Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid feeling dizzy when they perform pirouettes.
The study by researchers at Imperial College London showed that extensive dance training appears to allow dancers to suppress signals from the balance organs in the inner ear. In the study, published in the journal Cerebral Cortex, the team recruited 29 female ballet dancers and 20 female rowers of similar ages and fitness levels.
After they were spun in a chair, each was asked to turn a handle in time with how quickly they felt like they were spinning and again their perception after the spinning was stopped. Eye reflexes triggered by input from the vestibular organs were measured, and magnetic resonance imaging (MRI) scans were also taken to look at participants’ brain structures.
Dancers’ perception of spinning lasted a shorter time than rowers’ – and the more experienced the dancers, the greater the effect. The scans showed differences between the dancers and the rowers in two parts of the brain: the cerebellum, which is where sensory input from the vestibular organs is processed, and the cerebral cortex, which perceives dizziness.
The team also found that perception of spinning closely matched the eye reflexes triggered by vestibular signals in the rowers, but in dancers there was no such link.
Dr Barry Seemungal, of the department of medicine at Imperial College London, who led the research, said: “It’s not useful for a ballet dancer to feel dizzy or off balance. 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.”
He added: “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.”
Another finding in the study may be important for how chronic dizzy 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 uncoupled.
“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.”