title: MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism.
abstract: Motivated by auditory and speech deficits in autism spectrum disorders (ASD), the frequency dependence of superior temporal gyrus (STG) 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in children with ASD and typically developing controls were evaluated. Whole-cortex magnetoencephalography (MEG) was obtained from 17 typically developing children and 25 children with ASD. Subjects were presented tones with frequencies of 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 STG activity was examined. No M50 latency or amplitude Group differences were observed. In the right hemisphere, a Group x Frequency ANOVA on M100 latency produced a main effect for Group (P=0.01), with an average M100 latency delay of 11 msec in children with ASD. In addition, only in the control group was the expected association of earlier M100 latencies in older than younger children observed. Group latency differences remained significant when hierarchical regression analyses partialed out M100 variance associated with age, IQ, and language ability (all P-values <0.05). Examining the right-hemisphere 500 Hz condition (where the largest latency differences were observed), a sensitivity of 75%, a specificity of 81%, and a positive predictive value (PPV) of 86% was obtained at a threshold of 116 msec. The M100 latency delay indicates disruption of encoding simple sensory information. Given similar findings in language impaired and non-language impaired ASD subjects, a right-hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism.
authors.affiliation: Department of Radiology, The Children's Hospital of Philadelphia, 34th St. and Civic Center Blvd., Philadelphia, PA 19104, USA. robertstim@email.chop.edu
authors.forename: Timothy P L
authors.initials: TP
authors.lastname: Roberts
authors.forename: Sarah Y
authors.initials: SY
authors.lastname: Khan
authors.forename: Mike
authors.initials: M
authors.lastname: Rey
authors.forename: Justin F
authors.initials: JF
authors.lastname: Monroe
authors.forename: Katelyn
authors.initials: K
authors.lastname: Cannon
authors.forename: Lisa
authors.initials: L
authors.lastname: Blaskey
authors.forename: Sarah
authors.initials: S
authors.lastname: Woldoff
authors.forename: Saba
authors.initials: S
authors.lastname: Qasmieh
authors.forename: Mike
authors.initials: M
authors.lastname: Gandal
authors.forename: Gwen L
authors.initials: GL
authors.lastname: Schmidt
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Zarnow
authors.forename: Susan E
authors.initials: SE
authors.lastname: Levy
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Edgar
mesh_terms: D000161:Acoustic Stimulation; D000367:Age Factors; D016477:Artifacts; D001303:Auditory Cortex / Q000503:physiopathology; D015415:Biomarkers; D001931:Brain Mapping; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology; D004569:Electroencephalography; D004585:Electrooculography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology; D007805:Language Development Disorders / Q000175:diagnosis / Q000503:physiopathology; D015225:Magnetoencephalography; D008297:Male; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted
chemical_list: D015415:Biomarkers