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We examined whether males and females differ in the intensity and laterality of their hemodynamic responses towards visual disgust and fear stimuli. Forty-one female, and 51 male subjects viewed disgust-inducing, fear-inducing and neutral pictures in an fMRI block design. Self-report data indicated that the target emotions had been elicited successfully with women responding stronger than men. While viewing the fear pictures, which depicted attacks by humans or animals, men exhibited greater activation in the bilateral amygdala and the left fusiform gyrus than women. This response pattern may reflect greater attention from males to cues of aggression in their environment. Further, the lateralization of brain activation was comparable in the two genders during both aversive picture conditions.
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Phobic responses are strong emotional reactions towards phobic objects, which can be described as a deficit in the automatic regulation of emotions. Difficulties in the voluntary cognitive control of these emotions suggest a further phobia-specific deficit in effortful emotion regulation mechanisms. The actual study is based on this emotion regulation conceptualization of specific phobias. The aim is to investigate the neural correlates of these two emotion regulation deficits in spider phobics. Sixteen spider phobic females participated in a functional magnetic resonance imaging (fMRI) study in which they were asked to voluntarily up- and down-regulate their emotions elicited by spider and generally aversive pictures with a reappraisal strategy. In line with the hypothesis concerning an automatic emotion regulation deficit, increased activity in the insula and reduced activity in the ventromedial prefrontal cortex was observed. Furthermore, phobia-specific effortful regulation within phobics was associated with altered activity in medial prefrontal cortex areas. Altogether, these results suggest that spider phobic subjects are indeed characterized by a deficit in the automatic as well as the effortful regulation of emotions elicited by phobic compared with aversive stimuli. These two forms of phobic emotion regulation deficits are associated with altered activity in different medial prefrontal cortex subregions.
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The majority of neuroimaging studies on affective processing have indicated that there are specific brain structures, which are selectively responsive to fear and disgust. Whereas the amygdala is assumed to be fear-related, the insular cortex is most likely involved in disgust processing. Since these findings are mainly a result of studies focusing exclusively either on fear, or on disgust, but rarely on both emotions together, the present experiment explored the neural effects of viewing disgusting and fear-inducing pictures in contrast to neutral pictures. This was done by means of functional magnetic resonance imaging (fMRI) with 19 subjects (nine males, ten females), who also gave affective ratings for the presented pictures. The fear and the disgust pictures were able to induce the target emotions and they received comparable valence and arousal ratings. The processing of both aversive picture types was associated with an increased brain activation in the occipital-temporal lobe, in the prefrontal cortex, and in the thalamus. The amygdala was significantly activated by disgusting, but not by fear-inducing, pictures. Thus, our data are in contrast with the idea of highly emotion-specific brain structures and rather suggest the existence of a common affective circuit.
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Fear learning is a crucial process in the pathogeneses of psychiatric disorders, which highlights the need to identify specific factors contributing to interindividual variation. We hypothesized variation in the serotonin transporter gene (5-HTTLPR) and stressful life events (SLEs) to be associated with neural correlates of fear conditioning in a sample of healthy male adults (n = 47). Subjects were exposed to a differential fear conditioning paradigm after being preselected regarding 5-HTTLPR genotype and SLEs. Individual differences in brain activity as measured by functional magnetic resonance imaging (fMRI), skin conductance responses and preference ratings were assessed. We report significant variation in neural correlates of fear conditioning as a function of 5-HTTLPR genotype. Specifically, the conditioned stimulus (CS(+)) elicited elevated activity within the fear-network (amygdala, insula, thalamus, occipital cortex) in subjects carrying two copies of the 5-HTTLPR S' allele. Moreover, our results revealed preliminary evidence for a significant gene-by-environment interaction, such as homozygous carriers of the 5-HTTLPR S' allele with a history of SLEs demonstrated elevated reactivity to the CS(+) in the occipital cortex and the insula. Our findings contribute to the current debate on 5-HTTLPR x SLEs interaction by investigating crucial alterations on an intermediate phenotype level which may convey an elevated vulnerability for the development of psychopathology.
Erkunden
Eintragsart
Sprache
- Englisch (4)
Thema
- Oxygen/blood
- Adult (3)
- Amygdala/anatomy & histology/blood supply/physiology (1)
- Animals (1)
- Attention/physiology (1)
- Brain/blood supply/pathology (1)
- Brain Mapping (2)
- *Brain Mapping (1)
- Brain/physiology (1)
- Conditioning, Classical/*physiology (1)
- DNA Mutational Analysis (1)
- Emotions/*physiology (3)
- Expressed Emotion/*physiology (1)
- Fear/*physiology (2)
- Fear/*psychology (1)
- Female (4)
- Galvanic Skin Response/genetics (1)
- Genotype (1)
- Hemodynamics/*physiology (2)
- Humans (4)
- Image Processing, Computer-Assisted (2)
- Image Processing, Computer-Assisted/methods (1)
- *Individuality (1)
- Life Change Events (1)
- Magnetic Resonance Imaging (2)
- Magnetic Resonance Imaging/methods (2)
- Male (3)
- Neuronal Plasticity/physiology (1)
- Pattern Recognition, Visual/physiology (1)
- Phobic Disorders/*psychology (1)
- Photic Stimulation (2)
- Photic Stimulation/methods (1)
- Prefrontal Cortex/blood supply/physiopathology (1)
- Psychophysics (1)
- Reflex, Startle/physiology (1)
- Self Concept (1)
- Serotonin Plasma Membrane Transport Proteins/*genetics (1)
- *Sex Characteristics (1)
- Sex Characteristics (1)
- *Spiders (1)
- *Stress, Psychological/genetics/pathology/psychology (1)
- Young Adult (1)