title: Neural substrates of defensive reactivity in two subtypes of specific phobia.
abstract: Depending on threat proximity, different defensive behaviours are mediated by a descending neural network involving forebrain (distal threat) vs midbrain areas (proximal threat). Compared to healthy subjects, it can be assumed that phobics are characterized by shortened defensive distances on a behavioural and neural level. This study aimed at characterizing defensive reactivity in two subtypes of specific phobia [snake (SP) and dental phobics (DP)]. Using functional magnetic resonance imaging (fMRI), n = 39 subjects (13 healthy controls, HC; 13 SP; 13 DP) underwent an event-related fMRI task employing an anticipation (5-10 s) and immediate perception phase (phobic pictures and matched neutral stimuli; 1250 ms) to modulate defensive distance. Although no differential brain activity in any comparisons was observed in DP, areas associated with defensive behaviours (e.g. amygdala, hippocampus, midbrain) were activated in SP. Decreasing defensive distance in SP was characterized by a shift to midbrain activity. Present findings substantiate differences between phobia types in their physiological and neural organization that can be expanded to early stages of defensive behaviours. Findings may contribute to a better understanding of the dynamic organization of defensive reactivity in different types of phobic fear.
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany Ulrike.Lueken@tu-dresden.de.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Lueken
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Hilbert
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany.
authors.forename: Veronika
authors.initials: V
authors.lastname: Stolyar
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany.
authors.forename: Nina I
authors.initials: NI
authors.lastname: Maslowski
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Beesdo-Baum
authors.affiliation: Institute of Clinical Psychology and Psychotherapy and Neuroimaging Center, Technische Universität Dresden, D-01187 Dresden, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Wittchen
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001143:Arousal; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D003674:Defense Mechanisms; D005260:Female; D005712:Galvanic Skin Response; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010698:Phobic Disorders / Q000145:classification / Q000473:pathology* / Q000523:psychology*; D010775:Photic Stimulation; D011930:Reaction Time; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: amygdala; defensive behaviour; fMRI; midbrain; specific phobia