title: Dissociation of neural responses and skin conductance reactions during fear conditioning with and without awareness of stimulus contingencies.
abstract: This study investigates the effect of awareness of stimulus contingencies on BOLD responses within the amygdala, the orbitofrontal, and the occipital cortex, and on differential skin conductance responses (SCRs) during fear conditioning. Of two geometric figures, the paired conditioned stimulus (CS+) predicted an electrical stimulus (unconditioned stimulus = UCS), whereas the unpaired conditioned stimulus (CS-) was not followed by the UCS. Awareness of stimulus contingencies was manipulated experimentally, creating an aware and an unaware group: a distracter figure and a working memory task were introduced to conceal the stimulus contingencies of the conditioning paradigm, hence preventing contingency detection in the unaware group. The aware group was informed beforehand about the relation between CS+, CS-, and UCS. Differential SCRs were only obtained in the aware but not in the unaware group. Conversely, we observed enhanced responses of the amygdala, the orbitofrontal, and the occipital cortex to the CS+ in the unaware group only. Thus, we found a dissociation of SCR differentiation and the activation of a neural fear network depending on the presence or absence of awareness. These results support a model of fear conditioning that distinguishes between a more cognitive level of learning, reflected in contingency awareness and differential SCRs, and the awareness independent activation of a fear network.
authors.affiliation: Bender Institute of Neuroimaging, University of Giessen, Otto-Behaghel-Strasse 10 H, 35394, Germany. katharina.e.tabbert@psychol.uni-giessen.de
authors.forename: Katharina
authors.initials: K
authors.lastname: Tabbert
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stark
authors.forename: Peter
authors.initials: P
authors.lastname: Kirsch
authors.forename: Dieter
authors.initials: D
authors.lastname: Vaitl
mesh_terms: D000328:Adult; D000679:Amygdala / Q000502:physiology; D001143:Arousal / Q000502:physiology; D001245:Association Learning / Q000502:physiology*; D001364:Awareness / Q000502:physiology*; D001931:Brain Mapping; D002531:Cerebellum / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007721:Knowledge of Results, Psychological; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology