Three dimensional reconstructions of the superior olivary complex from children with autism spectrum disorder.

Auditory dysfunction is a common symptom of autism spectrum disorder (ASD) and ranges from decreased acuity to hypersensitivity where routine sounds may result in panic or anxiety. Irrespective of altered sensitivity, there is often additional difficulty of listening in background noise. Previous studies of post-mortem brain specimens from subjects with ASD have revealed consistent dysmorphology in the superior olivary complex (SOC). The medial superior olive (MSO) is the largest and most prominent nucleus in the human SOC. Our morphological studies have shown that in subjects with ASD, there are significantly fewer neurons in the MSO and surviving neurons are smaller, more round and have abnormal dendritic orientations. Based on these findings, we hypothesize that the SOC in subjects with ASD not only includes fewer neurons but that these nuclei occupy significantly less brain volume and demonstrate abnormal nuclear contours. We investigated this hypothesis by making 3D volume renderings of the SOC nuclei using Amira software. Subjects in this study include three neurotypical and seven age-matched (ages 2-11 years of age) children with ASD. Our 3D reconstructions and volume measurements of the SOC nuclei emphasize the drastic alterations in the size, volume and organization of the human SOC in ASD.