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Ergebnisse 3 Einträge
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Perceiving a first target stimulus (T1) in a rapid serial visual presentation stream results in a transient impairment in detecting a second target (T2). This "attentional blink" is modulated by the emotional relevance of T1 and T2. The present experiment examined the neural underpinnings of the emotional modulation of the attentional blink. Behaviorally, the attentional blink was reduced for emotional T2 while emotional T1 led to a prolonged attentional blink. Using functional magnetic resonance imaging, we observed amygdala activation associated with the reduced attentional blink for emotional T2 in the face of neutral T1. The prolonged attentional blink following emotional T1 was correlated with enhanced activity in a cortical network including the anterior cingulate cortex, the insula and the orbitofrontal cortex. These results suggest that brain areas previously implicated in rather reflexive emotional reactions are responsible for the reduced attentional blink for emotional T2 whereas neural structures previously related to higher level processing of emotional information mediate the prolonged attentional blink following emotional T1.
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Previously, we observed cortisol induced enhancement of neural fear acquisition in women. Yet, less is known about cortisol effects on neural fear extinction. Via differential fear conditioning, we explored cortisol effects on acquisition and extinction. Twenty contingency aware women taking monophasic oral contraceptives were included; 10 received placebo, 10 cortisol before conditioning. Group differences emerged in anterior cingulate cortex (ACC), hippocampus, and--as trend--in insula and thalamus during acquisition and in hippocampus, thalamus, and--as trend--in amygdala, insula, and ACC during extinction. During acquisition group differences were due to higher responses to the CS+ than to the CS- in the cortisol group. Notably, during extinction, group differences were due to higher responses to the CS- than to the CS+ in this group. Thus, cortisol induced a fear acquisition and extinction specific enhanced neural differentiation.
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In an fMRI study, effects of contingency awareness on conditioned responses were assessed in three groups comprising 118 subjects. A differential fear-conditioning paradigm with visual conditioned stimuli, an electrical unconditioned stimulus and two distractors was applied. The instructed aware group was informed about the contingencies, whereas the distractors prevented contingency detection in the unaware group. The third group (learned aware) was not informed about the contingencies, but learned them despite the distractors. Main effects of contingency awareness on conditioned responses emerged in several brain structures. Post hoc tests revealed differential dorsal anterior cingulate, insula and ventral striatum responses in aware conditioning only, whereas the amygdala was activated independent of contingency awareness. Differential responses of the hippocampus were specifically observed in learned aware subjects, indicating a role in the development of contingency awareness. The orbitofrontal cortex showed varying response patterns: lateral structures showed higher responses in instructed aware than unaware subjects, the opposite was true for medial parts. Conditioned subjective and electrodermal responses emerged only in the two aware groups. These results confirm the independence of conditioned amygdala responses from contingency awareness and indicate specific neural circuits for different aspects of fear acquisition in unaware, learned aware and instructed aware subjects.
Erkunden
Team
- Vaitl (3)
Eintragsart
Sprache
- Englisch (3)
Thema
- Image Processing, Computer-Assisted
- Adolescent (1)
- Adult (3)
- Amygdala/physiology (1)
- Analysis of Variance (1)
- Arousal/physiology (1)
- Association Learning/*physiology (1)
- Attention/*physiology (1)
- Awareness/physiology (1)
- Awareness/*physiology (1)
- Blinking/*physiology (1)
- Brain Mapping (1)
- Brain/physiology (1)
- Brain/*physiology (1)
- Cerebral Cortex/physiology (1)
- Cerebral Cortex/*physiology (1)
- Conditioning, Classical/*physiology (1)
- Conditioning, Psychological/*physiology (1)
- Double-Blind Method (1)
- Electric Stimulation (2)
- Emotions/*physiology (1)
- Extinction, Psychological/*physiology (1)
- Fear/*physiology (1)
- Fear/*psychology (1)
- Female (3)
- Fixation, Ocular/physiology (1)
- Frontal Lobe/physiology (1)
- Galvanic Skin Response/*physiology (1)
- Humans (3)
- Hydrocortisone/analysis/*metabolism (1)
- Learning/physiology (1)
- Magnetic Resonance Imaging (3)
- Male (2)
- Nerve Net/*physiology (1)
- Occipital Lobe/physiology (1)
- Photic Stimulation (3)
- Reaction Time/physiology (1)
- Saliva/chemistry (1)
- Surveys and Questionnaires (1)
- Young Adult (2)