Beyond the Nobel: What Scientists Are Learning About How Human Brains Navigate

Can you point to Center City? neuroscientist Russell Epstein likes to ask visitors to his office at the University of Pennsylvania in Philadelphia. Sometimes they can do it. Sometimes they have a little trouble. And sometimes, Epstein says, they have no idea how theyd even begin to solve that problem.

Epsteinstudies the way people navigate through space and orient to their surroundingswhich turns out to be averychallenging problem for some people. His work builds on the research in rats that earned three scientists the Nobel Prize in Physiology or Medicine this morning.The prize-winning work identified certain types of neurons in the brain that are integral to the brains internal navigation system.

Epstein is one of several researchers trying to connect the dots between thatrodent research and individual differences in peoples ability toorient to their surroundings and find their way from one place to another. As you may have noticed, all people are not equally good at this.

In a study published last year, hislab teamed up with psychologists from nearby Temple University to investigate what happens as people get to know a new place over the course of a few weeks. They took Temple students to a suburban campus theyd never seen beforeandshowed them two short walking routesthatpassed by four buildings that served as landmarks. To keep the students from making a connection between the two routes, they blindfolded them and pushed them in wheelchairs from one to the other.

In subsequent visits, the researchers showed the students two different paths that connected the two routes theyd learned. Then they did some tests to try to see which students had put all the pieces together into a mental map of the new campus. For example, theyd ask a student to imagine standing in front of one of the eight buildings and point to the other seven. Some people could do it well, and other people couldnt do it all that well, Epstein said. Thats not terribly surprising. What he and his colleagues really want to know is whats going on in the students brains that might account for that difference.

When theydidMRI scans of the brains of 13 of the students, theyfound a correlation between the size of the right hippocampusa region with important roles in memory and navigation, and the focus of the Nobel-winning researchand how well a person had done on the imaginary pointing task. That suggests to Epstein that people with a bigger right hippocampus, and even more specifically, the posterior or back end of the right hippocampus, may be better able to get oriented to new places.

Its just one study, and a fairly small one at that, but the findings fit with other research. The most famous of these are the cab driver studies by Eleanor Maguire and her colleagues at University College London. Since the early 2000s, Maguire and her team have studied London cabbies as they learn The Knowledge, the navigational wherewithal to get a passenger from point A to B through the citys medieval maze of streets without looking at a map or using GPS as a crutch.

London streets. Map: OpenStreetMap contributors

A few years ago, Maguires team scanned the brains of 79 cabbie wannabes just about to embark on the three to four year training program, and they scanned most of them again afterwards (only 39 had managed to pass the qualifying examLondon is confusing!). MRI scans showed that the posterior hippocampus had gotten slightly larger in those whod successfully crammed The Knowledge into their heads. Those who flunked out showed no change, the researchers reported in Current Biology.

Epstein says those findings show pretty convincingly that intensive geographical training can increase the volume of the posterior hippocampus. Its the same area Epsteins campusnavigation study implicated, but in that case he suspectsthe students performance was impacted by pre-existing differences in their brains. People came in with these differences [in the size of their posterior hippocampus] and that affected how well they learned the campus, he said.

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Beyond the Nobel: What Scientists Are Learning About How Human Brains Navigate