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.

KEVIN C MOORE
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Notes from a small island: the fraught and colourful history of Sicily

Sicily: Culture and Conquest at the British Museum.

When a gun was fired a hundred metres or so from the Sicilian piazza where we were eating, my reaction was to freeze, fall to my knees, and then run for cover in a colonnade. As I peered back into the square from behind a column, I expected to see a tangle of overturned chairs and china but I watched instead as the freeze-frame melted into normality. I retrieved my shoe from the waiter.

I should not have been surprised by how coolly everyone else handled what I was inclined to call “the situation”. The Sicilians have had 4,000 years in which to perfect the art of coexistence, defusing conflict with what strikes outsiders as inexplicable ease, rendering Sicily one of the most culturally diverse but identifiable places on the planet. Still, having visited “Sicily: Culture and Conquest” at the British Museum, I feel vindicated. There may be no Cosa Nostra in this exhibition, which charts the island’s history from antiquity to the early 13th century, but that doesn’t mean there is no simmering conflict. Like Lawrence Durrell, who described Sicily as “thrown down almost in mid-channel like a concert grand” and as having “a sort of minatory, defensive air”, I felt the tension beneath the bliss that has characterised Sicily for many centuries.

The “barbarians”, wrote the Greek historian Thucydides, moved to Sicily from Iberia (Spain), Troy and Italy before the Phoenicians and Greeks settled there in the 8th century BC – the time of Homer, whose Odyssey provided a useful guide to some of the more threatening features of the landscape. The giant, sea-lying rocks off the east coast were the boulders that the one-eyed Polyphemus hurled at Odysseus’s ship; the phrase “between Scylla and Charybdis” referred to the Strait of Messina that divides Sicily from the mainland; Lake Pergusa, in the centre of the island, was the eerie spot whence Hades snatched Persephone and carried her down to the underworld.

It is a delight to behold the British Museum’s case full of terracotta figurines of Persephone, Demeter and their priestesses, some of thousands uncovered across Sicily, where the Greeks established the cult of these goddesses. The Phoenicians introduced their
own weather god, Baal Hammon, and the indigenous Sicilians seem to have accepted both, content that they honoured the same thing: the island’s remarkable fecundity.

The early Sicilians were nothing if not grateful for their agriculturally rich landscapes. As early as 2500 BC, they were finding ways to celebrate their vitality, the idea being that if the soil was fertile, so were they. On a stone from this period, intended as a doorway to a tomb, an artist has achieved the near impossible: the most consummate representation of the sexual act. Two spirals, two balls, a passage and something to fill it. The penis is barely worth mentioning. The ovaries are what dominate, swirling and just as huge as the testicles beneath them. We see the woman from both inside and out, poised on two nimble, straddling legs; the man barely figures at all.

Under the Greeks in the 5th century BC, it was a different story. Although many of Sicily’s tyrants were generous patrons of the arts and sciences, theirs was a discernibly more macho culture. The second room of the exhibition is like an ode to their sporting achievements: amid the terracotta busts of ecstatic horses and the vase paintings of wild ponies bolting over mounds (Sicily is exceptionally hilly) are more stately representations of horses drawing chariots. These Greek tyrants – or rather, their charioteers – achieved a remarkable number of victories in the Olympic and Pythian Games. Some of the most splendid and enigmatic poetry from the ancient world was written to celebrate their equestrian triumphs. “Water is best, but gold shines like gleaming fire at night, outstripping the wealth of a great man” – so begins a victory ode for Hiero I of Syracuse.

But what of the tensions? In 415BC, the Athenians responded to rivalries between Segesta and Syracuse by launching the Sic­ilian expedition. It was a disaster. The Athenians who survived were imprisoned and put to work in quarries; many died of disease contracted from the marshland near Syracuse. There is neither the space nor the inclination, in this relatively compact exhibition, to explore the incident in much depth. The clever thing about this show is that it leaves the historical conflicts largely between the lines by focusing on Sicily at its height, first under the Greeks, and then in the 11th century under the Normans – ostensibly “the collage years”, when one culture was interwoven so tightly with another that the seams as good as disappeared. It is up to us to decide how tightly those seams really were sewn.

Much is made of the multiculturalism and religious tolerance of the Normans but even before them we see precedents for fairly seamless relations between many different groups under the 9th-century Arab conquerors. Having shifted Sicily’s capital from Syracuse to Palermo, where it remains to this day, the Arabs lived cheek by jowl with Berbers, Lombards, Jews and Greek-Byzantine Sicilians. Some Christians converted to Islam so that they would be ­exempt from the jizya (a tax imposed on non-Muslims). But the discovery of part of an altar from a 9th-century church, displayed here, suggests that other Christians were able to continue practising their faith. The marble is exquisitely adorned with beady-eyed lions, frolicsome deer and lotus flowers surrounding the tree of life, only this tree is a date palm, introduced to Sicily – together with oranges, spinach and rice – by the Arabs.

Under Roger II, the first Norman king of Sicily, whose father took power from the Arabs, the situation was turned on its head. With the exception of the Palermo mosque (formerly a Byzantine church, and before that a Roman basilica), which had again become a church, mosques remained open, while conversion to Christianity was encouraged. Roger, who was proudly Catholic, looked to Constantinople and Fatimid Egypt, as well as Normandy, for his artistic ideas, adorning his new palace at Palermo and the splendidly named “Room of Roger” with exotic hunting mosaics, Byzantine-style motifs and inscriptions in Arabic script, including a red-and-green porphyry plaque that has travelled to London.

To which one’s immediate reaction is: Roger, what a man. Why aren’t we all doing this? But an appreciation for the arts of the Middle East isn’t the same thing as an understanding of the compatibilities and incompatibilities of religious faith. Nor is necessity the same as desire. Roger’s people – and, in particular, his army – were so religiously and culturally diverse that he had little choice but to make it work. The start of the Norman invasion under his father had incensed a number of Sicily’s Muslims. One poet had even likened Norman Sicily to Adam’s fall. And while Roger impressed many Muslims with his use of Arabic on coins and inscriptions, tensions were brewing outside the court walls between the
island’s various religious quarters. Roger’s death in 1154 marked the beginning of a deterioration in relations that would precipitate under his son and successor, William I, and his grandson William II. Over the following century and a half, Sicily became more or less latinised.

The objects from Norman Sicily that survive – the superb stone carvings and multilingual inscriptions, the robes and richly dressed ceiling designs – tell the story less of an experiment that failed than of beauty that came from necessity. Viewing Sicily against a background of more recent tensions – including Cosa Nostra’s “war” on migrants on an island where net migration remains low – it is perhaps no surprise that the island never lost its “defensive air”. Knowing the fractures out of which Sicily’s defensiveness grew makes this the most interesting thing about it. 

Daisy Dunn’s latest books are Catullus’ Bedspread and The Poems of Catullus (both published by William Collins)

“Sicily” at the British Museum runs until 14 August

This article first appeared in the 28 April 2016 issue of the New Statesman, The new fascism