Teenagers who frequently play video games have more ventral striatal gray matter volume than their peers who play less often.

In a study published online November 15, 2011, in Translational Psychiatry, researchers based at Ghent University in Belgium assessed 154 healthy 14-year-old adolescents (72 males and 82 females) recruited from secondary schools in Berlin, Germany. They classified participants as frequent or infrequent players based on whether they played above or below the median of nine hours per week. Using structural magnetic resonance imaging, the researchers found significantly higher ventral striatal gray matter for frequent vs. infrequent video gamers.

“The association of video-game playing with higher ventral striatum volume could reflect altered reward processing and represent adaptive neural plasticity,” said Simone Kühn, of the Department of Experimental Psychology at the Ghent Institute for Functional and Metabolic Imaging’s Faculty of Psychology and Educational Sciences, and colleagues.

But which came first, game-playing skills or more voluminous gray matter? Kühn and colleagues said they could not determine with this cross-sectional study whether the volumetric differences in ventral striatum between frequent and moderate video-game players are preconditions that lead to a vulnerability for preoccupation with gaming or are a consequence of long-lasting activation during gaming.

“Individuals with higher ventral striatum volume might experience video gaming as more rewarding in the first place,” they wrote. “This in turn could facilitate skill acquisition and lead to further reward resulting from playing.”

The researchers also characterized the functional involvement of the regions of interest by performing two analyses. First, they analyzed brain activity occurring during a Monetary Incentive Delay task, a reaction-time task used to assess brain activity during reward anticipation and feedback. They found higher activity in the frequent video-game players while the players were being told how many points they’d won with the task. This activity was located in a region overlapping that in which they had observed higher striatal gray matter volume.

They also evaluated behavioral measures of the Cambridge Gambling Task, a behavioral task intended to measure risky decision making by subjects. A significant negative correlation between deliberation time and striatal gray matter volume was observed. The researchers said this finding indicates that participants with higher ventral striatum gray matter volume were faster in decision making.

“Our results have implications for the understanding of the structural and functional basis of excessive but nonpathological video-game playing and the role of the ventral striatum in ‘behavioral’ addiction,” said Kühn and colleagues.

Participants were recruited within the scope of the IMAGEN project, a European multicenter genetic-neuroimaging study that has recruited 2,000 14-year-old children in England, France, Ireland, and Germany since its inception in December 2007 to investigate mental health and risk-taking behavior in teenagers. The IMAGEN study receives funding from the European Community’s Sixth Framework Program.

“The Neural Basis of Video Gaming” is posted at www.nature.com/tp/journal/v1/n11/full/tp201153a.html.