Image caption Ballet dancers train hard to be able to perform rapid pirouettes

Ballet dancers develop differences in their brain structures to allow them to perform pirouettes without feeling dizzy, a study has found.

A team from Imperial College London said dancers appear to suppress signals from the inner ear to the brain.

Dancers traditionally use a technique called "spotting", which minimises head movement.

The researchers say their findings may help patients who experience chronic dizziness.

Train hard

Dizziness is the feeling of movement when, in reality, you are still.

For most it is an occasional, temporary sensation. But around one person in four experiences chronic dizziness at some point in their life.

When someone turns or spins around rapidly, fluid in the vestibular organs of the inner ear can be felt moving through tiny hairs.

Once they stop, the fluid continues to move, which can make a person feel like they are still spinning.

Ballet dancers train hard to be able to spin, or pirouette, rapidly and repeatedly.

They use a technique called spotting, focusing on a spot - as they spin, their head should be the last bit to move and the first to come back.

In the study, published in the journal Cerebral Cortex, the team recruited 29 female ballet dancers and 20 female rowers of similar age and fitness levels.

Reflexes

After they were spun in the chair, each was asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped.

It's not useful for a ballet dancer to feel dizzy or off balance Dr Barry Seemungal , Imperial College London

Eye reflexes triggered by input from the vestibular organs were also measured.

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.

Resistant

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."

Deborah Bull, a former principal dancer with the Royal Ballet, who is now the executive director of the Cultural Institute at King's College, London, told BBC Radio 4's Today programme: "What's really interesting is what ballet dancers have done is refine and make precise the instruction to the brain so that actually the brain has shrunk. We don't need all those extra neurons."