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"Tabbert, Katharina"

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Image Processing, Computer-Assisted

Ergebnisse 3 Einträge

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Tabbert, K., Stark, R., Kirsch, P., & Vaitl, D. (2005). Hemodynamic responses of the amygdala, the orbitofrontal cortex and the visual cortex during a fear conditioning paradigm. International Journal of Psychophysiology : Official Journal of the International Organization of Psychophysiology, 57(1), 15–23. https://doi.org/10.1016/j.ijpsycho.2005.01.007

Functional magnetic resonance imaging (fMRI) studies consistently demonstrate an enhanced activation of the visual cortex in reaction to emotionally salient visual stimuli. This increase of activation is probably modulated by top-down processes, that are initiated in emotion processing structures, specifically the amygdala and the orbitofrontal cortex. In the present fMRI study, a differential fear conditioning paradigm was applied to investigate this assumed modulation. Hemodynamic responses towards a neutral visual stimulus (CS+) predicting an electrical stimulation (UCS) were compared with responses towards a neutral and unpaired stimulus (CS-). Thereby, particularly the time courses of neural responses were considered. Skin conductance measures were concurrently recorded. Our results show that the differentiation between CS+ and CS- within the amygdala and the extended visual cortex was accomplished during a late acquisition phase. In the orbitofrontal cortex the differentiation occurred at an earlier stage and was then sustained throughout acquisition. It is suggested that these altering activation patterns are reflecting different phases of learning, integrating the analyzed regions to varying degrees. Additionally, the results indicate that statistical analyses comprising a temporal variation of hemodynamic responses are more likely to detect amygdala activation.
Tabbert, K., Merz, C. J., Klucken, T., Schweckendiek, J., Vaitl, D., Wolf, O. T., & Stark, R. (2010). Cortisol enhances neural differentiation during fear acquisition and extinction in contingency aware young women. Neurobiology of Learning and Memory, 94(3), 392–401. https://doi.org/10.1016/j.nlm.2010.08.006

Previously, we observed cortisol induced enhancement of neural fear acquisition in women. Yet, less is known about cortisol effects on neural fear extinction. Via differential fear conditioning, we explored cortisol effects on acquisition and extinction. Twenty contingency aware women taking monophasic oral contraceptives were included; 10 received placebo, 10 cortisol before conditioning. Group differences emerged in anterior cingulate cortex (ACC), hippocampus, and--as trend--in insula and thalamus during acquisition and in hippocampus, thalamus, and--as trend--in amygdala, insula, and ACC during extinction. During acquisition group differences were due to higher responses to the CS+ than to the CS- in the cortisol group. Notably, during extinction, group differences were due to higher responses to the CS- than to the CS+ in this group. Thus, cortisol induced a fear acquisition and extinction specific enhanced neural differentiation.
Tabbert, K., Merz, C. J., Klucken, T., Schweckendiek, J., Vaitl, D., Wolf, O. T., & Stark, R. (2011). Influence of contingency awareness on neural, electrodermal and evaluative responses during fear conditioning. Social Cognitive and Affective Neuroscience, 6(4), 495–506. https://doi.org/10.1093/scan/nsq070

In an fMRI study, effects of contingency awareness on conditioned responses were assessed in three groups comprising 118 subjects. A differential fear-conditioning paradigm with visual conditioned stimuli, an electrical unconditioned stimulus and two distractors was applied. The instructed aware group was informed about the contingencies, whereas the distractors prevented contingency detection in the unaware group. The third group (learned aware) was not informed about the contingencies, but learned them despite the distractors. Main effects of contingency awareness on conditioned responses emerged in several brain structures. Post hoc tests revealed differential dorsal anterior cingulate, insula and ventral striatum responses in aware conditioning only, whereas the amygdala was activated independent of contingency awareness. Differential responses of the hippocampus were specifically observed in learned aware subjects, indicating a role in the development of contingency awareness. The orbitofrontal cortex showed varying response patterns: lateral structures showed higher responses in instructed aware than unaware subjects, the opposite was true for medial parts. Conditioned subjective and electrodermal responses emerged only in the two aware groups. These results confirm the independence of conditioned amygdala responses from contingency awareness and indicate specific neural circuits for different aspects of fear acquisition in unaware, learned aware and instructed aware subjects.

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

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