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Dissertation zugänglich unter
The Attentional Bias to Emotion
Der Aufmerksamkeitsbias zu Emotionaler Information
Dokument 1.pdf (18.035 KB)
Emotionales Verhalten , Aufmerksamkeit , Visuelles System , Neurowissenschaften , Magnetoencephalographie , Elektroencephalographie
Freie Schlagwörter (Deutsch):
Emotion , Oszillationen , Aufmerksamkeitsbias , intrakranielles EEG
Freie Schlagwörter (Englisch):
Emotion , Attentional Bias , Oscillations, MEG, intracranial EEG
77.46 , 77.37 , 77.50
Engel, Andreas K. (Prof. Dr.)
Tag der mündlichen Prüfung:
Kurzfassung auf Englisch:
Emotionally significant stimuli successfully compete for attentional resources with current, goal-directed behavior. This attentional bias entails an adaptive advantage and is particularly strong for negative, threat-related information, such as fearful facial expressions. Models of the attentional bias to threat, implicating the amygdala in the detection of and prefrontal cortex (PFC) and anterior cingulate in the attentional control over emotionally significant stimuli, have received large empirical support.
Temporal synchronization of neuronal activity indicates network interactions and may underlie the attentional threat bias. Synchronization in the theta and gamma band has been associated with the detection of emotionally significant, task-irrelevant stimuli in the amygdala and medial temporal lobe. Attentional selection in general has been reliably associated with frequency-specific synchronization of neuronal activity in frontal and parietal regions. However, it is unknown whether attentional control over emotional stimuli engages frequency-specific changes in the PFC. Individual differences, such as increased anxiety levels or genetic variants, are associated with elevated threat biases and modulate activation in this circuitry. Thus, it is expected that such individual differences are also associated with frequency-specific changes in those brain regions. The three studies of this thesis assessed attentional capture by emotional facial expressions in three domains of attention. Two of them investigated the role of synchronized neuronal activity by employing intracranial EEG and MEG.
Study I investigated in seven successive experiments how emotional facial expressions modulated temporal fluctuation of attention in an attentional blink (AB) paradigm. The AB denotes a period of impaired attention when a second target briefly follows a first target in a stream of rapidly presented stimuli. It was expected that emotional facial expressions were more easily detected than neutral faces during the blink interval. Since the AB was absent or shallow in Experiments 1 and 2, respectively, the similarity between the two targets (Experiment 3), the similarity of targets and distractors (Experiment 4-6), and the task relevance of the emotional expression (Experiment 7) was manipulated. Increased similarity between targets and distractors resulted in a stronger AB for neutral faces relative to emotional faces. Task relevance of emotional expression in Experiment 7 did not have a stronger impact on AB magnitude than increased target-distractor similarity.
Study II exploited the good spatial and temporal resolution of iEEG to directly record from the fusiform gyrus, OFC, insula, and amygdala of patients with pharmaco-resistant epilepsy to uncover whether voluntary, endogenous attention (manipulated by the task) and reflexive, exogenous attention (manipulated by facial expressions) affect temporal synchronization in all regions equally (particularly in high frequencies > 30 Hz). Facial expressions were task-relevant in the first but task-irrelevant in the second task. When facial expressions were task-relevant, stronger changes in stimulus-induced high-frequency activity in all investigated regions were observed. The latencies revealed that the activation was temporally coordinated across the network, rather than serially proceeding along a processing hierarchy. Contrary to the initial hypothesis, differences between fearful and neutral faces were rarely observed. These results show that endogenous attention operates along the whole face-processing network, and that these effects are best captured by changes in high-frequency activity.
Finally, Study III employed MEG and a variant of a dot probe task to uncover whether frequency-specific neuronal activity was modulated by the allocation of attention towards task-irrelevant fearful face distractors. The participants were selected according to their genotype of the serotonin-transporter-linked polymorphic region (5-HTTLPR), as variation in this gene is associated with elevated anxiety levels. Lateralized attention effects to targets were found over parieto-occipital sensors in the theta, alpha, and gamma band. Interestingly, fearful face distractors led to an increase of gamma-band activity in the right fronto-parietal attention network when presented at the same side as targets. Participants with a stronger genetic disposition (i.e., carriers of the 5-HTTLPR short allele) exhibited stronger activation in the theta band in regions involved in emotion processing. Study III provides first insight that the attentional bias to threat is exerted through dynamic interactions between frontal and parietal regions. In conclusion, the present work supports the hypothesis that the attentional bias to threat is reflected in temporal synchronization of neuronal activity and established important markers for further work on this topic, especially in the domain of clinical anxiety.