Increased volumes of lobule VI in a valproic acid model of autism are associated with worse set-shifting performance in male Long-Evan rats.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a skewed sex-based diagnostic ratio. While males are at a higher risk for ASD, it is critical to understand the neurobiology of the disorder to develop better treatments for both males and females. Our prior work has demonstrated that VPA (valproic acid) treated offspring had impaired performance on an attentional set-shifting task. The current study used MRI and regions of interest analyses to measure the volumes of cerebellar subregions in VPA and controls rats that had participated in the attentional set-shifting task. VPA males had significantly more volume in lobule VI compared to male controls. VPA female rats had significantly less volume in lobules I, IV and X compared to female controls. In addition, it was revealed that decreases in volume for VPA females was associated with worse performance. Males with increases in lobule VI were also impaired on the set-shifting task. Similar volumetric differences within the cerebellum have been observed in humans with ASD, which suggests that the VPA model is capturing some of the same brain changes observed in humans with ASD, and that these changes in volume may be impacting cognition.