Stimulus arousal drives amygdalar responses to emotional expressions across sensory modalities.

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.

Early brain responses to affective faces: A simultaneous EEG-fMRI study.

The spatio-temporal neural basis of earliest differentiation between emotional and neutral facial expressions is a matter of debate. The present study used concurrent electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) in order to investigate the 'when' and 'where' of earliest prioritization of emotional over neutral expressions. We measured event-related potentials (ERPs) and blood oxygen dependent (BOLD) signal changes in response to facial expressions of varying emotional intensity and different valence categories.

Effects of Intensity of Facial Expressions on Amygdalar Activation Independently of Valence.

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.

Loud and angry: sound intensity modulates amygdala activation to angry voices in social anxiety disorder.

Angry expressions of both voices and faces represent disorder-relevant stimuli in social anxiety disorder (SAD). Although individuals with SAD show greater amygdala activation to angry faces, previous work has failed to find comparable effects for angry voices. Here, we investigated whether voice sound-intensity, a modulator of a voice's threat-relevance, affects brain responses to angry prosody in SAD.

Effects of emotional intensity under perceptual load: An event-related potentials (ERPs) study.

Effects of emotional intensity and valence on visual event-related potentials (ERPs) are still poorly understood, in particular in the context of limited attentional resources. In the present EEG study, we investigated the effect of emotional intensity of different emotional facial expressions on P1, N170, early posterior negativity (EPN) and late positive potential (LPP) while varying the amount of available attentional resources. A new stimulus set comprising 90 full color pictures of neutral, happy (low, high intensity), and angry (low, high intensity) expressions was developed.

Neural basis of processing threatening voices in a crowded auditory world.

In real world situations, we typically listen to voice prosody against a background crowded with auditory stimuli. Voices and background can both contain behaviorally relevant features and both can be selectively in the focus of attention. Adequate responses to threat-related voices under such conditions require that the brain unmixes reciprocally masked features depending on variable cognitive resources.

Brain activation to briefly presented emotional words: effects of stimulus awareness.

It is unknown to what extent briefly presented emotional words can be processed without awareness. By means of two independent functional magnetic resonance imaging studies, using either a block or an event-related design, we investigated brain activation to very briefly presented threat related and neutral words during two backward masking conditions (with and without gap between target and mask). In both experiments, emotional words were perceived during the supraliminal "with gap" condition, but they were not recognized during the subliminal "without gap" condition, as indicated by signal detection theory analysis.

Neural correlates of anticipation and processing of performance feedback in social anxiety.

Fear of negative evaluation, such as negative social performance feedback, is the core symptom of social anxiety. The present study investigated the neural correlates of anticipation and perception of social performance feedback in social anxiety. High (HSA) and low (LSA) socially anxious individuals were asked to give a speech on a personally relevant topic and received standardized but appropriate expert performance feedback in a succeeding experimental session in which neural activity was measured during anticipation and presentation of negative and positive performance feedback concerning the speech performance, or a neutral feedback-unrelated control condition.

Effects of social context on feedback-related activity in the human ventral striatum.

It is now well established that activation of the ventral striatum (VS) encodes feedback related information, in particular, aspects of feedback validity, reward magnitude, and reward probability. More recent findings also point toward a role of VS in encoding social context of feedback processing. Here, we investigated the effect of social observation on neural correlates of feedback processing.

Effects of gaze direction, head orientation and valence of facial expression on amygdala activity.

There is increasing evidence for a role of the amygdala in processing gaze direction and emotional relevance of faces. In this event-related functional magnetic resonance study we investigated amygdala responses while we orthogonally manipulated head direction, gaze direction and facial expression (angry, happy and neutral). This allowed us to investigate effects of stimulus ambiguity, low-level factors and non-emotional factors on amygdala activation.

Automatic neural processing of disorder-related stimuli in social anxiety disorder: faces and more.

It has been proposed that social anxiety disorder (SAD) is associated with automatic information processing biases resulting in hypersensitivity to signals of social threat such as negative facial expressions. However, the nature and extent of automatic processes in SAD on the behavioral and neural level is not entirely clear yet. The present review summarizes neuroscientific findings on automatic processing of facial threat but also other disorder-related stimuli such as emotional prosody or negative words in SAD.

Amygdala activation to fearful faces under attentional load.

While some functional imaging studies suggested an automatic activation of the amygdala to fearful vs. neutral faces, recent studies showed the absence of amygdala activation to fearful faces under high attentional load induced by distracting tasks. The present fMRI study investigated whether this outcome can be modulated by changing the saliency of the eyes of fearful faces.

Processing of angry voices is modulated by visual load.

Visual perceptual load has been shown to modulate brain activation to emotional facial expressions. However, it is unknown whether cross-modal effects of visual perceptual load on brain activation to threat-related auditory stimuli also exist. The current fMRI study investigated brain responses to angry and neutral voices while subjects had to solve an easy or a demanding visual task.

Awareness modulates responses of the amygdala and the visual cortex to highly arousing visual threat.

It is still a matter of debate under which conditions the neural processing of emotional stimuli can occur without conscious awareness. Using functional magnetic resonance imaging, we investigated brain responses to highly arousing threat-related versus neutral pictures which were presented very briefly during two backward-masking conditions resulting in either subliminal or supraliminal stimulus processing. Signal detection analysis confirmed the successful experimental manipulation of awareness that effectively prevented stimulus recognition during the subliminal condition.

Neural mechanisms of the automatic processing of emotional information from faces and voices.

Theoretical accounts suggest an increased and automatic neural processing of emotional, especially threat-related, facial expressions and emotional prosody. In line with this assumption, several functional imaging studies showed activation to threat-related faces and voices in subcortical and cortical brain areas during attentional distraction or unconscious stimulus processing. Furthermore, electrophysiological studies provided evidence for automatic early brain responses to emotional facial expressions and emotional prosody.

Visual attention modulates brain activation to angry voices.

In accordance with influential models proposing prioritized processing of threat, previous studies have shown automatic brain responses to angry prosody in the amygdala and the auditory cortex under auditory distraction conditions. However, it is unknown whether the automatic processing of angry prosody is also observed during cross-modal distraction. The current fMRI study investigated brain responses to angry versus neutral prosodic stimuli during visual distraction.

Amygdala activation to threat under attentional load in individuals with anxiety disorder.

Background: Previous studies in healthy subjects have shown that strong attentional distraction prevents the amygdala from responding to threat stimuli. Here, we investigated the effects of attentional load on amygdala activation to threat-related stimuli in individuals suffering from an anxiety disorder.

Methods: During functional magnetic resonance imaging, spider-phobicand healthy control subjects were presented with phobia-related and neutral stimuli while performing a distraction task with varying perceptual load (high vs low).

The volatility of the amygdala response to masked fearful eyes.

Recently, it has been suggested that backwardly masked, and thus subliminally presented, fearful eyes are processed by the amygdala. Here, we investigated in four functional magnetic resonance imaging experiments whether the amygdala responds to subliminally presented fearful eyes per se or whether an interaction of masked eyes with the masks or with parts of the masks used for backward masking might be responsible for the amygdala activation. In these experiments, we varied the mask as well as the position of the target eyes.