Ballet dancers’ brains adapt to stop them going dizzy

Years of training in “spotting”, the technique of quickly and repeatedly bringing your gaze to two specific points in front and behind you, certainly helps, but new research suggests that the brain’s ability to adapt plays a powerful role.

If you’ve ever tried spinning in circles while looking up to the sky, you’ll know the accompanying dizziness that can follow. But what stops ballet dancers, who pirouette endlessly for a living, from falling into each other like a set of dominoes?

Years of training in “spotting”, the technique of quickly and repeatedly bringing your gaze to two specific points in front and behind you, certainly helps, but new research suggests that the brain’s ability to adapt plays a powerful role. And it could help better treat and diagnose people who suffer from chronic dizziness.

Neuroscientists at Imperial College London recruited 29 female ballet dancers and spun them around in a chair in a dark room. When the chair was stopped, the dancers were asked to turn a lever to indicate how quickly they still felt they were spinning. This measured their perception response to dizziness. Eye reflexes – the quick flicking of the eyes from moving around rapidly – were also measured. In normal people, these two responses correlate well, but in the dancers there appeared to be an uncoupling: while their eye reflexes kept going, their perception response fell.

A group of 20 female rowers, who were similar in age and fitness, were also recruited as a control group. Brain scans were then taken to analyse the brain structures of all the individuals.

Powerful resistance

In cases of chronic dizziness, tests are usually taken of the vestibular organs in the inner ear. These fluid-filled organs use tiny hairs to sense the movement of the fluid, which in turn send signals to the brain. The continued movement of fluid explains one of the reasons you can continue to feel dizzy after you’ve stopped moving. But this doesn’t go far enough to explain dizziness in chronic suffers, said Barry Seemungal, co-author of the study, published in Cerebral Cortex.

“We measured sensation perception and eye reflexes and found dancers were much more resistant to non-dancers,” he said. “In the rowers, sensation correlated very well to reflexes, but in dancers the two were not correlated – they had de-coupled. In a person with chronic dizziness, the duration of their perceptual response is much longer; there’s a disproportionately higher reaction compared to a dancer who shows powerful resistance.”

An MRI scan then looked at the amount of grey matter (the bit that calculates) and the white matter (the part of the brain that makes connections) in the cerebellum. This also threw up differences between dancers and non-dancers.

“A statistical comparison between brain structures showed that in dancers an area of the cerebellum was smaller than in the rowers. This part of the brain also known to be involved in processing signals from the ear. And the more experienced the dancer, the smaller it is. The cerebellum can process signals that are then sent to areas of the brain linked to perception. In dancers it reduces the flow of signals – it acts like a gate.”

The researchers then looked at the cerebral cortex, which is associated in perception, and found stronger white matter in the control group. “More white matter means you’re more likely to be dizzy – in dancers we didn’t see it,” Seemungal said.

Seeing is believing

So how can these findings help people with chronic dizziness? For a start, we now have recognition that the brain is the organ that controls balance and, crucially, that it’s able to adapt.

“Traditional testing considers the ear as the organ of balance,” Seemungal said. “I’m a neurologist so I consider it as the brain.”

“The brain takes in lots of different information to make an assessment and compensates if it needs to. The ear is one source, vision is another. If you hear a noise to the right and move your head to look at it, your brain combines the estimates and places greater weight on the more reliable, in this case the eye.”

“But vision can be ambiguous – for example when you’re sat on a train and another one moves and you think you’re the one moving. As a general principle the brain prioritises visual motion over vestibular organs [the ear]. Another example is the ventriloquist’s doll, it combines the auditory and visual inputs but relies more on the visual so you think it’s the doll that’s talking.”

“If your vestibular organs aren’t working well, your brain won’t trust them and even trivial visual stimuli can trigger a dizzy sensation. But traditional testing relies on testing the vestibular organs, which might indicate nothing is wrong.”

People with chronic dizziness can be treated for underlying causes but also longer-term physio treatment. Depending on the form of the condition, this can include exposing them to self-motion (the swaying we all do but don’t notice if we don’t suffer from dizziness) and visual motion to get the brain more habituated.

One lucky find (for the researchers anyway) was that one of the dancers involved in the study later went on to develop chronic dizziness. This enabled the team to test her against their original findings. They found that although her reflex functions had remained the same, her perception response had become stronger.

Professor Nicky Clayton, a Professor of Comparative Cognition at Cambridge and Scientist in Residence at Rambert, the contemporary dance company, said: “As a dancer you learn tricks that allow your body to move in very flamboyant ways but without losing control. One of the tricks I learned was that when you get that sense of spinning, you use your core muscles to pull up; and that you’re disengaging with that feeling of fluidity and creating a stabilising energy.

She added: “Dancers think in very abstract ways … The way in which the brain talks to the cognitive system, whether through its plasticity or psychologically, is more than just spotting. Spotting helps you to focus but it’s not the only thing.”

Simon Lloyd, an ENT specialist, said: “The tests could potentially be useful because at the moment we have no effective way of testing how well parts of the balance system within the brain are working. Testing this would also allow us to measure how people are responding to treatment.”

The Conversation

This article was originally published at The Conversation. Read the original article.

Dancers of Cuba national ballet perform during a rehearsal for Swan Lake in Madrid in 2009. Photo: AFP/Getty Images

Jo Adetunji is the commissioning editor for health and medicine at The Conversation UK.

JOHN OGILBY/PRIVATE COLLECTION/BRIDGEMAN IMAGES
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Why did Britain's first road atlas take you to Aberystwyth?

Alan Ereira's new The Nine Lives of John Ogilby tells the story of a remarkable book – and its remarkable creator.

John Ogilby was a talented dancer with a bright future. Performing at White Hall Palace in February 1619, the 18-year-old leapt higher than ever to impress the watching James I and his queen. But then, crashing to the floor with a torn ligament, Ogilby never danced again. It was one of many misfortunes he overcame in a remarkable life. He went on to become a theatrical impresario, the deputy master of the revels in Ireland, a poet, a translator and a publisher of ancient classics. He even organised the public celebration of Charles II’s coronation. He was also an accomplished soldier, sailor and spy, as Alan Ereira reveals in this entertaining account of his “lives” and times.

It was a remarkable collection of lives for a man born in Scotland in 1600 and raised in poverty, the illegitimate son of an aristocrat. Yet Ogilby’s greatest achievement was to put Britain on the map when he was appointed “His Majesty’s Cosmographer and Geographick Printer” in 1674. His Britannia is the first detailed road atlas ever made. It opens with a map of England and Wales showing, he wrote, “all the principal roads actually measured and delineated”. It contains a hundred or so beautifully engraved plans of roads as winding ribbons sliced into sections. Rivers, forests, villages and bridges are included as landmarks.

Embracing the new science of measurement and experiment championed by the Royal Society, Ogilby’s surveyors used a wheel with a circumference of 16ft 6in and a handle that allowed it to be pushed along, as well as a clock face that recorded journey distances. With no universally agreed length of a mile, Ogilby chose 1,760 yards. Britannia led to the accurate measurement of almost 27,000 miles of tracks, paths and roads, though only about 7,500 are depicted in the atlas at one inch to the mile.

Britannia was published in September 1675. There were few who could afford it, at £5 (roughly £750 in today’s money), and it was too heavy to carry. Instead, travellers found their way around the country by following printed itineraries, with lists of the towns to pass through on any particular journey.

Britannia is not, as Ereira explains, an atlas of commercially useful roads of the day. The first journey is an odd one, from London to Aberystwyth, then a town of fewer than 100 houses and a ruined castle. Some of the roads chosen were no longer in use, while important routes such as those to Liverpool and Sheffield were left out.

But the choice of roads in Britannia begins to make sense as being those necessary for the royal mastery of the kingdom. The London to Aberystwyth road led to mines nearby. In the days of Charles I those mines contained lead and silver that helped the king pay his soldiers during the civil war. Britannia was a handbook, Ereira explains, for a conspiracy leading to a new kingdom under a Catholic king.

Ever since the start of the Reformation, Europe had been rumbling towards a religious war. When it came on the mainland it lasted 30 years and left millions dead. The subsequent Peace of Westphalia led to a new map of Europe, one of countries and defined frontiers instead of feudal territories with unclear borders and independent cities. England was not included in the peace but shared in its vision of separate sovereignty. This led to different results in different places. In France, the king became an all-powerful despot; in England it was the ruler who lost power as parliament emerged triumphant.

In 1670 Charles I’s son Charles II decided to throw off the restraints he had accepted as the price of his restored monarchy. He wanted to be the absolute master in his land. To achieve this, he entered into a secret treaty with the French king Louis XIV. Charles needed money, an army, allies to execute his plan, and detailed knowledge of the kingdom; Louis was willing to bankroll the venture as long as Charles converted to Catholicism. Britannia was a vital part of Charles’s strategy to assert military control: he would use it to help land and deploy the 6,000 French troops that Louis had promised him to assist his forces. The pact remained a well-kept secret for nearly a century, even though it soon fell apart when the French and British got bogged down in a war with the Dutch.

No matter. Ogilby died in September 1676 and in 1681 Charles II dissolved parliament for the last time during his reign. “Britannia provided an extraordinary grasp over the business and administration of the 399 communities that it identified in England and Wales, and the crown took a grip on them all,” Ereira writes.

In this way, the atlas played a significant part in enabling the king’s revenue to grow by one-third within a few years. No longer needing financial help from Louis, Charles ruled by divine right, exercising absolute power until his death in 1685. The lesson of Britannia was that whoever controls the map controls the world.

Manjit Kumar is the author of “Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality” (Icon)

This article first appeared in the 12 January 2017 issue of the New Statesman, Putin's revenge