title: Reduced neural habituation in the amygdala and social impairments in autism spectrum disorders.
abstract: OBJECTIVE
  Amygdala dysfunction has been proposed as a critical component in social impairment in autism spectrum disorders. This study was designed to investigate whether abnormal habituation characterizes amygdala dysfunction in autism spectrum disorders and whether the rate of amygdala habituation is related to social impairment.
  
  
  METHODS
  Using functional MRI, the authors measured change over time in activation of the amygdala and fusiform gyrus to neutral facial stimuli in adults with autism spectrum disorders and healthy comparison adults.
  
  
  RESULTS
  The comparison group evidenced significantly greater amygdala habituation bilaterally than the autism spectrum group. There were no group differences in overall fusiform habituation. For the autism spectrum group, lower levels of habituation of the amygdala to the face stimuli were associated with more severe social impairment.
  
  
  CONCLUSIONS
  These results suggest amygdala hyperarousal in autism spectrum disorders in response to socially relevant stimuli. Further, sustained amygdala arousal may contribute to the social deficits observed in autism spectrum disorders.
authors.affiliation: Department of Radiology, University of Washington, Box 357115, Seattle, WA 98195, USA. nkleinha@u.washington.edu
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Kleinhans
authors.forename: L Clark
authors.initials: LC
authors.lastname: Johnson
authors.forename: Todd
authors.initials: T
authors.lastname: Richards
authors.forename: Roderick
authors.initials: R
authors.lastname: Mahurin
authors.forename: Jessica
authors.initials: J
authors.lastname: Greenson
authors.forename: Geraldine
authors.initials: G
authors.lastname: Dawson
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Aylward
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000503:physiopathology*; D001143:Arousal / Q000502:physiology; D001288:Attention / Q000502:physiology; D001321:Autistic Disorder / Q000503:physiopathology*; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology; D005145:Face; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012919:Social Behavior; D055815:Young Adult