Fig. 1. Proton magnetic resonance spectroscopy (¹H-MRS) data acquisition in adults with autism spectrum disorder (ASD) and typically developing (TD) controls.

Location of ¹H-MRS voxel placement at the (a) bilateral thalami and (b) left DLPFC. Improved MEGA-SPECIAL spectra and corresponding edited spectra are shown for the (c) thalami and (d) left DLPFC. Group-mean GABA/Water concentrations by diagnosis and gender are shown for the (e) bilateral thalami and (f) left DLPFC. Error bars represent ± 1 SEM. Significant main effects of diagnosis or gender (P < 0.05 in primary two-way ANOVAs) are starred (*). After covarying for age, psychotropic medication usage, and IQ, the gender difference in thalamic GABA remained significant. The TD vs. ASD difference in DLPFC GABA remained significant after covarying for medication usage and IQ, but not after adjusting for age.