Ute Habel

Amygdala activation and facial expressions: explicit emotion discrimination versus implicit emotion processing.

Emotion recognition is essential for social interaction and communication and is a capacity in which the amygdala plays a central role. So far, neuroimaging results have been inconsistent as to whether the amygdala is more active during explicit or incidental facial emotion processing. In consideration of its functionality in fast automatic evaluation of stimuli and involvement in higher-order conscious processing, we hypothesize a similar response to the emotional faces presented regardless of attentional focus. Using high field functional magnetic resonance imaging (fMRI) specifically optimized for ventral brain regions we show strong and robust amygdala activation for explicit and implicit processing of emotional facial expressions in 29 healthy subjects. Bilateral amygdala activation was, however, significantly greater when subjects were asked to recognize the emotion (explicit condition) than when required to discern the age (implicit condition). A significant correlation between amygdala activation and emotion recognition, but not age discrimination performance, emphasizes the amygdalas enhanced role during conscious emotion processing.

General and specific responsiveness of the amygdala during explicit emotion recognition in females and males

BackgroundThe ability to recognize emotions in facial expressions relies on an extensive neural network with the amygdala as the key node as has typically been demonstrated for the processing of fearful stimuli. A sufficient characterization of the factors influencing and modulating amygdala function, however, has not been reached now. Due to lacking or diverging results on its involvement in recognizing all or only certain negative emotions, the influence of gender or ethnicity is still under debate.This high-resolution fMRI study addresses some of the relevant parameters, such as emotional valence, gender and poser ethnicity on amygdala activation during facial emotion recognition in 50 Caucasian subjects. Stimuli were color photographs of emotional Caucasian and African American faces.ResultsBilateral amygdala activation was obtained to all emotional expressions (anger, disgust, fear, happy, and sad) and neutral faces across all subjects. However, only in males a significant correlation of amygdala activation and behavioral response to fearful stimuli was observed, indicating higher amygdala responses with better fear recognition, thus pointing to subtle gender differences. No significant influence of poser ethnicity on amygdala activation occurred, but analysis of recognition accuracy revealed a significant impact of poser ethnicity that was emotion-dependent.ConclusionApplying high-resolution fMRI while subjects were performing an explicit emotion recognition task revealed bilateral amygdala activation to all emotions presented and neutral expressions. This mechanism seems to operate similarly in healthy females and males and for both in-group and out-group ethnicities. Our results support the assumption that an intact amygdala response is fundamental in the processing of these salient stimuli due to its relevance detecting function.

Modulating the processing of emotional stimuli by cognitive demand

Emotional processing is influenced by cognitive processes and vice versa, indicating a profound interaction of these domains. The investigation of the neural mechanisms underlying this interaction is not only highly relevant for understanding the organization of human brain function. Rather, it may also help in understanding dysregulated emotions in affective disorders and in elucidating the neurobiology of cognitive behavioural therapy (e.g. in borderline personality disorder), which aims at modulating dysfunctional emotion processes by cognitive techniques, such as restructuring. In the majority of earlier studies investigating the interaction of emotions and cognition, the main focus has been on the investigation of the effects of emotional stimuli or, more general, emotional processing, e.g. instituted by emotional material that needed to be processed, on cognitive performance and neural activation patterns. Here we pursued the opposite approach and investigated the modulation of implicit processing of emotional stimuli by cognitive demands using an event-related functional magnetic resonance imaging--study on a motor short-term memory paradigm with emotional interferences. Subjects were visually presented a finger-sequence consisting either of four (easy condition) or six (difficult condition) items, which they had to memorize. After a short pause positive, negative or neutral International affective picture system pictures or a green dot (as control condition) were presented. Subjects were instructed to reproduce the memorized sequence manually as soon as the picture disappeared. Analysis showed that with increasing cognitive demand (long relative to short sequences), neural responses to emotional pictures were significantly reduced in amygdala and orbitofrontal cortex. In contrast, the more difficult task evoked stronger activation in a widespread frontoparietal network. As stimuli were task-relevant go-cues and hence had to be processed perceptually, we would interpret this as a specific attenuation of affective responses by concurrent cognitive processing--potentially reflecting a relocation of resources mediated by the frontoparietal network.

Amygdala activation during recognition of emotions in a foreign ethnic group is associated with duration of stay

Abstract Cultural differences in emotion recognition performance have frequently been reported, whereby duration of stay in a foreign culture seems to be a crucial factor. Furthermore, cultural aspects influence the neural correlates of face and emotion processing thereby also affecting the response of the amygdala. Here, the exposure to a foreign culture and its influence on the cerebral correlates of facial emotion recognition were examined in 24 Asian and 24 age-matched European males. Subjects performed an explicit emotion recognition task and were imaged with a 3 T MR-scanner. Results demonstrate a significant cultural influence on the specific recognition of disgust and anger, with higher accuracy among the Europeans, while the functional data indicate generally elevated amygdala activation in Asians compared to Europeans. Moreover, a significant inverse correlation between duration of stay and amygdala response emerged, with stronger activation in those subjects with shorter duration of stay in Europe. The observed amygdala hyperactivation in Asians may reflect novelty aspects but might also be associated with greater effort and motivation in immigrants, thus it possibly reflects one neural correlate of the “alien-effect”. We conclude that exposure to a foreign culture and duration of stay affect the behavioral and neural response to facial expressions of emotions.

Neural Correlates of Moral Reasoning in Autism Spectrum Disorder

In our study, we tried to clarify whether patients with autism spectrum disorder (ASD) reveal different moral decision patterns as compared to healthy subjects and whether common social interaction difficulties in ASD are reflected in altered brain activation during different aspects of moral reasoning. 28 patients with high-functioning ASD and 28 healthy subjects matched for gender, age and education took part in an event-related functional magnetic resonance imaging study. Participants were confronted with textual dilemma situations followed by proposed solutions to which they could agree or disagree. On a neural level, moral decision making was associated with activation in anterior medial prefrontal regions, the temporo-parietal junction and the precuneus for both groups. However, while patients and healthy controls did not exhibit significant behavioral differences, ASD patients showed decreased activation in limbic regions, particularly the amygdala, as well as increased activation in the anterior and the posterior cingulate gyrus during moral reasoning. Alterations of brain activation in patients might thus indicate specific impairments in empathy. However, activation increases in brain regions associated with the default mode network and self-referential cognition also provide evidence for an altered way of patients cerebral processing with regard to decision making based on social information.

Culture but not gender modulates amygdala activation during explicit emotion recognition

BackgroundMounting evidence indicates that humans have significant difficulties in understanding emotional expressions from individuals of different ethnic backgrounds, leading to reduced recognition accuracy and stronger amygdala activation. However, the impact of gender on the behavioral and neural reactions during the initial phase of cultural assimilation has not been addressed. Therefore, we investigated 24 Asians students (12 females) and 24 age-matched European students (12 females) during an explicit emotion recognition task, using Caucasian facial expressions only, on a high-field MRI scanner.ResultsAnalysis of functional data revealed bilateral amygdala activation to emotional expressions in Asian and European subjects. However, in the Asian sample, a stronger response of the amygdala emerged and was paralleled by reduced recognition accuracy, particularly for angry male faces. Moreover, no significant gender difference emerged. We also observed a significant inverse correlation between duration of stay and amygdala activation.ConclusionIn this study we investigated the “alien-effect” as an initial problem during cultural assimilation and examined this effect on a behavioral and neural level. This study has revealed bilateral amygdala activation to emotional expressions in Asian and European females and males. In the Asian sample, a stronger response of the amygdala bilaterally was observed and this was paralleled by reduced performance, especially for anger and disgust depicted by male expressions. However, no gender difference occurred. Taken together, while gender exerts only a subtle effect, culture and duration of stay as well as gender of poser are shown to be relevant factors for emotion processing, influencing not only behavioral but also neural responses in female and male immigrants.

Diagnostik und Symptomatik von Alkoholintoxikation, schädlichem Gebrauch und Alkoholabhängigkeit

Differentialdiagnostisch trennt man die kurzfristige Wirkung eines ubermasigen Alkoholkonsums (Alkoholintoxikation) von langer dauerndem, chronisch uberhohtem schadlichem Gebrauch oder der Abhangigkeit sowie ihren jeweiligen korperlichen und psychischen Folgen. Diese Termini lassen sich klinisch anhand der Quantitat, Dauer, Intensitat und Frequenz der Alkoholeinnahme definieren und differenzieren.

Immediate and delayed neuroendocrine responses to social exclusion in males and females

Social exclusion is a complex phenomenon, with wide-ranging immediate and delayed effects on well-being, hormone levels, brain activation and motivational behavior. Building upon previous work, the current fMRI study investigated affective, endocrine and neural responses to social exclusion in a more naturalistic Cyberball task in 40 males and 40 females. As expected, social exclusion elicited well-documented affective and neural responses, i.e., increased anger and distress, as well as increased exclusion-related activation of the anterior insula, the posterior-medial frontal cortex and the orbitofrontal cortex. Cortisol and testosterone decreased over the course of the experiment, whereas progesterone showed no changes. Hormone levels were not correlated with subjective affect, but they were related to exclusion-induced neural responses. Exclusion-related activation in frontal areas was associated with decreases in cortisol and increases in testosterone until recovery. Given that results were largely independent of sex, the current findings have important implications regarding between-sex vs. within-sex variations and the conceptualization of state vs. trait neuroendocrine functions in social neuroscience.

Reaktionen auf schwere belastungen und anpassungsstörungen (F43)

Reaktionen auf schwere Belastungen und Anpassungsstorungen stehen in zeitlichem Zusammenhang mit traumatischen Ereignissen oder belastenden Lebensumstanden, ohne die die Erkrankungen nicht aufgetreten waren. Die ICD-10 fasst hierunter im Wesentlichen die akute Belastungsreaktion, die posttraumatische Belastungsstorung (PTBS) und Anpassungsstorungen. Therapeutischer Schwerpunkt liegt auf den psychotherapeutischen Verfahren. Bei akuter Belastungsreaktion und Anpassungsstorungen sind stutzende Gesprache oft ausreichend. Bei PTBS ist die Wirksamkeit der traumafokussierten kognitiven Verhaltenstherapie am besten und partiell auch die Eye-Movement-Desensitization-and-Reprocessing-Therapie belegt; empfohlen wird ein phasenorientiertes Vorgehen zunachst mit Stabilisierung, dann Traumaexposition. Generell sollte bei Traumata nicht zu fruh interveniert werden und nur bei Vorliegen zusatzlicher Risikofaktoren. Es wird von einer routinemasigen Anwendung des Debriefings nach Katastrophen abgeraten.

Rekrutierung von Studienteilnehmern

Die sorgfaltige Rekrutierung von geeigneten Studienteilnehmern ist die Basis einer jeden fundierten (funktionellen) Magnetresonanztomographie-(fMRT-)Studie. Dies gilt insbesondere im klinischen Rahmen. Dennoch wird der vorhergehenden angemessenen Abwagung wesentlicher Ein- und Ausschlusskriterien oft zu wenig Zeit und Uberlegung gewidmet. Eine nachlassige Auswahl der Probanden kann sich jedoch gravierend auf die Ergebnisse auswirken und damit auch die Aussagekraft der bestdurchdachten Paradigmen und Designs zunichte machen. Eine sorgfaltige Rekrutierung fur fMRT-Studien bedarf eines nicht zu unterschatzenden Zeitaufwandes.