Researcher gets $1.5 million to probe basis of 'internal compass'

BOWLING GREEN, O.—Some people, even in familiar surroundings, have difficulty identifying north from south, or east from west. But others seem to have an internal compass that, even in less familiar environs, guides them in whichever direction they need to go.

Finding the basis for this navigational ability is at the heart of research that has garnered more than $1.5 million in two overlapping National Institutes of Health (NIH) grants for Dr. Patricia Sharp, an assistant professor of psychology at Bowling Green State University. Both grants began this academic year and are spread over four years, with one totaling $953,400 and the other, about $562,250.

Navigational ability "involves complex, abstract representational and reasoning ability, similar to that thought to underlie the most sophisticated of human intellectual abilities," she said, explaining researchers’ interest in the topic. "Thus, insight into the mechanisms of navigation may also provide insight into other aspects of higher thought."

Agreeing with that assessment was Dr. Jeansok Kim, assistant professor of psychology at Yale University.
"Dr. Sharp has performed tour de force work in this field over the years," said Kim, who was her colleague when Sharp was on the Yale psychology faculty in the 1990s.

"Based on her work and from those of others, Dr. Sharp has proposed a very elegant and intriguing neural circuitry that accounts for the neurophysiological basis of spatial navigation in rats," Kim added. "In my view, her work is not only influential in the field of spatial navigation, but also has important relevance to our understanding of the basic nature of learning and memory."

Scientists think a strong sense of direction in humans—and other animals—depends upon "an internal, abstract, map-like representation of the large-scale environment" where daily activities are conducted, according to Sharp.

This internal map "presumably provides us with the ability to have a sense of our current position and directional heading within our environment, as well as the relative position of other important locations," such as home, work or school, she added.

Her work involves investigation of the brain systems behind the internal map, whose basis is likely formed, research has shown, by cells in certain regions of the brain.

One type of cell, called Head Direction cells, likely "fires" whenever a person faces a particular direction, said Sharp, who has a Ph.D. in neuroscience from the University of Colorado. "For example, one cell may fire whenever the individual faces northeast, and be completely silent when the individual faces any other direction," she explained.

"Surprisingly, although these cells seem to behave somewhat like a compass, they do not appear to be controlled by the earth’s magnetic field," she continued. "In fact, the cells can become ‘confused,’ so that a cell which fires in the northwest direction in one part of the terrain may fire in some other direction (perhaps south) when tested in a separate area."

Complementing the Head Direction cells are Place cells, which apparently fire only when the person is in a particular location, regardless of the direction faced. One cell, for instance, might fire "whenever you are in the northwest corner of your living room," she noted.

"These Head Direction and Place cells are thought to form the basis of our sense of direction and our ability to plan routes around our environment," Sharp said. Through her research, she is trying to learn details of the brain circuitry that enables the cells to keep track of where we are, and where we’re heading.

Sharp, a native of the Pontiac, Mich., area, received her master’s degree in psychology from Yale in 1979 and taught from 1990-99. She returned to the Midwest, and after one year as associate professor at the University of Illinois-Chicago College of Medicine at Rockford, has found a good fit at BGSU.

"This (psychology) department is really strong in what I do," Sharp said, citing the neuroscience research of Drs. Verner Bingman, professor of psychology, and Kevin Pang, associate professor of psychology.

Dr. Dale Klopfer, psychology department chair, noted that Sharp’s work particularly "dovetails nicely" with that of Bingman, who studies spatial cognition in birds.

With the addition of Sharp, whom he said "had established quite a strong record of research while on the faculty at Yale," and another new faculty member coming in neuroscience next year, the area is "remarkably strong" for a university of Bowling Green’s size, Klopfer added.

While still at Yale, Sharp received a three-year, roughly $250,000 award from NIH in 1997, and grants totaling approximately $249,000 from the National Science Foundation.

In 2000, Sharp received the D.G. Marquis Behavioral Neuroscience Award from the American Psychological Association for the best paper published in the journal Behavioral Neuroscience, and last year she edited a book, "The Neural Basis of Navigation: Evidence from Single Cell Recording." (Posted June 7, 2002)