"They studied 13 people with Williams syndrome and 23 controls, only a subset of whom participated in each of the various imaging modalities.
It’s only recently that newer techniques, such as DTI and functional connectivity, which infers connectivity based on correlated activity of different brain regions, have become reliable enough to be used more widely, says Paul Thompson, professor of neurology at the University of California, Los Angeles, who was not involved in the study.
The study is unique not only in its target and combination of imaging technologies, but in the population under study. Berman’s team chose to focus only on individuals who have Williams syndrome and a normal IQ, a relatively small percentage of people with this rare disorder, to eliminate the possible effects of IQ.
Individuals with Williams syndrome have differences in brain structure, connectivity and function compared with controls, the study found. Specifically, the researchers found that the gray matter of the dorsal anterior insula, a region associated with integrating emotions and cognition, is smaller in people with the disorder, while the ventral anterior insula, an area implicated in social and emotional processes, is larger.
Functional measures corroborated these results. Blood flow is reduced in the dorsal anterior insula and increased in the ventral anterior insula.
The white-matter tract that connects the anterior insula to the amygdala and orbitofrontal cortex, known as the uncinate fasciculus, is more disorganized in people with Williams syndrome. And activity in the anterior insula is less well correlated with activity in the orbitofrontal cortex, amygdala and anterior cingulate cortex.
Perhaps most significant, the degree of alteration is linked to the magnitude of the individual’s Williams syndrome personality, as measured by a personality test.
The link between personality traits and the insula is specific: Researchers did not find a similar correlation with the hippocampus, part of the brain involved in learning and memory. And verbal IQ, which is unrelated to personality, was not linked to changes in the insula.
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