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Current models of attention describe attention not as a homogenous entity but as a set of neural networks whose measurement yields a set of three endophenotypes-alerting, orienting, and executive control. Previous findings revealed different neuroanatomical regions for these subsystems, and data from twin studies indicate differences in their heritability. The present study investigated the molecular genetic basis of attention in a sample of 100 healthy subjects. Attention performance was assessed with the attention network test that distinguishes alerting, orienting, and executive control (conflict) using a simple reaction time paradigm with different cues and congruent and incongruent flankers. Two gene loci on candidate genes for cognitive functioning, the functional catechol-O-methyltransferase (COMT) VAL158MET and the tryptophan hydroxylase 2 (TPH2) -703 G/T promoter polymorphism, were tested for possible associations with attention. COMT is involved in the catabolism of dopamine, and TPH is the rate-limiting enzyme for serotonin synthesis. Results showed no effect of the COMT polymorphism on attention performance. However, the TT genotype of TPH2 -03 G/T was significantly associated with more errors (a possible indicator of impaired impulse control; p = .001) and with decreased performance in executive control (p = .001). This single-nucleotide polymorphism on the TPH2 gene explained more than 10% of the variance in both indicators of attention stressing the role of the serotonergic system for cognitive functions.
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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.
Erkunden
Eintragsart
Sprache
- Englisch (2)
Thema
- Sex Characteristics
- Adult (2)
- Attention/*physiology (1)
- Brain/physiology (1)
- Catechol O-Methyltransferase/genetics (1)
- DNA Primers (1)
- Emotions/*physiology (1)
- Fear/*physiology (1)
- Female (2)
- Fixation, Ocular (1)
- Genotype (1)
- Hemodynamics/*physiology (1)
- Humans (2)
- Image Processing, Computer-Assisted (1)
- Intelligence/*genetics (1)
- Magnetic Resonance Imaging (1)
- Male (2)
- Nerve Net/physiology (1)
- Oxygen/blood (1)
- Photic Stimulation (1)
- Polymorphism, Single Nucleotide/genetics (1)
- Promoter Regions, Genetic/genetics (1)
- Psychomotor Performance/*physiology (1)
- Reaction Time/physiology (1)
- Reverse Transcriptase Polymerase Chain Reaction (1)
- Tryptophan Hydroxylase/*genetics (1)