A new study reveals that habitual players of action games have less grey matter in their hippocampus, a major part of the brain. And the more depleted the hippocampus becomes, the more a person is at risk of developing brain illnesses and diseases ranging from depression to schizophrenia, PTSD and Alzheimer's disease. Shaped like a seahorse, hence its name, the hippocampus is the part of the brain that helps people to orient themselves (so-called spatial memory) and to remember past experience (episodic memory). However, there's another important part of the brain called the striatum that counterbalances the hippocampus. It has an area known as the caudate nucleus that acts as a kind of "autopilot" and "reward system" – getting us home from work, for example, and telling us when it's time to eat, drink, have sex and do other things that keep us alive and happy. The caudate nucleus also helps us form habits and remember how to do things like ride a bicycle. Gaming has been shown to stimulate the caudate nucleus more than the hippocampus; 85 per cent of players rely on that part of the brain to navigate their way through a game. The problem is, the more they use the caudate nucleus, the less they use the hippocampus, and as a result the hippocampus loses cells and atrophies, the new study shows. Specifically, patients with Parkinson's disease combined with dementia, as well as those with Alzheimer's disease, schizophrenia, depression or PTSD – all of whom have less grey matter in their hippocampus – would not be advised to follow action video game treatments, according to the study.
To do their investigation, the researchers recruited close to 100 people (51 men, 46 women) at UdeM and got them to come in and play a variety of popular shooter games like Call of Duty, Killzone and Borderlands 2, as well as 3D games from the Super Mario series, for a total of 90 hours. To establish which participants were spatial learners (that is, those who favoured their hippocampus) versus response learners (those using the reward system), the team first had each of them run through a ‘4-on-8’ virtual maze on their computer. From a central hub, they had to navigate down four identical-looking paths to capture target objects, then, after their gates were removed, go down the four others. To remember which paths they'd already been down and not waste time looking for the objects they'd already taken, spatial learners oriented themselves by the landmarks in the background: a rock, a mountains, two trees. Response learners didn't do that; they ignored the landmarks and concentrated instead on remembering a series of right and left turns in a sequence from their starting position. Once their learning strategy was established, participants then began playing the action and 3D-platform video games. The same amount of screen time on each produced very different effects on the brain. Ninety hours of playing action games led to hippocampal atrophy in response learners, while 90 hours of playing 3D games led to increased grey matter within the hippocampal memory system of all participants.