title: Reduced functional connectivity in visual evoked potentials in children with autism spectrum disorder.
abstract: OBJECTIVE
  An analysis of EEG synchrony between homologous early visual areas tested the hypothesis that interhemispheric functional connectivity during visual stimulation is reduced in children with autism compared to controls.
  
  
  METHODS
  EEG power and coherence within and between two homologous regions of the occipital cortex were measured during long latency flash visual evoked potentials. Measures were compared between two groups of children (5.5-8.5years), one with autism spectrum disorders and the other with typical development.
  
  
  RESULTS
  In and below the theta band, interhemispheric synchrony was reduced in autistic subjects compared to typical controls by as much as 50%. Above the theta band interhemispheric synchrony in autistic children became indistinguishable from what would occur for uncorrelated cortical activity. Interhemispheric synchrony in autistic subjects was decreased in spite of bilaterally increased power. Wavelet power showed autistic children had a more rapid initial response to stimulation, a slower recovery, and more modulation at longer latencies.
  
  
  CONCLUSIONS
  Results suggest that the sensory cortices of autistic children are hypersensitive to stimulation with concurrent diminished functional connectivity between hemispheres.
  
  
  CONCLUSIONS
  Simultaneously increased intrahemispheric power and decreased interhemispheric synchronization of elementalvisual information suggests either that power increases cause poor interhemispheric connectivity or that processes, such as thalamocortical regulation, impact power and coherence independently.
authors.affiliation: Department of Pediatrics, Columbia University, New York, NY 10032, USA. jri2101@columbia.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Isler
authors.forename: K M
authors.initials: KM
authors.lastname: Martien
authors.forename: P G
authors.initials: PG
authors.lastname: Grieve
authors.forename: R I
authors.initials: RI
authors.lastname: Stark
authors.forename: M R
authors.initials: MR
authors.lastname: Herbert
mesh_terms: D001931:Brain Mapping; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000473:pathology / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology