Ballet dancers' brains are uniquely adapted to avoid feeling dizzy, and scientists believe this discovery could help patients who suffer from chronic dizziness.
The fluid-filled vestibular organs in the inner ear sense rotation of the head with tiny hairs that sense the fluid's motion. After spinning, the fluid continues to move, leading to a feeling of dizziness.
About one in four people will experience chronic dizziness in their life, according to Dr. Barry Seemungal of Imperial College London. "Ballet dancers seem to be able to train themselves not to get dizzy, so we wondered whether we could use the same principles to help our patients."
Ballet dancers can perform multiple pirouettes -- fast rotations on one supporting leg -- without getting dizzy.
The findings, published in the journal Cerebral Cortex, show this isn't just due to "spotting," a technique where a dancer focuses their vision on one "spot" in front of them as their body rotates, quickly snapping their head back around to the "spot" to complete a spin.
Researchers recruited 29 female ballet dancers and, for comparison, 20 female rowers with similar age and fitness levels.
Participants were spun around in a chair in a dark room, and asked to turn a handle in time with how quickly they felt like they were still spinning after they stopped. Researchers measured eye reflexes triggered by input from the vestibular organs and examined participants' brains with MRI scans.
In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers. Brain scans revealed differences in an area in the cerebellum which processes input from the vestibular organs and in the cerebral cortex, which is responsible for the perception of dizziness.
"It's not useful for a ballet dancer to feel dizzy or off balance," said Seemungal. "Their brains adapt over years of training to suppress that input. Consequently, the signal going to the brain areas responsible for perception of dizziness in the cerebral cortex is reduced, making dancers resistant to feeling dizzy."
"If we can target that same brain area or monitor it in patients with chronic dizziness, we can begin to understand how to treat them better," Seemungal said.
Another finding could change how patients are tested in the clinic. In the control group, the perception of spinning closely matched the eye reflexes triggered by vestibular signals, but in dancers, the two were unconnected.
"This shows that the sensation of spinning is separate from the reflexes that make your eyes move back and forth," Dr Seemungal said. "In many clinics, it's common to only measure the reflexes, meaning that when these tests come back normal the patient is told that there is nothing wrong. But that's only half the story. You need to look at tests that assess both reflex and sensation."