Speech Stimulation during Functional MR Imaging as a Potential Indicator of Autism 1

Materials and Methods: This prospective study was approved by the institutional review board, and informed consent was obtained from the parents or guardians of all subjects. Functional MR imaging was performed during passive presentations of prerecorded speech in 15 control subjects (mean age 6 standard deviation, 12.1 years 6 4.3) and 12 languageimpaired, age-matched autistic subjects (mean age, 12.4 years 6 4.7). An additional 27 autistic children (mean age, 8.4 years 6 3.1), who underwent imaging while sedated with propofol as part of routine clinical MR evaluations, were also included. Activation maps for each subject were computed by using univariate general linear model analyses. The spread (quantifi ed as number of voxels) and amplitude of the functional MR imaging activation were then quantifi ed within two anatomically specifi ed regions of interest known to be involved with language: the primary auditory cortex (A1) and the superior temporal gyrus (STG). Group differences were compared by using analysis of variance, two-sample t tests, and Wilcoxon rank sum tests where appropriate. The threshold for autism was defi ned as 1 standard deviation below the control mean for subjects imaged in the alert state . A similar threshold was estimated for sedated autistic subjects on the basis of differences between nonsedated and sedated autistic subjects.