Mental maps: Route-learning changes brain tissue

October 27, 2015

Fifteen years ago, a study showed that the brains of London cab drivers had an enlargement in the hippocampus, a brain area associated with navigation. But questions remained: Did the experience of navigating London's complex system of streets change their brains, or did only the people with larger hippocampi succeed in becoming cab drivers?

Now, Carnegie Mellon University scientists have determined that learning detailed navigation information causes the hippocampal brain changes. Published in NeuroImage, Tim Keller and Marcel Just show 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 findings establish a critical link between structural and functional brain alterations that happen during spatial learning. They also illustrate that the changes are related to how neural activity synchronizes - or communicates - between the hippocampus and other regions that are important for navigation understanding and learning.

"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."

This is not the first brain research breakthrough to happen at Carnegie Mellon. CMU is the birthplace of artificial intelligence and cognitive psychology and has been a leader in the study of brain and behavior for more than 50 years. University researchers have performed some of the first mind-reading studies using fMRI, they created some of the first cognitive tutors, helped to develop the Jeopardy-winning Watson, founded a groundbreaking doctoral program in neural computation, and completed cutting-edge work in understanding the biological basis of autism. Building on its strengths in biology, computer science, psychology, statistics and engineering, CMU launched BrainHub, an initiative that focuses on how the structure and activity of the brain give rise to complex behaviors.
-end-
The Office of Naval Research funded this research.

For more information, visit the CCBI at http://www.ccbi.cmu.edu/.

Carnegie Mellon University

Related Hippocampus Articles from Brightsurf:

Brain remapping dysfunction causes spatial memory impairment in Alzheimer's disease
A research group elucidated the brain circuit mechanism that cause of spatial memory impairment in Alzheimer's disease.In the future, improving brain remapping function may reverse spatial memory impairment in patients with Alzheimer's disease.

Impact of family income on learning in children shaped by hippocampus in brain
A new study by a team of researchers at the University of Toronto identifies the region of the brain's hippocampus that links low income with decreased memory and language ability in children.

Inhibitory interneurons in hippocampus excite the developing brain
A new study from the George Washington University, however, reports that in some critical structures of the developing brain, the inhibitory neurons cause excitation rather than suppression of brain activity.

A good blood supply is good for memory
Memory performance and other cognitive abilities benefit from a good blood supply to the brain.

Scientists identify circuit responsible for building memories during sleep
Neuroscientists at the University of Alberta have identified a mechanism that may help build memories during deep sleep, according to a new study.

Lack of oxygen doesn't kill infant brain cells, as previously thought
Research, conducted at OHSU and published in the Journal of Neuroscience, raises new concerns about the vulnerability of the preterm brain to hypoxia.

Schizophrenia: Adolescence is the game-changer
Schizophrenia may be related to the deletion syndrome. However, not everyone who has the syndrome necessarily develops psychotic symptoms.

How the olfactory brain affects memory
How sensory perception in the brain affects learning and memory processes is far from fully understood.

Penn researchers discover the source of new neurons in brain hippocampus
Researchers have shown, in mice, that one type of stem cell that makes adult neurons is the source of this lifetime stock of new cells in the hippocampus.

Scientists find first evidence for necessary role of the human hippocampus in planning
A team of scientists reports finding the first evidence that the human hippocampus is necessary for future planning.

Read More: Hippocampus News and Hippocampus Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.