To investigate the neuroscience behind socialising, Andreas Meyer-Lindenberg and colleagues have scanned the brains of people with the genetic disorder Williams-Beuren syndrome and compared them with scans of healthy controls. People with Williams syndrome are socially fearless, impulsive, erratic, and highly empathic, but they’re excessively anxious about non-social situations.
Meyer-Lindenberg recruited 13 people with Williams syndrome who were unusual in that they had normal IQ. They and 13 healthy controls were asked to match one of two simultaneously presented faces with a different face that showed the same emotion (angry or afraid). In another task they had to match fearful or threatening scenes. A key difference emerged. The Williams syndrome patients showed increased amygdala activation during the scene task whereas the controls showed increased amygdala activation during the face task. The amygdala is an almond shaped region buried deep in the brain and known to be involved in emotions.
When the researchers investigated circuitry at the front of the brain, they found abnormal or absent regulation of the amygdala by key regions in the prefrontal cortex of the Williams syndrome participants. In particular, the orbitofrontal cortex regulated amygdale functioning in the healthy controls but not in the Williams syndrome participants. And the dorsolateral prefrontal cortex was linked to the orbitofrontal cortex in healthy controls but not in the Williams participants.
The researchers said “Together with nonhuman primate findings of increased social but decreased non-social fear after neonatal amygdala lesions, our data suggest the possibility that the opposite pattern of dissociated fear (decreased social fear and increased non-social fear) found in individuals with Williams syndrome may be a consequence of a congenital deficiency in a prefrontal system involved in inhibitory amygdala regulation”.
Meyer-Lindenberg, A., Hariri, A.R., Munoz, K.E., Mervis, C.B., Mattay, V.S., Morris, C.A. & Berman, K.F. (2005). Neural correlates of genetically abnormal social cognition in Williams syndrome. Nature Neuroscience, Advance Online Publication: DOI: 10.1038/nn1494.