title: Cerebral blood flow during anticipation of public speaking in social phobia: a PET study.
abstract: BACKGROUND
  The aim was to examine the neural correlates of anxiety elicited by the anticipation of public speaking in individuals with social phobia. Positron emission tomography and (15)O-water was used to measure regional cerebral blood flow in subjects with DSM-IV defined social phobia during anxiety anticipation. Heart rate and subjective anxiety were also recorded. While being scanned, subjects were speaking alone either before or after speaking in public. To evaluate anticipatory anxiety we compared individuals speaking alone before they were speaking in front of an audience with those who did the reverse.
  
  
  RESULTS
  Heart rate and subjective anxiety measures confirmed anticipatory anxiety in social phobics who performed their private speech before their public. This was accompanied by enhanced cerebral blood flow in the right dorsolateral prefrontal cortex, left inferior temporal cortex, and in the left amygdaloid-hippocampal region. Brain blood flow was lower in the left temporal pole and bilaterally in the cerebellum in the anticipation group.
  
  
  CONCLUSIONS
  Brain regions with altered perfusion presumably reflect changes in neural activity associated with worry about anticipated public performance. We speculate that anticipatory anxiety in social phobics originates in an affect sensitive fear network encompassing the amygdaloid-hippocampal region, prefrontal, and temporal areas.
authors.affiliation: Department of Social Sciences, Orebro University, Orebro, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Tillfors
authors.forename: Tomas
authors.initials: T
authors.lastname: Furmark
authors.forename: Ina
authors.initials: I
authors.lastname: Marteinsdottir
authors.forename: Mats
authors.initials: M
authors.lastname: Fredrikson
mesh_terms: D000328:Adult; D001007:Anxiety / Q000000981:diagnostic imaging / Q000503:physiopathology; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010698:Phobic Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012039:Regional Blood Flow; D013060:Speech / Q000502:physiology*; D013315:Stress, Psychological / Q000000981:diagnostic imaging / Q000503:physiopathology; D014055:Tomography, Emission-Computed