishing between response patterns to “positive” and “negative” emotional visual stimuli.     

Hemispheric Asymmetry in Conditioning to Facial Emotional Expressions

In the present experiment, we report a right hemisphere advantage for autonomic conditioning to facial emotional expressions. Specifically, angry, but not happy, facial expressions showed significantly more resistance to extinction when presented initially to the right as compared to the left hemisphere. Slides of happy and angry faces were used as conditioned stimuli (CS+ and CS-) with shock as the unconditioned stimulus (UCS). Half of the subjects (n = 15) had the angry face as CS+ (and the happy face as CS-), the other half had the happy face as CS+ (and the angry face as CS-). During acquisition, the CSs were presented foveally. During extinction, using the Visual Half-Field (VHF) technique, half of the CS+ and CS- trials were randomly presented in the right visual half-field (initially to the left hemisphere), and half of the trials were presented in the left half-field (initially to the right hemisphere). Stimuli were presented for 210 ms during acquisition, and for 30 ms during extinction. Bilateral skin conductance responses (SCRs) were recorded. The results showed effects of acquisition only for the angry CS+ group. During extinction, there was a significant Conditioning X Half-field interaction which was due to greater SCRs to the CS+ angry face when it was presented in the left half-field. It is concluded that the present results reveal hemisphere asymmetry effects in facial emotional conditioning.