Reduced neural habituation in the amygdala and social impairments in autism spectrum disorders.
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.
Kleinhans
Natalia M
NM
Department of Radiology, University of Washington, Box 357115, Seattle, WA 98195, USA. nkleinha@u.washington.edu
Johnson
L Clark
LC
Richards
Todd
T
Mahurin
Roderick
R
Greenson
Jessica
J
Dawson
Geraldine
G
Aylward
Elizabeth
E
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