Ihre Suche

Suche zurücksetzen
In authors or contributors
Thema

Ergebnisse 3 Einträge

RelevanzNeueste zuerstÄlteste zuerstAutor A-ZAutor Z-ATitel A-ZTitel Z-A
Abstracts
  • Windmann, S., Kirsch, P., Mier, D., Stark, R., Walter, B., Güntürkün, O., & Vaitl, D. (2006). On framing effects in decision making: linking lateral versus medial orbitofrontal cortex activation to choice outcome processing. Journal of Cognitive Neuroscience, 18(7), 1198–1211. https://doi.org/10.1162/jocn.2006.18.7.1198

    Two correlates of outcome processing in the orbitofrontal cortex (OFC) have been proposed in the literature: One hypothesis suggests that the lateral/medial division relates to representation of outcome valence (negative vs. positive), and the other suggests that the medial OFC maintains steady stimulus-outcome associations, whereas the lateral OFC represents changing (unsteady) outcomes to prepare for response shifts. These two hypotheses were contrasted by comparing the original with the inverted version of the Iowa Gambling Task in an event-related functional magnetic resonance imaging experiment. Results showed (1) that (caudo) lateral OFC was indeed sensitive to the steadiness of the outcomes and not merely to outcome valence and (2) that the original and the inverted tasks, although both designed to measure sensitivity for future outcomes, were not equivalent as they enacted different behaviors and brain activation patterns. Results are interpreted in terms of Kahneman and Tversky's prospect theory suggesting that cognitions and decisions are biased differentially when probabilistic future rewards are weighed against consistent punishments relative to the opposite scenario [Kahneman, D., & Tversky, A. Choices, values, and frames. American Psychologist, 39, 341-350, 1984]. Specialized processing of unsteady rewards (involving caudolateral OFC) may have developed during evolution in support of goal-related thinking, prospective planning, and problem solving.

  • Merz, C. J., Tabbert, K., Schweckendiek, J., Klucken, T., Vaitl, D., Stark, R., & Wolf, O. T. (2010). Investigating the impact of sex and cortisol on implicit fear conditioning with fMRI. Psychoneuroendocrinology, 35(1), 33–46. https://doi.org/10.1016/j.psyneuen.2009.07.009

    Fear conditioning is influenced by stress but opposing effects in males and females have often been reported. In a previous human functional magnetic resonance imaging (fMRI) study, we observed acute effects of the stress hormone cortisol on prefrontal structures. Men showed evidence for impaired fear conditioning after cortisol treatment, while the opposite pattern was found for women. In the current experiment, we tested whether similar sex-dependent effects would occur on the neural level if contingency awareness was prevented experimentally to investigate implicit learning processes. A differential fear conditioning experiment with transcutaneous electrical stimulation as unconditioned stimulus and geometric figures as conditioned stimuli (CS) was conducted. One figure was always paired (CS+), whereas the other (CS-) was never paired with the UCS. Thirty-nine (19 female) subjects participated in this fMRI study, receiving either placebo or 30 mg cortisol (hydrocortisone) before conditioning. Dependent variables were skin conductance responses (SCRs) and neural activity (BOLD signal). In line with prior findings in unaware participants, no differential learning could be observed for the SCRs. However, a sex x cortisol interaction was detected with a reduced mean response to the CS after cortisol treatment in men, while the opposite pattern was observed in women (enhanced mean SCR under cortisol). In the contrast CS+ minus CS-, neural activity showed a sex x cortisol interaction in the insula and further trends in the hippocampus and the thalamus. In these regions, cortisol reduced the CS+/CS- differentiation in men but enhanced it in women. In contrast to these sex specific effects, differential amygdala activation was found in the placebo group but not in the cortisol group, irrespective of sex. Further, differential neural activity in the amygdala and thalamus were positively correlated with the SCRs in the placebo group only. The present study in contingency unaware participants illustrates that cortisol has in some brain regions sex specific effects on neural correlates of emotional learning. These effects might translate into a different vulnerability of the two sexes for anxiety disorders.

  • Kirsch, P., Schienle, A., Stark, R., Sammer, G., Blecker, C., Walter, B., Ott, U., Burkart, J., & Vaitl, D. (2003). Anticipation of reward in a nonaversive differential conditioning paradigm and the brain reward system: an event-related fMRI study. NeuroImage, 20(2), 1086–1095. https://doi.org/10.1016/S1053-8119(03)00381-1

    Findings from animal as well as human neuroimaging studies suggest that reward delivery is associated with the activation of subcortical limbic and prefrontal brain regions, including the thalamus, the striatum, the anterior cingulate and the prefrontal cortex. The aim of the present study was to explore if these reward-sensitive regions are also activated during the anticipation of reinforcers that vary with regard to their motivational value. A differential conditioning paradigm was performed, with the presentation of a rewarded reaction time task serving as the unconditioned stimulus (US). Depending on their reaction time, subjects were given (or not given) a monetary reward, or were presented with a verbal feedback consisting of being fast or slow. In a third control condition no task needed to be executed. Each of the three conditions was introduced by a different visual cue (CS). Brain activation of 27 subjects was recorded using event-related functional magnetic resonance imaging. The results showed significant activation of the substantia nigra, thalamic, striatal, and orbitofrontal brain regions as well as of the insula and the anterior cingulate during the presentation of a CS signalling a rewarded task. The anticipation of a monetary reward produced stronger activation in these regions than the anticipation of positive verbal feedback. The results are interpreted as reflecting the motivation-dependent reactivity of the brain reward system with highly motivating stimuli (monetary reward) leading to a stronger activation than those less motivating ones (verbal reward).

RIS

Empfohlenes Format für die meisten Literaturverwaltungsprogramme

BibTeX

Empfohlenes Format für BibTeX-fähige software

Custom feed
Last update from database: 11.08.25, 05:41 (UTC)