Behavioral and Magnetoencephalographic Correlates of Fear Generalization Are Associated with Responses to Later Virtual Reality Exposure Therapy in Spider Phobia
As overgeneralization of fear is a pathogenic marker of anxiety disorders, we investigated whether pre-treatment levels of fear generalization in spider-phobic patients are associated with their response to exposure-based treatment, in order to identify pre-treatment correlates of treatment success. Ninety patients with spider phobia completed pre-treatment clinical and magnetoencephalography (MEG) assessments, one session of virtual reality exposure therapy, and a post-treatment clinical assessment. Based on the primary outcome (30% symptom reduction in self-reported symptoms from pre- to post-treatment) they were categorized as responders or non-responders. In a pre-treatment MEG fear generalization paradigm involving fear conditioning with two unconditioned stimuli (UCS), we obtained fear ratings, UCS-expectancy ratings, and event-related fields to conditioned stimuli (CS+, CS-) and 7 different generalization stimuli (GS) on a perceptual continuum from CS+ to CS-. Prior to treatment, non-responders showed behavioral overgeneralization indicated by more linear generalization gradients in fear ratings. Analyses of MEG source estimations revealed that non-responders showed a decline of their (inhibitory) frontal activations to safety-signaling CS- and GS compared to CS+ over time, while responders maintained these activations at early (<300ms) and late processing stages. Results provide initial evidence that pre-treatment differences of behavioral and neural markers of fear generalization are associated with later responses to behavioral exposure. Findings demonstrate the relevance of inhibitory learning functions and their spatio-temporal neural reflections in this interplay. Findings stimulate research on mechanism-based augmentation strategies for behavioral therapies.