Ihre Suche

Suche zurücksetzen

In authors or contributors

"Kirsch, Peter"

Thema

Double-Blind Method

Ergebnisse 2 Einträge

Abstracts

Kirsch, P., Reuter, M., Mier, D., Lonsdorf, T., Stark, R., Gallhofer, B., Vaitl, D., & Hennig, J. (2006). Imaging gene-substance interactions: the effect of the DRD2 TaqIA polymorphism and the dopamine agonist bromocriptine on the brain activation during the anticipation of reward. Neuroscience Letters, 405(3), 196–201. https://doi.org/10.1016/j.neulet.2006.07.030

Dopamine is known as the main neurotransmitter modulating the activation of the reward system of the brain. The DRD2 TaqIA polymorphism is associated with dopamine D2 receptor density which plays an important role in the context of reward. Persons carrying an A1 allele have a lower D2 receptor density and a higher risk to show substance abuse. The present study was designed to investigate the influence of the DRD2 TaqIA polymorphism and the selective D2 receptor agonist bromociptine on the activation of the reward system by means of functional magnetic resonance imaging (fMRI). In a double-blind crossover study with 24 participants we found an increase of reward system activation from placebo to bromocriptine only in subjects carrying the A1 allele. Furthermore, only A1 carrier showed an increase of performance under bromocriptine. The results are interpreted as reflecting a specific sensitivity for dopamine agonists in persons carrying an A1 allele and may complement actual data and theories of the development of addiction disorders postulating a higher genetic risk for substance abuse in carrier of the A1 allele.
Stark, R., Wolf, O. T., Tabbert, K., Kagerer, S., Zimmermann, M., Kirsch, P., Schienle, A., & Vaitl, D. (2006). Influence of the stress hormone cortisol on fear conditioning in humans: evidence for sex differences in the response of the prefrontal cortex. NeuroImage, 32(3), 1290–1298. https://doi.org/10.1016/j.neuroimage.2006.05.046

The stress hormone cortisol is known to influence declarative memory and associative learning. In animals, stress has often been reported to have opposing effects on memory and learning in males and females. In humans, the effects of cortisol have mainly been studied at the behavioral level. The aim of the present experiment was to characterize the effects of a single cortisol dose (30 mg) on the hemodynamic correlates of fear conditioning. In a double-blind group comparison study subjects (17 females and 17 males) received 30 mg cortisol or placebo orally before participating in a discriminative fear conditioning paradigm. Results revealed that cortisol impaired electrodermal signs of learning (the first interval response) in males, while no conditioned SCRs emerged for the females independent of treatment. fMRI results showed that cortisol reduced activity for the CS+ > CS- comparison in the anterior cingulate, the lateral orbitofrontal cortex and the medial prefrontal cortex in males. Opposite findings (increase in these regions under cortisol) were detected in females. In addition, cortisol reduced the habituation in the CS+ > CS- contrast in the dorsolateral prefrontal cortex independent of sex. Finally, cortisol also modified the response to the electric shock (the UCS) by enhancing the activity of the anterior as well as the posterior cingulate. In sum, these findings demonstrate that in humans cortisol mostly influences prefrontal brain activation during fear conditioning and that these effects appear to be modulated by sex.

Custom feed

Last update from database: 04.06.25, 15:35 (UTC)

Ihre Suche

Ergebnisse 2 Einträge

Erkunden

Team

Eintragsart

Sprache

Thema