Functional Neuroimaging Findings in ASD(Autism Spectrum Disorders)

Functional Neuroimaging Findings in ASD

Haznedar and colleagues (1997) found reductions in portions of the right anterior cingulate during a word list learning task, and Schifter (1994) found hypometabolism in many brain re-gions during a resting state PET scan of autistic children with both mental retardation and seizure disorders. Chugani and col-leagues (1996) conducted PET scans on patients with infantile spasms, and found that 10 of 14 children that had bitemporal hypometabolism met criteria for ASD at a later follow-up. Us-ing PET and functional magnetic resonance imaging, Muller and colleagues (1998) showed that a small group of high functioning ASD adults had reversal of the usual left hemisphere dominance when listening to sentences.

Chugani and colleagues (1997) scanned autistic children utilizing an analog of tryptophan to act as a tracer in order to look at serotonin synthesis in the brain. She found asymmetries in serotonin synthesis in many of the autistic subjects. She also found that the global cerebral serotonin synthesis capac-ity of ASD children tended to increase with age (versus control subjects that show a steady decrease with age towards adult lev-els). Similar methods using a tracer to look at dopamine storage and metabolism have revealed that accumulation of this tracer was significantly reduced in the anterior medial prefrontal cortex compared with controls.