A Brain Circuit for Bungee Jumping?

Are you nuts for all things newfangled? Or do you stick with the tried and true? New research hints at how such personality traits may be wired into our brains.

Scientists have known for some time that the white matter in our brains--the strands of nerve fibers that connect nerve cell bodies, or gray matter--serve as the wires through which neural information flows. However, figuring out exactly which parts of the brain connect to each other, and how strong these connections are, has only been possible recently in living humans thanks to a technique called diffusion tensor imaging. A type of magnetic resonance imaging, the method traces the web of white matter by following the diffusion of fluid through the nerve fibers. Neurologists have used this technology in clinical studies to evaluate brain damage. Neurologist Bernd Weber of the University of Bonn in Germany, former Bonn psychologist Michael Cohen, and colleagues decided to take the tool in a new direction: "No one had really investigated [white matter's] connection to personality," says Weber.

To do this, the team asked a group of 20 volunteers to complete a survey to assess whether they were novelty seekers or comfort seekers. The volunteers answered true-or-false questions such as, "I like to try new things just for fun," or "I'd rather stay home than go out." The team then analyzed the volunteers' brains using diffusion tensor imaging, which revealed striking differences between the two groups: Novelty seekers sported a robust bundle of white matter linking the hippocampus, which forms memories and distinguishes between new and old experiences, to a region of the brain known as the ventral striatum, a major planning and reward center. In comfort seekers, on the other hand, the ventral striatum was more strongly connected to the frontal lobe, which plays a role in following social norms (among many other functions), the team reports online this week in Nature Neuroscience.

Other researchers are bullish on the work. "It's rare to find a structural correlation to such high cognitive behavior," says Tim Behrens, a psychologist at Oxford University in the U.K. "It's quite impressive." Turhan Canli, a psychologist with Stony Brook University in Stony Brook, New York, agrees. "There really aren't very many studies looking at the differences in white matter connectivity between individuals, ... which makes [the finding] quite valuable," Canli says. "When you look at the data, the association they see is quite striking."