Search

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.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.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.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.

Objective: Down’s syndrome is associated with structural brain abnormalities and language deficits. The aim of this study was to investigate whether the superior temporal gyrus and the planum temporale, both parts of the anatomic substrate for language, are abnormal in Down’s syndrome. Method: The authors examined volumetric magnetic resonance imaging (MRI) measures of the superior temporal gyrus and the planum temporale for 17 community-dwelling patients with Down’s syndrome and 17 matched healthy comparison subjects. For the subjects with Down’s syndrome, the correlations of the superior temporal gyrus and planum temporale volumes with performance on tests of language function were examined. Results: The planum temporale volume of the patients with Down’s syndrome was smaller than that of the healthy subjects, even after differences in whole brain volume were controlled for. The volume of the superior temporal gyrus in the Down’s syndrome patients was proportionally similar to that of the comparison group. For the subjects with Down’s syndrome, neither superior temporal gyrus nor planum temporale volume was significantly correlated with performance on language tests after total brain volume was controlled for. Conclusions: In Down’s syndrome, planum temporale volume may be selectively smaller than normal, although the effect of this volume deficit on language is not clear. (Am J Psychiatry 1997; 154:1424‐1429)

Objective: Since previous work indicated smaller than normal temporal lobe structures in schizophrenic patients, the authors tested the hypothesis that this abnormality might be refiected in abnormally large sylvian fissures. Method: The subjects were 48 schizophrenic patients and 51 normal comparison subjects matched groupwise with regard to age and sex. CSF spaces (sylvian fissures, temporal lobe sulci, temporal horns, third ventricle, lateral ventricles, and superficial cerebral sulci) were visually assessed with the magnetic resonance imaging rating protocol ofthe Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Results: The sylvian fissures of the schizophrenic patients were found to be bilaterally wider than those of the comparison subjects. There were no other significant differences. Conclusigns: Schizophrenic patients appear to have larger than normal sylvian fissures, which may reflect smaller superior temporal gyri. (Am J Psychiatry 1992; 149:1195-1198)