[Advances in neuroimaging research on Asperger syndrome]

Autism spectrum disorder (ASD) (i.e., autism and Asperger syndrome) is a neurodevelopmental disorder, although its etiology is still unclear. Neuroimaging studies have attempted to identify the neurobiological basis of ASD. This article reviews recent progress in ASD research using magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). MRI studies documented structural and functional abnormalities in cerebella, the frontal lobes, the temporal lobes, and limbic systems of individuals with ASD. SPECT and PET studies suggested that abnormalities of the serotonergic system, in addition to decreased regional cerebral blood flow in the frontal and temporal lobes, are implicated in the pathophysiology of ASD.