Adolescence… we’ve all lived through this period characterized by profound physical, emotional, and cognitive changes… a period that’s also marked by a great potential for neuroplasticity. To shine greater light on brain development during this period, researchers at the University of Oslo (Norway) studied fMRI data from more than 700 people. Read on to discover the changes that take place in a teenager’s brain.

To characterize age-related differences in functional connectivity in the adolescent brain, Norwegian researchers studied fMRI data recorded during a state of rest and during a cognitive task designed to solicit working memory. The data came from a previous large-scale study conducted in 2014 by Sattherwaite and colleagues on children and adolescents in Philadelphia. The cohort was composed of 754 individuals ages 8 to 22 (405 men, 349 women, average age = 15 years). Using this data and formerly created models of adolescent brain development, Knut Kolskår, Lars Westlye and colleagues wanted to verify the following three hypotheses:

1) During this period, executive networks (such as the frontoparietal and cingulo-opercular networks) become more centralized, while the centrality of default mode network nodes decreases. This refers to a network of brain regions that are spontaneously activated when we are not engaged in a goal-directed cognitive activity, that is to say when our brain is at rest but active.

2) These changes in centrality are associated with working memory performance.

3) The centrality of key nodes shows a prolonged maturation during the studied age range (8 to 22 years).

The participants carried out a cognitive task known as the “N-back,” which involves three levels of working memory load. At the first level, the participants had to press a button each time a fractal target (visual form such as a curve or a surface) was presented to them on a screen. At the higher levels, they had to press the button each time they saw a fractal they believed to be identical to those presented one or two trials back.

The results of the study, published in eNeuro, indicate that the executive network’s nodes become more centralized with age, while default mode network nodes become less centralized over time. The scientists thus associated improved performance in working memory with these differences in network connectivity. This increased connectivity could indeed improve information processing (visual information processing in the case of the “N-back" test) by decreasing the interference of network nodes that could disrupt the processing of the fractal target. While it’s scientifically accepted that the executive and default mode networks of the human brain develop mainly during early childhood (they are well established by the age of 5), this research shows that the characteristics of the key nodes (also known as "hubs") in these networks continue to change into adulthood.

The authors of the study believe that these changes in brain connectivity may underlie the refinement of cognitive abilities seen during adolescence.