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Sloan fellow studies how we find our way

March 31, 2011

A UC Davis psychologist who uses live monitoring of the brains of neurosurgery patients to study how we memorize locations and directions has found his way to a prestigious Sloan Research Fellowship. The fellowship from the Alfred P. Sloan Foundation is worth $50,000 over two years.

"We’re trying to measure how the brain codes spatial information," said Arne Ekstrom, assistant professor in the Department of Psychology and at the UC Davis Center for Neuroscience.

Most of what we know about navigational memory comes from studying rodents. Rats are very good — much better than humans — at remembering their way through a maze, Ekstrom said. On the other hand, they lack a uniquely human ability: They cannot use a map.

If we can understand how navigational memory works, perhaps we can come up with strategies to help patients with dementia, Ekstrom said. Disorientation, or loss of navigational memory, is often one of the first signs of Alzheimer's disease.

 

Ekstrom works with both healthy volunteers and with patients preparing for brain surgery who volunteer to take part. He has been working with two UC Davis epilepsy specialists, Masud Seyal and Lisa Bateman, to make measurements from their patients.

 

Some people with severe epilepsy that does not respond to drug treatment are treated with brain surgery. Prior to surgery, these patients may have electrodes implanted in their brains to determine where their seizures originate and whether they are candidates to proceed with epilepsy surgery.

 

During their hospital stays, some of these patients, who are typically quite young and otherwise healthy, have volunteered to take Ekstrom's memory tests as their brain activity is recorded.

While many medical centers offer this kind of surgery, UC Davis is one of a very few sites in the world to also conduct research with these patients, Ekstrom said. His lab also runs similar tests on healthy volunteers wearing an external skull cap that picks up electrical activity in the brain.

A typical experiment looks like a video game played on a laptop computer. The volunteers steer their way around a virtual townscape, completing a task such as picking up and dropping off a passenger at a given location.

Ekstrom's team has studied, for example, a type of brain wave called the theta oscillation. In rats, this oscillation is seen when the animal is moving. But in humans, it seems to have a more complex role and is active when the brain is updating spatial information.

They have also found that the way we memorize information from a map is different from the way we learn a route by experience. When people learn a route by driving around the virtual town, they form a series of connections. But when they learn from a map, they remember relationships of multiple items to each other.

Ekstrom gained his bachelor's degree from Brandeis University in 1996 and worked as a research assistant at Harvard University before taking his master's degree at the University of Arizona (2001) and Ph.D. at Brandeis University (2004). He was a postdoctoral fellow at UCLA before joining UC Davis in 2009.

About UC Davis

UC Davis is a global community of individuals united to better humanity and our natural world while seeking solutions to some of our most pressing challenges. Located near the California state capital, UC Davis has more than 34,000 students, and the full-time equivalent of 4,100 faculty and other academics and 17,400 staff. The campus has an annual research budget of over $750 million, a comprehensive health system and 13 specialized research centers. The university offers interdisciplinary graduate study and 99 undergraduate majors in four colleges and six professional schools.

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