Route-learning changes brain tissue
Carnegie Mellon University scientists discovered that learning direction can change the brain.
Published in NeuroImage, Tim Keller and Marcel Just show for the first time that brief navigation training changes a person’s brain tissue and improves how that changed tissue communicates with other brain areas involved with navigation.
“The hippocampus has long been known to be involved in spatial learning, but only recently has it been possible to measure changes in human brain tissues as synapses become modified during learning,” said Keller, a senior research scientist in CMU’s Department of Psychology and Center for Cognitive Brain Imaging (CCBI). “Our findings provide a better understanding of what causes the hippocampal changes and how they are related to communication across a network of areas involved in learning and representing cognitive maps of the world around us.”
To examine how the hippocampus changes, Keller and Just recruited 28 young adults with little experience playing action video games. For 45 minutes, the participants played a driving simulation game. One group practiced maneuvering along the same route 20 times. The control group drove for the same amount of time, but along 20 different routes. Before and after each training session, each participant’s brain was scanned using diffusion-weighted imaging (DWI),which measures water molecule movement in the brain,and functional magnetic resonance imaging (fMRI), which analyzes brain activity.
The researchers found that the group that practiced the same route over and over — the spatial learning group — increased their speed at completing the driving task more than the group practicing on different routes, indicating that they learned something specific about the spatial layout of the virtual environment. The spatial learning group also improved their ability to order a sequence of random pictures taken along the route and to draw a 2-D map representing the route.
Importantly, only the spatial learning group showed brain structural changes in a key spatial learning part of the hippocampus, the left posterior dentate gyrus. There also were increases in the synchronization of activity – or functional connectivity – between this region and other cortical areas in the network of brain regions responsible for spatial cognition. And, the amount of the structural change was directly related to the amount of behavioral improvement each person showed on the task.
“The new discovery is that microscopic changes in the hippocampus are accompanied by rapid changes in the way the structure communicates with the rest of the brain,” said Just, the D.O. Hebb University Professor of Psychology in the Dietrich College of Humanities and Social Sciences and director of the CCBI. “We’re excited that these results show what re-wiring as a result of learning might refer to. We now know, at least for this type of spatial learning, which area changes its structure and how it changes its communication with the rest of the brain.”
