Reduced neural synchronization of gamma-band MEG oscillations in first-degree relatives of children with autism.
BACKGROUND
Gamma-band oscillations recorded from human electrophysiological recordings, which may be associated with perceptual binding and neuronal connectivity, have been shown to be altered in people with autism. Transient auditory gamma-band responses, however, have not yet been investigated in autism or in the first-degree relatives of persons with the autism.


METHODS
We measured transient evoked and induced magnetic gamma-band power and inter-trial phase-locking consistency in the magnetoencephalographic recordings of 16 parents of children with autism, 11 adults with autism and 16 control participants. Source space projection was used to separate left and right hemisphere transient gamma-band measures of power and phase-locking.


RESULTS
Induced gamma-power at 40 Hz was significantly higher in the parent and autism groups than in controls, while evoked gamma-band power was reduced compared to controls. The phase-locking factor, a measure of phase consistency of neuronal responses with external stimuli, was significantly lower in the subjects with autism and the autism parent group, potentially explaining the difference between the evoked and induced power results.


CONCLUSIONS
These findings, especially in first degree relatives, suggest that gamma-band phase consistency and changes in induced versus induced power may be potentially useful endophenotypes for autism, particularly given emerging molecular mechanisms concerning the generation of gamma-band signals.
Rojas
Donald C
DC
University of Colorado at Denver and Health Sciences Center, 4200 E, 9th Avenue, Denver, CO, USA. don.rojas@uchsc.edu
Maharajh
Keeran
K
Teale
Peter
P
Rogers
Sally J
SJ
D000328:Adult; D001321:Autistic Disorder / Q000175:diagnosis* / Q000503:physiopathology* / Q000523:psychology; D001921:Brain / Q000503:physiopathology*; D002648:Child; D016241:Child of Impaired Parents / Q000706:statistics & numerical data*; D003344:Cortical Synchronization / Q000379:methods*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010290:Parents