芭蕾舞者旋转时不会眩晕得益于大脑

Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid feeling dizzy when they perform pirouettes（脚尖旋转）. The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.

The findings, published in the journal Cerebral Cortex, could help to improve treatment for patients with chronic dizziness. Around one in four people experience this condition at some time in their lives.

Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you're still spinning.

Ballet dancers can perform multiple pirouettes with little or no feeling of dizziness. The findings show that this feat isn't just down to spotting, a technique dancers use that involves rapidly moving the head to fix their gaze on the same spot as much as possible.

Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers'.

The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped. The researchers also measured eye reflexes triggered by input from the vestibular（前庭的） organs. Later, they examined the participants' brain structure with MRI scans.

In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers.

Dr Barry Seemungal, from the Department of Medicine at Imperial, said: "Dizziness, which is the feeling that we are moving when in fact we are still, is a common problem. I see a lot of patients who have suffered from dizziness for a long time. 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."