Masked affective stimuli moderate task difficulty effects on effort-related cardiovascular response

This experiment investigated the combined effect of masked affective stimuli and task difficulty on effort-related cardiovascular response. Cardiovascular reactivity (ICG, blood pressure) was recorded during a baseline period and performance of an easy or difficult attention task in which participants were exposed to masked sad vs. happy facial expressions. As expected, participants in the sad-faces/easy and happy-faces/difficult conditions showed stronger sympathetic nervous system discharge to the heart and vasculature--shorter preejection period, higher systolic blood pressure--indicating more effort than participants in the sad-faces/difficult and happy-faces/easy conditions. Total peripheral resistance reacted similarly as preejection period and systolic blood pressure. The findings are compatible with the effects of consciously experienced affect on effort-related cardiovascular response.     

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.     

N170 response to facial expressions is modulated by the affective congruency between the emotional expression and preceding affective picture

Does contextual affective information influence the processing of facial expressions already at the relatively early stages of face processing? We measured event-related brain potentials to happy and sad facial expressions primed by preceding pictures with affectively positive and negative scenes. The face-sensitive N170 response amplitudes showed a clear affective priming effect: N170 amplitudes to happy faces were larger when presented after positive vs. negative primes, whereas the N170 amplitudes to sad faces were larger when presented after negative vs. positive primes. Priming effects were also observed on later brain responses. The results support an early integration in processing of contextual and facial affective information. The results also provide neurophysiological support for theories suggesting that behavioral affective priming effects are based, at least in part, on facilitation of encoding of incoming affective information.     

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.     

Temporal pole activity during perception of sad faces,but not happy faces,correlates with neuroticism trait

It is known that the temporal cortex is involved in perception of emotional facial expressions, and the involvement is relatively independent of the emotional valence of those expressions. The present study revealed a valence-dependent aspect of the temporal cortex through individual differences analyses involving the neuroticism trait, one of the representative affective personality traits. Functional MRI was administered while subjects classified expressions of faces, and neuroticism scores were obtained from individual subjects. Significant brain activity was observed in the temporal pole (TP) during perception of both happy and sad expressions relative to neutral expressions. Correlational analyses revealed that TP activity during perception of sad expressions, but not happy expressions, correlated with the neuroticism scores. These results demonstrate differential roles for the temporal cortex in perception of happy and sad faces, and suggest that TP recruitment during understanding of negative emotions is dependent on the personality of the individuals.     

Inter-individual differences in the habitual use of cognitive reappraisal and expressive suppression are associated with variations in prefrontal cognitive control for emotional information: An event related fMRI study

Two different emotion regulation strategies, cognitive reappraisal and expressive suppression, are strongly associated with increased neural activity in the prefrontal cognitive control network. In this event-related fMRI study, we investigated whether individual differences in habitual reappraisal and suppression tendencies are related to differences in prefrontal cognitive control processes for emotional information. In order to measure cognitive control over inhibiting a dominant response to happy or sad stimuli (in favor of the opposite valence), thirty-one healthy female participants performed the Cued Emotional Conflict Task (CECT). The Emotion Regulation Questionnaire was used to measure individual differences in everyday use of emotion regulation. Results demonstrate that high reappraisers are behaviorally faster and exert more fronto-cingulate activity when inhibiting a response to sad faces (compared to happy faces, FDR corrected). On the other hand, suppression scores are not correlated with performance to CECT trials. Interestingly, suppression scores are associated with higher amygdala activation during the inhibition of a response to sad faces (compared to happy faces). These data suggest that habitual reappraisal is associated with underlying functional cognitive control processes to inhibit a dominant response to negative material. In contrast, the effort to control negative material has negative consequences in individuals who have a tendency to suppress emotions.     

Gender differences in facial reactions to facial expressions

This study explored whether males and females differ in facial muscle reactivity when exposed to facial expressions. The study also examined whether the sex of the stimulus faces differentially influences the response patterns to facial stimuli. Thus, the sex was manipulated in a 2 x 2 factorial design by exposing males and females to slides of angry and happy faces displayed by both sexes. Facial electromyographic (EMG) activity was measured from the corrugator and zygomatic muscle regions. The subjects were also required to rate the stimuli on different dimensions. The results showed that angry faces evoked increased corrugator activity whereas happy faces evoked increased zygomatic activity. As predicted, these effects were more pronounced for females, particularly for the response to happy faces. Interestingly, there were no facial EMG effects for gender of stimulus. It was further found that males and females perceived the stimuli similarly. The results are consistent with previous findings indicating that females are more facially reactive than are males.     

Visual mismatch negativity elicited by facial expressions under non-attentional condition

A modified "cross-modal delayed response" paradigm was used to investigate putative processing of face expression in the absence of focused attention to the face. Neutral, happy and sad faces were presented during intervals occurring between a tone and a response imperative signal (a faint click), while subjects were instructed to discriminate the location of the tone as quickly and accurately as possible and to ignore the faces. A neutral face was presented in 80% of the trials whereas the happy and sad faces were presented in the remaining trials - 10%, respectively. Expression mismatch negativity (EMMN) was obtained by subtracting the ERP elicited by neutral faces from that elicited by sad faces or happy faces. The EMMN started from around 120 ms (sad) and 110 ms (happy) lasting up to 430 ms (sad) and 360 ms (happy) post-stimulus. The EMMN elicited by sad faces was more negative than that elicited by happy faces. Both EMMNs distributed over posterior areas and covered larger areas in the right than in the left hemisphere sites (especially for happy EMMN).     

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.     

Infants' neutral facial expressions elicit the strongest initial attentional bias in adults: Behavioral and electrophysiological evidence

Recent studies that used adult faces as the baseline have revealed that attentional bias toward infant faces is the strongest for neutral expressions than for happy and sad expressions. However, the time course of the strongest attentional bias toward infant neutral expressions is unclear. To clarify this time course, we combined a behavioral dot-probe task with electrophysiological event-related potentials (ERPs) to measure adults' responses to infant and adult faces with happy, neutral, and sad expressions derived from the same face. The results indicated that compared with the corresponding expressions in adult faces, attentional bias toward infant faces with various expressions resulted in different patterns during rapid and prolonged attention stages. In particular, first, neutral expressions in infant faces elicited greater behavioral attentional bias and P1 responses than happy and sad ones did. Second, sad expressions in infant faces elicited greater N170 responses than neutral and happy ones did; notably, sad expressions elicited greater N170 responses in the left hemisphere in women than in men. Third, late positive potential (LPP) responses were greater for infant faces than for adult faces under each expression condition. Thus, we propose a three-stage model of attentional allocation patterns that reveals the time course of attentional bias toward infant faces with various expressions. This model highlights the prominent role of neutral facial expressions in the attentional bias toward infant faces.     

Impaired perceptual processing of facial expression categorization in social anhedonia

The current event-related potential study investigated the perceptual processing of the categorization advantage of happy over sad faces in social anhedonia with a nonclinical sample. A high social anhedonia (HSA, N = 25) group and a low social anhedonia (LSA, N = 27) group performed a facial expression categorization task during which they classified facial expressions (happy, neutral, sad), irrespective of face orientation (upright, upside-down). Behaviorally, happy faces were identified more quickly than sad ones in the upright but not inverted orientation. Electrophysiologically, the LSA group showed earlier N170 latencies for happy than for sad faces in the upright but not upside-down orientation, whereas the HSA group did not show any expression effect on N170 latencies. Moreover, N170 and P2 amplitude results revealed that HSA relative to LSA individuals showed delayed neural discrimination between happy and sad faces. These results suggest that social anhedonia is associated with a deficit of perceptual processing during facial expression categorization.     

Threat sensitivity as assessed by automatic amygdala response to fearful faces predicts speed of visual search for facial expression

It has been argued that the amygdala represents an integral component of a vigilance system that is primarily involved in the perception of ambiguous stimuli of biological relevance. The present investigation was conducted to examine the relationship between automatic amygdala responsivity to fearful faces which may be interpreted as an index of trait-like threat sensitivity and spatial processing characteristics of facial emotions. During 3T fMRI scanning, pictures of human faces bearing fearful, angry, and happy expressions were presented to 20 healthy volunteers using a backward masking procedure based on neutral facial expressions. Subsequently, a computer-based face-in-the-crowd task using schematic face stimuli was administered. The neural response of the (right) amygdala to masked fearful faces correlated consistently with response speed to negative and neutral faces. Neither amygdala activation during the masked presentation of angry faces nor amygdala activation during the presentation of happy faces was correlated with any of the response latencies in the face-in-the-crowd task. Our results suggest that amygdala responsivity to masked facial expression is differentially related to the general visual search speed for facial expression. Neurobiologically defined threat sensitivity seems to represent an important determinant of visual scanning behaviour.     

Nonconscious associative learning: Pavlovian conditioning of skin conductance responses to masked fear-relevant facial stimuli

We examined the possibility of nonconscious associative learning in a context of skin conductance conditioning, using emotional facial expressions as stimuli. In the first experiment, subjects were conditioned to a backwardly masked angry face that was followed by electric shock, with a masked happy face as the nonreinforced stimulus. In spite of the effectively masked conditioned stimuli, differential conditioned skin conductance responses were observed in a subsequent nonmasked extinction phase. This effect could not be attributed to differential sensitization or pseudo-conditioning. In the second experiment, the differential responding during extinction was replicated with angry but not with happy faces as conditioned stimuli. It was concluded that with fear-relevant facial expressions as the conditioned stimulus, associative learning was possible even in conditions where the subjects remained unaware of the conditioned stimulus and its relationship to the unconditioned stimulus.     

The influence of stimulus valence on perceptual processing of facial expressions and subsequent response inhibition

The constant interplay between affective processing and cognitive control supports emotion regulation and appropriate social functioning. Even when affective stimuli are processed implicitly, threat-related stimuli are prioritized in the earliest stages of processing; yet, it remains unclear how implicit attention to affect influences subsequent cognitive control functions. The present study evaluated the influence of affective valence on early perceptual processes and subsequent response inhibition in a context where affective properties of the stimuli (facial expressions) were not critical for performing the task. Participants (N = 32) completed an affective stop-signal task (SST) while their scalp EEGs were recorded. The SST assessed response inhibition while participants implicitly attended to happy and afraid facial expressions that were matched for level of arousal. Behavioral performance was measured via response time and accuracy while physiological response was measured via the P100, N170, and N200/P300 ERP components. Decreased gender discrimination accuracy, delayed P100 latency, and more negative N170 amplitude were observed for afraid faces compared to happy faces, suggesting a shift in processing with respect to face valence. However, differences in stopping accuracy or N200/P300 ERP components during response inhibition were not observed, pointing to top-down cognitive processes likely being recruited to override the early automatic response to prioritize threat-related stimuli. Findings highlight that, in this implicit affective attention task, threat-related stimuli are prioritized early during processing, but implicitly attending to differentially valenced stimuli did not modulate subsequent cognitive control functions.     

Modulation of facial reactions to avatar emotional faces by nonconscious competition priming

To investigate whether subliminally priming for competition influences facial reactions to facial emotional displays, 49 participants were either subliminally competition primed or neutrally primed. Thereafter, they viewed computer generated avatar faces with happy, neutral, and sad expressions while Corrugator supercilii and Zygomaticus major reactions were recorded. Results revealed facial mimicry to happy and sad faces in the neutrally primed group but not the competition primed group. Furthermore, subliminal competition priming enhanced Corrugator supercilii activity after an initial relaxation while viewing happy faces. An impression formation task revealed counter empathic effects confirming successful competition priming. Overall, results indicate that nonconscious processes influence a presumably nonconscious behavior.     

Emotional deficit in subjects with psychopathic tendencies as assessed by the Minnesota Multiphasic Personality Inventory-2: an event-related potentials study

On the basis of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), 20 male students were separated in low (LP) versus high (HP) subjects with psychopathic tendencies. Pictures from the Ekman and Friesen series were used in an event-related potentials study to investigate the neurophysiological correlates of the emotional deficit described in psychopathy. Subjects were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy, sad or fearful faces amongst a train of standard stimuli (neutral faces). Behavioral results suggest that LP subjects are more efficient in the detection of emotional deviant faces. This emotional deficit was neurophysiologically indexed, in HP subjects, by a decreased N300 component, which is supposed to be particularly sensitive to affective features of stimuli rather than to physical characteristics. Moreover, independently of the nature of the deviant faces, the P3a component shows an earlier latency in the HP group as compared to the LP group, whereas the reversed pattern was shown for the P3b component. Implications of these results were discussed.     

Pupillary reactivity to negative stimuli prospectively predicts recurrence of major depressive disorder in women

There is a large body of research supporting the association between disrupted physiological reactivity to negative stimuli and depression. The present study aimed to examine whether physiological reactivity to emotional stimuli, assessed via pupil dilation, served as a biological marker of risk for depression recurrence among individuals who are known to be at a higher risk due to having previous history of depression. Participants were 57 women with a history of major depressive disorder (MDD). Pupil dilation to angry, happy, sad, and neutral faces was recorded. Participants' diagnoses and symptoms were assessed 24 months after the initial assessment. We found that women's pupillary reactivity to negative (sad or angry faces) but not positive stimuli prospectively predicted MDD recurrence. Additionally, we found that both hyper‐ and hypopupillary reactivity to angry faces predicted risk for MDD recurrence. These findings suggest that disrupted physiological response to negative stimuli indexed via pupillary dilation could serve as a physiological marker of MDD risk, thus presenting clinicians with a convenient and inexpensive method to predict which of the at‐risk women are more likely to experience depression recurrence.     

Face-specific event-related potential in humans is independent from facial expression.

A face-specific brain EEG potential at approximately 160 ms after stimulus presentation has recently been described by various research groups. Most of these studies analysed this face-specific brain potential using smiling faces as stimuli. In electrophysiological studies, however, differences in amplitude due to the emotional valence of the stimuli were described as early as 100 ms after stimulus presentation. In order to investigate the effect of facial expressions with different emotional content on face-specific brain EEG potentials, event-related potentials (ERPs) to faces with sad, happy and neutral expressions were compared to ERPs elicited with buildings in 16 healthy subjects. A face-specific potential at vertex approximately 160 ms after stimulus presentation has been verified in the present study. No significant differences in latency or amplitude of this component were found for different facial expressions.     

Does the emotional go/no-go task really measure behavioral inhibition?: Convergence with measures on a non-emotional analog

This study tested the convergence of behavioral inhibition measures across emotional and non-emotional versions of the same go/no-go task in 85 college students. The two tasks differed only in the stimuli used for trial cues (i.e., circles versus facial expressions). Moderate correlations (r=.51-.56) between commission errors across the emotional and non-emotional tasks support the construct validity of behavioral inhibition. Further, parametric manipulation of preceding context had comparable effects on performance on the two tasks. Responses were slower and more variable, commission errors were more numerous, and perceptual sensitivity was lower on the emotional than the non-emotional task. A bias for happy faces on the emotional task resulted in faster responses and more commission errors for happy than sad faces despite marginally greater sensitivity for the latter. These results suggest that the basic neuropsychological constructs of the original go/no-go task were preserved in the emotional adaptation.     

Crossmodal transfer of emotion by music

Music is one of the most powerful elicitors of subjective emotion, yet it is not clear whether emotions elicited by music are similar to emotions elicited by visual stimuli. This leads to an open question: can music-elicited emotion be transferred to and/or influence subsequent vision-elicited emotional processing? Here we addressed this question by investigating processing of emotional faces (neutral, happy and sad) primed by short excerpts of musical stimuli (happy and sad). Our behavioural experiment showed a significant effect of musical priming: prior listening to a happy (sad) music enhanced the perceived happiness (sadness) of a face irrespective of facial emotion. Further, this musical priming-induced effect was largest for neutral face. Our electrophysiological experiment showed that such crossmodal priming effects were manifested by event related brain potential components at a very early (within 100 ms post-stimulus) stages of neuronal information processing. Altogether, these results offer new insight into the crossmodal nature of music and its ability to transfer emotion to visual modality.