Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid dizziness while performing pirouettes. The findings could lead to the development of dance therapy to treat patients with chronic dizziness, a condition experienced by one in four people during their lives.
LONDON, ENGLAND, UK (OCTOBER 10, 2013) (REUTERS) - Aware that ballet dancers can perform multiple pirouettes with little or no feeling of dizziness, researchers at Imperial College London led by Dr Barry Seemungal, decided to study their brains. They recruited 29 right-handed female ballet dancers and compared them to 20 female rowers of the same age range, and with similar fitness levels.
The volunteers were spun around in a chair in a dark room. Their heads were positioned in between two pads which gave little room for movement, while electrodes attached to their forehead helped track their eye movements. Volunteers 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 organs in the ear.
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. The brain scans revealed differences between the groups in two parts of the brain: an area in the cerebellum where sensory input from the vestibular organs is processed and in the cerebral cortex, which is responsible for the perception of dizziness. The findings showed 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.
"When we correlated dizziness sensation to the white matter structure in non-dancers we found a very strong correlation between how dizzy you were and the strength of a white matter network in the cerebral cortex, which is the part of the brain we use to sense and perceive things. In the dancers we did not find this correlation," said Seemungal.
The research showed that the area in the cerebellum was smaller in dancers. Seemungal thinks this is because dancers don't use their vestibular systems, relying instead on highly co-ordinated pre-programmed movements.
"The second finding that was actually surprising was the extent of the difference between the non-dancers and the dancers in the connections of the brain relating to dizziness," said Seemungal. "The difference was so stark that we rechecked our results but it was quite clear that this was a real result, and it demonstrates to us that the brain is a very plastic organ and what happens to it is heavily dependent on what you do, and so years of training the brain re-models itself into a form that becomes quite resistant to dizziness."
The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.
Dance student Clare Haven took part in the study and admitted that she had suffered some dizziness because the spinning took part in the dark, and also due to her inability to use the technique of spotting, which she learned in her early years of dancing.
"It's something that you're taught how to do, it's not something that's natural. So from a young age in ballet class you run around pretending to be a fairy, you're just turning around on the spot. Then as you get older you're taught what spotting is, so you whip your head round. As you get older you practise where your balance is," said Haven.
The findings, published in the journal Cerebral Cortex, could help to improve treatment for patients with chronic dizziness. Seemungal is seeking funding to develop a form of dance therapy, to be used by chronically dizzy patients in conjunction with medication.
"Dancing which includes an element of spinning, which is the key point about choosing dancers who spin - that is ballet dancers - in a graded and controlled fashion, that would be the way that we proceed. Now I can't give you any hard facts about this. This is an idea and we are aiming to get funding to test this idea, but we feel it is likely to be of some use," said Seemungal.
The doctor, who runs a specialist clinic for dizziness at London's Charing Cross Hospital, says dance therapy is potentially useful because it is fun, motivating patients to practise at home. Also, because patients could be treated in large groups, it might be more cost effective than current individual treatments in those patients suffering from a permanent loss of vestibular organ function, who must undergo brain re-training.
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 detect the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you're still spinning.