A Balanced Approach

The tightrope walker, confidently strolling on a thin wire suspended a hundred feet in the air, is saved from death by a finely tuned sense of balance. For a quarter century, Marjorie Woollacott has delved into the mysteries that keep the tightrope walker--and the rest of us--upright.
"What mechanisms in our brains provide this remarkable sense?" she asks.
Woollacott, head of the University of Oregon's Department of Exercise and Movement Science, uses a complicated piece of machinery informally known as "the electronic banana-peel" to conduct much of her research. The device consists of a walkway with hydraulically controlled plates that slip out from under research subjects, as if they had encountered Charlie Chaplin's discarded banana peel. (Unlike the pratfalling participants in slapstick sight gags, however, volunteer research subjects are kept safe by protective harnesses.) "In the past, most balance research was static, that is, based on subjects standing and receiving a jolt, as if they were on a bus that lurched forward," says Woollacott, a member of the UO Institute of Neuroscience. "In contrast, we study people in motion, where they are more likely to fall."
One study investigates balance in children in order to learn the course of normal development. This knowledge is vital for understanding--and possibly devising treatments for--abnormal development such as that seen in children with cerebral palsy.
Woollacott's lab was also one of the first to look at balance in senior citizens--seeking insights into why, each year, tens of thousands of older adults lose their balance, fall, and suffer injuries ranging from bruises to broken hips.
Some of her research has focused on the initiation of falls. To various degrees in various circumstances, three senses contribute to balance: vision, the balance center in the inner ear, and, simply put, touch (really a complex interplay of nerves, joint sensation, and muscle receptors). Many falls begin when older adults must quickly switch from relying primarily on one sense to another. For example, when a person walking on a firm surface such as linoleum (touch) steps onto a thick carpet, he or she must quickly switch to reliance on a visual sense of the floor's exact location.
"We learned that younger people immediately make the switch, while elders usually do so only after a few tries," Woollacott notes. Her experiments also showed that with practice older adults could switch more quickly.
Another age-related difference manifests once a loss of balance begins: younger people routinely catch themselves while older people tend to fall. Why? No one knew, so Woollacott began her investigation. She found a culprit: insufficient muscular response.
"This means that older adults who work on muscular strength--especially in their ankles, but also in their legs and hips--will have better balance and fewer falls," she says.
Woollacott developed practical applications of this knowledge in collaboration with one of her former students, UO courtesy research associate Anne Shumway-Cook.
"We started using computers and expensive machines in the laboratory to identify and explore balance problems," says Shumway-Cook, who now runs a fall-prevention program at Northwest Hospital in Seattle. "We put that information to use in a clinical setting to develop low-tech, low-cost tests and treatments. Now those tests and treatments are used in doctors' examination rooms across the country."
For her next project, Woollacott says, she is setting her sights high. "I want to find out exactly what part of the brain controls balance. This is a mystery, and solving it would shed light on many problems and possibly suggest innovative therapies."

Back to INQUIRY, Spring 1997