The factors that drive amygdalar responses to emotionally significant stimuli are still a matter of debate – particularly the proneness of the amygdala to respond to negatively-valenced stimuli has been discussed controversially. Furthermore, it is uncertain whether the amygdala responds in a modality-general fashion or whether modality-specific idiosyncrasies exist. Therefore, the present functional magnetic resonance imaging (fMRI) study systematically investigated amygdalar responding to stimulus valence and arousal of emotional expressions across visual and auditory modalities. During scanning, participants performed a gender judgment task while prosodic and facial emotional expressions were presented. The stimuli varied in stimulus valence and arousal by including neutral, happy and angry expressions of high and low emotional intensity. Results demonstrate amygdalar activation as a function of stimulus arousal and accordingly associated emotional intensity regardless of stimulus valence. Furthermore, arousal-driven amygdalar responding did not depend on the visual and auditory modalities of emotional expressions. Thus, the current results are consistent with the notion that the amygdala codes general stimulus relevance across visual and auditory modalities irrespective of valence. In addition, whole brain analyses revealed that effects in visual and auditory areas were driven mainly by high intense emotional facial and vocal stimuli, respectively, suggesting modality-specific representations of emotional expressions in auditory and visual cortices.

Introduction: Labeling the emotional aspect of self‐unrelated stimuli (i.e., affect labeling) is a crucial strategy for implicit emotion regulation. However, it is uncertain whether affect labeling influences event‐related potential (ERP) responses (e.g., the late positive potential, LPP) to negative stimuli in comparison with control conditions in which attention is shifted to the emotional content of the stimuli (e.g., affect matching). Additionally, it is unknown whether affect labeling has a lasting effect on the processing of negative stimuli.Methods: Participants were required to label the emotion (negative or neutral) of target pictures with two words, to match the emotion with alternative pictures or to merely view the target pictures. Target pictures were presented again immediately after the regulation task. After all the target pictures had been labeled, matched and viewed, the pictures were re‐exposed for the third time.Results: The results showed that negative pictures elicited larger late LPP responses during the affect labeling task than during other tasks. However, the LPP responses were smaller for negative pictures in the affect labeling condition than in the other conditions when target pictures were re‐exposed immediately after the task. When target pictures were re‐presented again long after the regulation tasks, the LPP responses were smaller for negative stimuli with a history of affect labeling than viewing, whereas this effect did not differ between the affect labeling and matching conditions.Conclusion: The current findings suggest that affect labeling has current effects and, to some extent, has lasting effects on negative stimulus processing.

For several stimulus categories (e.g., pictures, odors and words), the arousal of both negative and positive stimuli has been shown to modulate amygdalar activation. In contrast, previous studies did not observe similar amygdalar effects in response to negative and positive facial expressions with varying intensity of facial expressions. Reasons for this discrepancy may be related to analytical strategies, experimental design and stimuli. Therefore, the present study aimed at re-investigating whether the intensity of facial expressions modulates amygdalar activation by circumventing limitations of previous research. Event-related functional magnetic resonance imaging (fMRI) was used to assess brain activation while participants observed a static neutral expression and positive (happy) and negative (angry) expressions of either high or low intensity from an ecologically valid, novel stimulus set. The ratings of arousal and intensity were highly correlated. We found that amygdalar activation followed a u-shaped activation pattern with highest activation to high intense facial expressions as compared to low intensity facial expressions and to the neutral expression irrespective of valence, suggesting a critical role of the amygdala in valence-independent arousal processing of facial expressions. Additionally, consistent with previous studies, intensity effects were also found in visual areas and generally increased activation to angry vs. happy faces were found in visual cortex and insula, indicating enhanced visual representations of high arousing facial expressions and increased visual and somatosensory representations of threat.