As any parent will tell you, no two children behave in exactly the same way. It is part of what makes each individual unique. So, why do some adolescents take more risks than others? University of Delaware (UD) Biomedical Engineer Curtis Johnson and graduate student Grace McIlvain think they may have an idea.
The part of the brain that makes adolescents want to take risks is called the socioemotional system. The brain’s cognitive control center, meanwhile, is what helps prevent adolescents from acting on these impulses.
In a recently published paper in NeuroImage, Johnson and McIlvain suggest that these two centers in the brain physically mature at different rates and that adolescents with large differences in the rate of development between these two brain regions are more likely to be risk-takers. Further, the research team theorizes that it is the brain’s fundamental structure that drives these risk-taking and control tendencies.
What makes this study unique is that the UD researchers and their collaborators used a technique called MR elastography (MRE) to safely measure the mechanical properties of the brain tissue as a measure of brain development, rather than activation of those two regions.
Elastography is a method of imaging mechanical properties of tissues using an MRI machine. Simply put, the researchers take snapshots of how the brain deforms—or bends—as it is vibrated under low frequencies, and then put those images through a specific algorithm to reverse engineer what is happening. Johnson explained that MRE vibration is safe for all ages and provides less movement than naturally occurs in the brain. It also offers less vibration than other devices designed for children, such as vibrating rockers.
Johnson likened the process to any other material testing and said the research team’s knowledge of how tissue deforms helps them interpret what is happening under different vibrations. In adults, MRE techniques have become popular for studying diseases, such as Alzheimer’s, with research showing relationships between memory and cognitive performance.
“MRE techniques do not replace other aspects of studying brain development, but they may provide a more sensitive, objective way to look at the brain’s wiring,” says Johnson, an assistant professor in the department of biomedical engineering.
Mapping Adolescent Brain Development
This is not the first time that researchers have looked at how two brain regions interact to form a certain output. But most of this work has been done using functional MRI (fMRI), where study participants are placed in the scanner and given a real-time task, and the researchers watch which areas of the brain light up to determine what areas of the brain relate to that task.
Johnson’s research group was an early pioneer in using MRE techniques to make high-resolution three-dimensional maps that enable scientists to look at specific regions of the brain. The intensity of every 3D pixel in an image has meaning. For example, bright colors indicate high stiffness, which, in this case, indicates a measure of developmental maturity.
Looking at these features of the brain in their work, the researchers found that it wasn’t the socioemotional or the cognitive control center alone, but the combination of the two centers of the brain working together at a specific age or point in time that was the definitive factor in risk taking.