Project B4: Memories of a stressful episode
Stress is known to enhance memory consolidation through the interdependent action of the stress hormones (nor)adrenalin and cortisol. However, what exactly we remember from a stressful episode itself had not been tested in an experimental setting in humans. Studies conducted in our department have demonstrated that stressed participants remember visual items as well as an ambient odour better compared to participants undergoing a stress-free control condition. Moreover, their recognition memory relied more on hippocampal based recollection processes. Furthermore, we could show that olfactory stimuli are effective reminder cues for memories of stressful but not of non-stressful situations. These findings demonstrate that stress enhances memory consolidation and that olfactory stimuli are powerful reminder cues of stressful memories.
Our current studies try to provide a mechanistic understanding of these findings. The role of visual exploration in a stressful situation, measured with eye tracking and stress neuromodulators (cortisol and noradrenalin), is investigated. Possible distinct effects of stress and the stress hormone cortisol on recollection versus familiarity will be investigated for memory consolidation and memory retrieval using behavioural and neuroimaging techniques. The role of olfactory reminder cues will be systematically compared with visual and auditory cues using emotional and neutral stimuli.
Furthermore, effects of stress on hippocampal based perceptual processes will be tested in collaborative experiments. Previous studies demonstrated that the visual perception of spatial scenes relies on the hippocampus, while perceiving objects and faces is hippocampus-independent. Current and future studies investigate to what extent visual perception is influenced by stress and aim to reveal the underlying neural mechanisms of this influence.
Last but not least the impact of stress and stress hormones on non-hippocampal based (cortical) perceptual learning processes will be tested in collaborative experiments.
Together, these studies will lead to an enhanced mechanistic understanding of the enhancing and impairing effects of stress on the representation of sensory processes.
Our project P5 of this multidisciplinary research unit is entitled “effects of the stress hormone cortisol on extinction retrieval”. It has the goal to test the underlying neuroendocrine mechanisms of the impact of stress on extinction retrieval. Moreover its neural correlates should be explored. We therefore will test the influence of the stress hormone cortisol on extinction retrieval within a renewal paradigm using a predictive learning as well as a fear conditioning task. In order to characterize the neural correlates of the cortisol effects, functional neuroimaging will be employed during acquisition, extinction and renewal testing in both tasks. Together these studies will lead to an enhanced mechanistic understanding of the impact of stress on extinction memory retrieval.
DFG-Project: Influence of cortisol on context-dependent extinction learning
This collaborative project investigates the effect of cortisol administration as well as multiple contexts during extinction learning on electrodermal and neuronal correlates of generalization processes. The results of these studies will contribute to a better understanding of the neurobiological foundations underlying generalization of therapy success to new contexts. The project is conducted in cooperation with the Department of Psychotherapy and Systems Neuroscience (Dr. Andrea Hermann, Prof. Rudolf Stark) at the Justus Liebig University Giessen.
It is funded by the German Research Foundation (DFG, grant ME 3831/4-1).
The ability to cognitively regulate emotions is of vital importance for us humans. A deficient ability to adaptively regulate one’s (negative) emotion is regarded a major risk factor for the development of mental disorders. Acute psychological stress causes the release of stress hormones (e.g. noradrenalin and cortisol) which influence brain function. Emotionally stress is associated with an increase in negative affect and an enhanced susceptibility to distraction by emotional stimuli. The goal of the present project is the investigation of acute and delayed stress effects on the efficacy of emotion regulation using different cognitive strategies. In addition the presence of sex differences will be characterized. The results of this project will contribute to a better understanding of the impact of stress and stress hormones on emotion regulation processes.
MERCUR project: Influence of stress on the retrieval of socially relevant fear memories
This project explores the effect of in- and outgroup faces as conditioned stimuli in a differential fear conditioning design and how psychosocial stress exerts an effect on electrodermal correlates of socially modulated extinction recall. The results of this project will contribute to a better understanding of the development and maintenance of potential resentments towards outgroups and factors influencing this relationship. It is funded by the Mercator Research Center Ruhr (MERCUR).
Cortisol and stress effects on fear memory reconsolidation
When already-consolidated memories are reactivated (retrieved) they become again susceptible for modification (enhancement, impairment or update) for a limited period of time until their reconsolidation is completed. Whereas the enhancing effect of cortisol and stress on initial consolidation is well documented, the knowledge on their effects on memory reconsolidation is lacking. In this project we investigate the influence of cortisol and behavioral stress on fear memory reconsolidation in healthy men and women. This knowledge can significantly contribute to our understanding and treatment of anxiety disorders and PTSD. This project is associated with the multidisciplinary research unit “extinction learning” (FOR 1581) funded by the DFG.
Contact: Shira Meir Drexler