Alexithymic features and automatic amygdala reactivity to facial emotion

Alexithymic individuals have difficulties in identifying and verbalizing their emotions. The amygdala is known to play a central role in processing emotion stimuli and in generating emotional experience. In the present study automatic amygdala reactivity to facial emotion was investigated as a function of alexithymia (as assessed by the 20-Item Toronto Alexithymia Scale). The Beck-Depression Inventory (BDI) and the State-Trait-Anxiety Inventory (STAI) were administered to measure participants' depressivity and trait anxiety. During 3T fMRI scanning, pictures of faces bearing sad, happy, and neutral expressions masked by neutral faces were presented to 21 healthy volunteers. The amygdala was selected as the region of interest (ROI) and voxel values of the ROI were extracted, summarized by mean and tested among the different conditions. A detection task was applied to assess participants' awareness of the masked emotional faces shown in the fMRI experiment. Masked sad and happy facial emotions led to greater right amygdala activation than masked neutral faces. The alexithymia feature difficulties identifying feelings was negatively correlated with the neural response of the right amygdala to masked sad faces, even when controlling for depressivity and anxiety. Reduced automatic amygdala responsivity may contribute to problems in identifying one's emotions in everyday life. Low spontaneous reactivity of the amygdala to sad faces could implicate less engagement in the encoding of negative emotional stimuli.     

Acute sleep restriction effects on emotion responses in 30- to 36-month-old children

Early childhood is a period of dramatic change in sleep and emotion processing, as well as a time when disturbance in both domains are first detected. Although sleep is recognized as central in emotion processing and psychopathology, the great majority of experimental data have been collected in adults. We examined the effects of acute sleep restriction (nap deprivation) on toddlers' emotion expression. Ten healthy children (seven females; 30-36 months old) followed a strict sleep schedule (≥12.5 h time in bed per 24-h) for 5 days, before each of two randomly assigned afternoon emotion assessments following Nap and No-Nap conditions (resulting in an 11-day protocol). Children viewed emotion-eliciting pictures (five positive, three neutral, three negative) and completed puzzles (one solvable, one unsolvable). Children's faces were video-recorded, and emotion displays were coded. When sleep restricted, children displayed less confusion in response to neutral pictures, more negativity to neutral and negative pictures, and less positivity to positive pictures. Sleep restriction also resulted in a 34% reduction in positive emotion responses (solvable puzzle), as well as a 31% increase in negative emotion responses and a 39% decrease in confused responses (unsolvable puzzle). These findings suggest sleep is a key factor in how young children respond to their world. When sleep restricted, toddlers are neither able to take full advantage of positive experiences nor are they as adaptive in challenging contexts. If insufficient sleep consistently 'taxes' young children's emotion responses, they may not manage emotion regulation challenges effectively, potentially placing them at risk for future emotional/behavioral problems.     

Using ERPs to investigate valence processing in the affect misattribution procedure

The construct validity of the affect misattribution procedure (AMP) has been challenged by theories proposing that the task does not actually measure affect misattribution. The current study tested the validity of the AMP as a measure of affect misattribution by examining three components of the ERP known to be associated with the allocation of motivated attention. Results revealed that ERP amplitudes varied in response to affectively ambiguous targets as a function of the valence of preceding primes. Furthermore, differences in ERP responses to the targets were largely similar to differences in ERPs elicited by the primes. The existence of valence differentiation in both the prime‐locked and the target‐locked ERPs, along with the similarity in this differentiation, provides evidence that the affective content of the primes is psychologically registered, and that this content influences the processing of the subsequent, evaluatively ambiguous targets, both of which are required if the priming effects found in the AMP are the result of affect misattribution. However, the behavioral priming effect was uncorrelated with ERP amplitudes, leaving some question as to the locus of this effect in the information‐processing system. Findings are discussed in light of the strengths and weaknesses of using ERPs to understand the priming effects in the AMP.     

Psychophysiological responses as indices of affective dimensions

The startle reflex, facial electromyogram (EMG), and autonomic nervous system responses were examined during imagery varying in affective valence and arousal. Subjects (N= 48) imagined affective situations during tone-cued 8-strials. Startle blink magnitudes were larger and latencies faster during negatively valent than during positively valent conditions and during high-arousal than during low-arousal conditions. Greatest heart rate acceleration and fastest and largest skin conductance responses to startle probes occurred during high-arousal imagery. Zygomatic and orbicularis oculi facial muscle activities were higher during high-arousal imagery, whereas corrugator muscle activity was higher during low-arousal imagery. Zygomatic and corrugator activity also varied with emotional valence. The startle and facial EMG responses are most parsimoniously organized by the negative affect (NA) and positive affect (PA) dimensions, respectively. This NA/PA framework integrates previous research, dimensional theories of emotional behavior, and physiological assessment of pathological emotion.     

Flashing a smile: Startle eyeblink modulation by masked affective faces

Affective faces are important stimuli with relevance to healthy and abnormal social and affective information processing. The aim of this study was to investigate the effect of brief presentations of affective faces on attention and emotional state across the time course of stimulus processing, as indexed by startle eyeblink response modulation. Healthy adults were presented with happy, neutral, and disgusted male and female faces that were backward masked by neutral faces. Startle responses were elicited at 300, 800, and 3,500 ms following stimulus presentation to probe early and late startle eyeblink modulation, indicative of attention allocation and emotional state, respectively. Results revealed that, at 300 ms, both face expression and face gender modulated startle eyeblink response, suggesting that more attention was allocated to masked happy compared to disgusted female faces, and masked disgusted compared to neutral male faces. There were no effects of either face expression or face gender on startle modulation at 800 ms. At 3,500 ms, target face expression did not modulate startle, but male faces elicited larger startle responses than female faces, indicative of a more negative emotional state. These findings provide a systematic investigation of attention and emotion modulation by brief affective faces across the time course of stimulus processing.     

Affective priming and cognitive load: Event‐related potentials suggest an interplay of implicit affect misattribution and strategic inhibition

Prior research suggests that the affective priming effect denoting prime‐congruent evaluative judgments about neutral targets preceded by affective primes increases when the primes are processed less deeply. This has been taken as evidence for greater affect misattribution. However, no study so far has combined an experimental manipulation of the depth of prime processing with the benefits of ERPs. Forty‐seven participants made like/dislike responses about Korean ideographs following 800‐ms affective prime words while 64‐channel EEG was recorded. In a randomized within‐subject design, three levels of working‐memory load were applied specifically during prime processing. Affective priming was significant for all loads and even tended to decrease over loads, although efficiency of the load manipulation was confirmed by reduced amplitudes of posterior attention‐sensitive prime ERPs. Moreover, ERPs revealed greater explicit affective discrimination of the prime words as load increased, with strongest valence effects on central/centroparietal N400 and on the parietal/parietooccipital late positive complex under high load. This suggests that (a) participants by default tried to inhibit the processing of the prime's affect, and (b) inhibition more often failed under cognitive load, thus causing emotional breakthrough that resulted in a binding of affect to the prime and, hence, reduced affect misattribution to the target. As a correlate of affective priming in the target ERP, medial‐frontal negativity, a well‐established marker of (low) stimulus value, increased with increasing negative affect of the prime. Findings support implicit prime‐target affect transfer as a major source of affective priming, but also point to the role of strategic top‐down processes.     

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.     

Dissociable effects of psychopathic traits on cortical and subcortical visual pathways during facial emotion processing: An ERP study on the N170

This study examined the relation between psychopathic traits and the brain response to facial emotion by analyzing the N170 component of the ERP. Fifty‐four healthy participants were assessed for psychopathic traits and exposed to images of emotional and neutral faces with varying spatial frequency content. The N170 was modulated by the emotional expressions, irrespective of psychopathic traits. Fearless dominance was associated with a reduced N170, driven by the low spatial frequency components of the stimuli, and dependent on the tectopulvinar visual pathway. Conversely, coldheartedness was related to overall enhanced N170, suggesting mediation by geniculostriate processing. Results suggest that different dimensions of psychopathy are related to distinct facial emotion processing mechanisms and support the existence of both amygdala deficits and compensatory engagement of cortical structures for emotional processing in psychopathy.     

Positive emotional reactions to loved names

Studies concerning personal attachment have successfully used loved familiar faces to prompt positive affective and physiological reactions. Moreover, the processing of emotional words shows similar physiological patterns to those found with affective pictures. The objective of this study was to assess whether the passive viewing of loved names would produce a pattern of subjective and physiological reactivity similar to that produced by the passive viewing of loved faces. The results showed that, compared to neutral (unknown) and famous names, loved names produced a biphasic pattern of heart rate deceleration‐acceleration, heightened skin conductance and zygomaticus muscle activity, inhibition of corrugator muscle activity, and potentiation of the startle reflex response. This pattern of physiological responses was accompanied by subjective reports of higher positive affect and arousal for loved names than for neutral and famous ones. These findings highlight not only the similarity but also the differences between the affective processing of identity recognition by loved faces and names.     

The influence of facial expression at perceptual threshold on electrodermal activity and social comfort distance

Interpersonal distance, an essential component of social interaction, is modulated by the emotion conveyed by others and associated physiological response. However, in modern societies with overcrowded and hyperstimulating environments, we can only surreptitiously glimpse the faces of others in order to quickly make behavioral adjustments. How this impacts social interactions is not yet well understood. In the present study, we investigated this issue by testing whether facial expressions that are difficult to identify modify the physiological response (Electrodermal Activity, EDA) and subsequent judgment of interpersonal comfort distance. We recorded participants’ EDA while they provided comfort judgments to interpersonal distances with a Point-Light Walker (PLW). The PLW, with an emotionally neutral gait, moved toward and crossed participants at various distances after the latter were exposed to a negative (anger), positive (happiness) or neutral facial expression presented at the perceptual threshold. Bayesian analyses of the data revealed an increase versus decrease of interpersonal comfort distance with the PLW depending on the negative versus positive emotional valence of the facial expression. They also showed an increase in EDA when the approaching PLW violated interpersonal comfort distance after participants were exposed to an angry facial expression. These effects correlated with the subjective assessment of the arousal of facial expressions. Thus, previous exposure to barely visible facial expressions can alter the representation of social comfort space and the physiological response associated with a violation of interpersonal comfort distances, depending on the valence and arousal of the emotional social stimuli.     

Facial attractiveness modulates early and late event-related brain potentials

Facial attractiveness is of high importance for human interaction and communication, and everyday experience suggests that the mere aspect of a face elicits spontaneous appraisal of attractiveness. However, little is known about the time course of brain responses related to this process. In the present study, event-related brain potentials were recorded during attractiveness classification of facial portraits that were standardized with respect to facial expression. The faces were either preceded by another face of high or low attractiveness or by an affectively neutral object. Attractive as opposed to non-attractive target faces elicited an early posterior negativity (EPN; approximately 250 ms) and a late parietal positivity (LPC; 400-600 ms), which were not modulated by affectively congruent prime faces. Elevated LPC activity had previously been shown in response to attractive versus non-attractive faces, possibly reflecting task-related evaluative processes. An enhanced EPN had been reported for faces with emotional compared to neutral emotional expression, and related to facilitated selection of emotional information. Extending these findings, our study is the first to report an attractiveness-related ERP modulation prior to the LPC, suggesting that appraising facial attractiveness starts already at processing stages associated with stimulus selection.     

Appraisal frames of pleasant and unpleasant pictures alter emotional responses as reflected in self-report and facial electromyographic activity

Emotional pictures elicit responses across experiential, behavioral and physiological systems. The magnitude of these responses can be modulated by altering one's interpretation of emotional stimuli. Previous studies have indicated that appraisal frames affect subsequent interpretations of upcoming stimuli so as to alter self-reported emotions, ERP activity and autonomic responses. No studies to date have examined the effect of appraisal frames on expressive behaviors as measured by facial EMG. This study aims to test the hypothesis that appraisal frames can alter both emotional experience and facial expression and attempts to examine their effect on the temporal unfolding of facial expressions. Participants (N=20) were exposed to 125 pairs of appraisal frames (neutral or negative/positive) followed by neutral, unpleasant, or pleasant pictures reflecting five conditions: unpleasant-negative, unpleasant-neutral, pleasant-positive, pleasant-neutral and neutral-neutral. Results indicate that the unpleasant-negative compared to the unpleasant-neutral condition led to greater self-reported unpleasantness and arousal, as well as greater corrugator activity, and the pleasant-positive compared to the pleasant-neutral condition led to greater self-reported pleasantness and zygomaticus activity; modulation of facial responses became evident 0.5-1.0s after stimulus onset. These results suggest that appraisal frames effectively alter both emotional experience and facial expressions.     

What our eyes tell us about feelings: Tracking pupillary responses during emotion regulation processes

Emotion regulation is essential for adaptive behavior and mental health. Strategies applied to alter emotions are known to differ in their impact on psychological and physiological aspects of the emotional response. However, emotion regulation outcome has primarily been assessed via self‐report, and studies comparing regulation strategies with regard to their peripheral physiological mechanisms are limited in number. In the present study, we therefore aimed to investigate the effects of different emotion regulation strategies on pupil dilation, skin conductance responses, and subjective emotional responses. Thirty healthy females were presented with negative and neutral pictures and asked to maintain or up‐ and downregulate their upcoming emotional responses through reappraisal or distraction. Pupil dilation and skin conductance responses were significantly enhanced when viewing negative relative to neutral pictures. For the pupil, this emotional arousal effect manifested specifically late during the pupillary response. In accordance with subjective ratings, increasing negative emotions through reappraisal led to the most prominent pupil size enlargements, whereas no consistent effect for downregulation was found. In contrast, early peak dilations were enhanced in all emotion regulation conditions independent of strategy. Skin conductance responses were not further modulated by emotion regulation. These results indicate that pupil diameter is modulated by emotional arousal, but is initially related to the extent of mental effort required to regulate automatic emotional responses. Our data thus provide first evidence that the pupillary response might comprise two distinct temporal components reflecting cognitive emotion regulation effort on the one hand and emotion regulation success on the other hand.     

Emotional content modulates response inhibition and perceptual processing

In this study, event‐related potentials were used to investigate the effect of emotion on response inhibition. Participants performed an emotional go/no‐go task that required responses to human faces associated with a “go” valence (i.e., emotional, neutral) and response inhibition to human faces associated with a “no‐go” valence. Emotional content impaired response inhibition, as evidenced by decreased response accuracy and N2 amplitudes in no‐go trials. More importantly, emotional expressions elicited larger N170 amplitudes than neutral expressions, and this effect was larger in no‐go than in go trials, indicating that the perceptual processing of emotional expression had priority in inhibitory trials. In no‐go trials, correlation analysis showed that increased N170 amplitudes were associated with decreased N2 amplitudes. Taken together, our findings suggest that emotional content impairs response inhibition due to the prioritization of emotional content processing.     

Automatic emotion regulation in response inhibition: The temporal dynamics of emotion counter‐regulation during a go/no‐go task

Recent behavioral studies indicate that emotion counter‐regulation automatically allocates attention to events that are opposite in the valence to the experienced emotional state. The present study explored the effect of emotion counter‐regulation on response inhibition by using ERPs in a go/no‐go paradigm. We recruited 58 subjects and randomly assigned them to either the angry priming group (watching Nanjing Massacre movie clips) or the neutral priming group (watching “mending a computer” movie clips). The behavioral results revealed that participants in the angry priming group responded significantly more accurately to go happy and no‐go angry faces than go angry and no‐go happy faces. The analyses of ERPs revealed that the amplitudes of the no‐go N2 and no‐go P3 were significantly larger for the happy faces than for the angry faces in the angry priming group. However, no such effects were found in the neutral priming group. These results suggest that highly aroused angry emotion could prompt a priority response to happy emotion stimuli and restrict the responses to angry emotion stimuli through emotion counter‐regulation.     

Love withdrawal is related to heightened processing of faces with emotional expressions and incongruent emotional feedback: evidence from ERPs

Parental use of love withdrawal is thought to affect children's later psychological functioning because it creates a link between children's performance and relational consequences. To investigate whether love withdrawal is also associated with the underlying level of basic information processing in the brain, we studied event-related potentials to feedback stimuli that combined performance feedback with emotional facial expressions. We focused on the VPP (face processing) and N400 (incongruence processing). More maternal use of love withdrawal was related to more positive VPP amplitudes, larger effects of the emotional facial expression on VPP amplitude, and more negative N400 responses to incongruent combinations of feedback and facial expressions. Our findings suggest a heightened processing of faces with emotional expressions and greater sensitivity to incongruence between feedback and facial expression in individuals who experienced more love withdrawal.     

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.     

Automatic brain response to facial emotion as a function of implicitly and explicitly measured extraversion

Extraversion/introversion is a basic dimension of personality that describes individual differences in social behavior and sensory sensitivity. Previous neuroimaging research exclusively relied on self reports for assessing personality traits. In recent years, implicit measures of personality have been developed that aim at assessing the implicit self-concept of personality and complement self report instruments which are thought to measure aspects of the explicit self-concept of personality. In the present study functional magnetic resonance imaging was used to examine automatic brain reactivity to facial expression as a function of both implicitly and explicitly measured extraversion in 30 healthy women. Sad, happy, and neutral faces were presented for 33 ms masked by neutral faces beside a no face control condition. Subjects evaluated the briefly shown neutral mask faces. The Implicit Association Test (IAT) and the NEO Five-Factor Inventory (NEO-FFI) were applied as measures of extraversion which were not correlated in our sample. IAT extraversion was negatively correlated with automatic reactivity of the caudate head, thalamus, and inferior frontal cortex to sad faces. NEO-FFI extraversion was negatively correlated with response of the inferior frontal cortex and putamen to sad faces. For masked happy faces, an inverse correlation of the IAT effect for extraversion with activation of the caudate head and superior parietal lobule was observed. NEO-FFI extraversion was inversely correlated with the response of the thalamus to happy faces. Neither NEO-FFI extraversion nor IAT effect were significantly related to brain response to masked neutral faces (compared to the no face condition). Taken together, a specific heightened responsivity of the fronto-striatal-thalamic circuit to facial emotions which are arousing stimuli might underlie introverts' preference for avoiding social interactions. Research on the neurobiology of extraversion could benefit from the application of implicit in addition to explicit measurement instruments when automatic neural responses are investigated.     

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.     

Facial expression recognition and emotional regulation in narcolepsy with cataplexy

Cataplexy is pathognomonic of narcolepsy with cataplexy, and defined by a transient loss of muscle tone triggered by strong emotions. Recent researches suggest abnormal amygdala function in narcolepsy with cataplexy. Emotion treatment and emotional regulation strategies are complex functions involving cortical and limbic structures, like the amygdala. As the amygdala has been shown to play a role in facial emotion recognition, we tested the hypothesis that patients with narcolepsy with cataplexy would have impaired recognition of facial emotional expressions compared with patients affected with central hypersomnia without cataplexy and healthy controls. We also aimed to determine whether cataplexy modulates emotional regulation strategies. Emotional intensity, arousal and valence ratings on Ekman faces displaying happiness, surprise, fear, anger, disgust, sadness and neutral expressions of 21 drug‐free patients with narcolepsy with cataplexy were compared with 23 drug‐free sex‐, age‐ and intellectual level‐matched adult patients with hypersomnia without cataplexy and 21 healthy controls. All participants underwent polysomnography recording and multiple sleep latency tests, and completed depression, anxiety and emotional regulation questionnaires. Performance of patients with narcolepsy with cataplexy did not differ from patients with hypersomnia without cataplexy or healthy controls on both intensity rating of each emotion on its prototypical label and mean ratings for valence and arousal. Moreover, patients with narcolepsy with cataplexy did not use different emotional regulation strategies. The level of depressive and anxious symptoms in narcolepsy with cataplexy did not differ from the other groups. Our results demonstrate that narcolepsy with cataplexy accurately perceives and discriminates facial emotions, and regulates emotions normally. The absence of alteration of perceived affective valence remains a major clinical interest in narcolepsy with cataplexy, and it supports the argument for optimal behaviour and social functioning in narcolepsy with cataplexy.