Previous imaging studies by the NIMH researchers found abnormal tracts of the neuronal fibers that conduct long-distance communications between brain regions -- likely resulting from neurons migrating to the wrong destinations during early development.
Evidence suggests that genes influence our temperament and the development of mental disorders via effects on brain circuits that regulate behavior. Yet direct demonstration of this in humans has proven elusive. Since the genetic basis of Williams syndrome is well known, it offers a unique opportunity to explore such effects with neuroimaging, reasoned the researchers.
Although the insula had not previously been studied in such detail in the disorder, it was known to be related to brain circuitry and certain behaviors, such as empathy, which is also highly prominent in the disorder. Berman and colleagues hypothesized that the insula's anatomy, function and connectivity would predict patients' scores for Williams syndrome-associated traits on personality rating scales. Fourteen intellectually normal Williams syndrome participants and 23 healthy controls participated in the study.
Magnetic resonance imaging (MRI) revealed that patients had decreased gray matter the brain's working tissue in the bottom front of the insula, which integrates mood and thinking. By contrast, they had increased gray matter in the top front part of the insula, which has been linked to social/emotional processes.
Diffusion tensor imaging, which by detecting the flow of water in nerve fibers can identify and measure the connections between brain areas, showed reduced white matter the brain's long-distance wiring between thinking and emotion hubs.
Tracking radioactively-tagged water in order to measure brain blood flow at rest, via positron emission tomography (PET), exposed activity aberrations consistent with the MRI abnormalities. The PET scans also reveale
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NIH/National Institute of Mental Health