Connecting the dots between genes and human behavior
Establishing links between genes, the brain and human behavior is a central issue in cognitive neuroscience research, but studying how genes influence cognitive abilities and behavior as the brain develops from childhood to adulthood has proven difficult. Recently, by studying individuals with a rare disorder known as Williams syndrome, an international team of scientists made inroads to understanding how genes influence brain structure and cognitive abilities and how neural circuits produce language.
Williams syndrome is caused by the deletion of one of the two usual copies of approximately 25 genes from chromosome 7, resulting in mental impairment; nearly everyone with the condition is missing these same genes. The condition affects approximately 1 in 10,000 people around the world, including an estimated 20,000 to 30,000 in the United States.
Although those with Williams experience developmental delays and learning disabilities, they are exceptionally sociable and possess remarkable verbal and facial recognition abilities. Ursula Bellugi, professor and director of Salk's Laboratory for Cognitive Neuroscience, has spent much of her career studying those with Williams syndrome and was integrally involved in the recent project, which was led by Debra Mills of Bangor University in Wales; Julie Korenberg, a University of Utah professor and an adjunct professor at Salk, led the genetics aspects of the study.
Using highly sensitive sensors to measure brain activity, the researchers presented study participants with both visual and auditory stimuli in the form of unfamiliar faces and spoken sentences. They charted the small changes in voltage generated by the areas of the brain responding to these stimuli. While it had previously been believed that in individuals with Williams, the ventral portion of the brain operated normally, the team discovered that this area of the brain also processed information differently than it did in those without the syndrome and did so throughout development, from childhood to adulthood. This suggests that the brain was compensating in order to analyze information, exhibiting plasticity. The team also showed that Williams is due not to a single gene but to distinct subsets of genes, hinting that the syndrome is more complex than originally thought.
The results of this study, which was published in Developmental Neuropsychology, not only advance science's understanding of the links between genes, the brain and behavior, but may lead to new insight into such disorders as autism, Down syndrome and schizophrenia.