Altered cerebellar feedback projections in Asperger syndrome

Area of Science:

• Neuroscience
• Neuroimaging
• Autism Research

Background:

• Autism spectrum disorder (ASD) is a neurodevelopmental condition.
• Cerebellar 'disconnection' is a proposed, yet unproven, biological basis for ASD.
• In vivo evidence for cerebellar involvement in Asperger syndrome is limited.

Purpose of the Study:

• To investigate the microstructural integrity of cerebellar white matter in adults with Asperger syndrome.
• To explore the relationship between cerebellar white matter abnormalities and social impairment severity.

Main Methods:

• Diffusion tensor magnetic resonance tractography was used to study cerebellar white matter.
• Measurements of mean diffusivity and fractional anisotropy were performed on 15 adults with Asperger syndrome and 16 healthy controls.
• Tract-specific analyses focused on cerebellar peduncles (input and output) and short intracerebellar fibers.

Main Results:

• No significant group differences in mean diffusivity were found.
• Adults with Asperger syndrome exhibited significantly lower fractional anisotropy in short intracerebellar fibers and the right superior cerebellar peduncle.
• Fractional anisotropy in the left superior cerebellar peduncle negatively correlated with the severity of social impairment.

Conclusions:

• Findings suggest specific cerebellar neural pathway vulnerabilities in Asperger syndrome.
• Abnormalities in the cerebellar outflow pathway may impair necessary feedback to the cerebral cortex.
• This disruption could hinder the development of adaptive social behaviors.