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.

GERRY BRAKUS
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“Like a giant metal baby”: whether you like it or not, robots are already part of our world

For centuries, we have built replacements for ourselves. But are we ready to understand the implications?

There were no fireworks to dazzle the crowd lining the streets of Alexandria to celebrate Cleopatra’s triumphant return to the city in 47BC. Rather, there was a four-and-a-half-metre-tall robotic effigy of the queen, which squirted milk from mechanical bosoms on to the heads of onlookers. Cleopatra, so the figure was meant to symbolise, was a mother to her people.

It turns out that robots go back a long way. At the “Robots” exhibition now on at the Science Museum in London, a clockwork monk from 1560 walks across a table while raising a rosary and crucifix, its lips murmuring in devotion. It is just one of more than 100 exhibits, drawn from humankind’s half-millennium-long obsession with creating mechanical tools to serve us.

“We defined a robot as a machine which looks lifelike, or behaves in lifelike ways,” Ben Russell, the lead curator of the exhibition, told me. This definition extends beyond the mechanisms of the body to include those of the mind. This accounts for the inclusion of robots such as “Cog”, a mash-up of screws, motors and scrap metal that is, the accompanying blurb assures visitors, able to learn about the world by poking at colourful toys, “like a giant metal baby”.

The exhibits show that there has long existed in our species a deep desire to rebuild ourselves from scratch. That impulse to understand and replicate the systems of the body can be seen in some of the earliest surviving examples of robotics. In the 16th century, the Catholic Church commissioned some of the first anthropomorphic mechanical machines, suggesting that the human body had clockwork-like properties. Models of Jesus bled and automatons of Satan roared.

Robots have never been mere anatomical models, however. In the modern era, they are typically employed to work on the so-called 4D tasks: those that are dull, dumb, dirty, or dangerous. A few, such as Elektro, a robot built in Ohio in the late 1930s, which could smoke a cigarette and blow up balloons, were showmen. Elektro toured the US in 1950 and had a cameo in an adult movie, playing a mechanical fortune-teller picking lottery numbers and racehorses.

Nevertheless, the idea of work is fundamental to the term “robot”. Karel Čapek’s 1920s science-fiction play RUR, credited with introducing the word to the English language, depicts a cyborg labour force that rebels against its human masters. The Czech word robota means “forced labour”. It is derived from rab, which means “slave”.

This exhibition has proved timely. A few weeks before it opened in February, a European Parliament commission demanded that a set of regulations be drawn up to govern the use and creation of robots. In early January, Reid Hoffman and Pierre Omidyar, the founders of LinkedIn and eBay respectively, contributed $10m each to a fund intended to prevent the development of artificial intelligence applications that could harm society. Human activity is increasingly facilitated, monitored and analysed by AI and robotics.

Developments in AI and cybernetics are converging on the creation of robots that are free from direct human oversight and whose impact on human well-being has been, until now, the stuff of science fiction. Engineers have outpaced philosophers and lawmakers, who are still grappling with the implications as autonomous cars roll on to our roads.

“Is the world truly ready for a vehicle that can drive itself?” asked a recent television advert for a semi-autonomous Mercedes car (the film was pulled soon afterwards). For Mercedes, our answer to the question didn’t matter much. “Ready or not, the future is here,” the ad concluded.

There have been calls to halt or reverse advances in robot and AI development. Stephen Hawking has warned that advanced AI “could spell the end of the human race”. The entrepreneur Elon Musk agreed, stating that AI presents the greatest existential threat to mankind. The German philosopher Thomas Metzinger has argued that the prospect of increasing suffering in the world through this new technology is so morally awful that we should cease to build artificially intelligent robots immediately.

Others counter that it is impossible to talk sensibly about robots and AI. After all, we have never properly settled on the definitions. Is an inkjet printer a robot? Does Apple’s Siri have AI? Today’s tech miracle is tomorrow’s routine tool. It can be difficult to know whether to take up a hermit-like existence in a wifi-less cave, or to hire a Japanese robo-nurse to swaddle our ageing parents.

As well as the fear of what these machines might do to us if their circuits gain sentience, there is the pressing worry of, as Russell puts it, “what we’re going to do with all these people”. Autonomous vehicles, say, could wipe out the driving jobs that have historically been the preserve of workers displaced from elsewhere.

“How do we plan ahead and put in place the necessary political, economic and social infrastructure so that robots’ potentially negative effects on society are mitigated?” Russell asks. “It all needs to be thrashed out before it becomes too pressing.”

Such questions loom but, in looking to the past, this exhibition shows how robots have acted as society’s mirrors, reflecting how our hopes, dreams and fears have changed over the centuries. Beyond that, we can perceive our ever-present desires to ease labour’s burden, to understand what makes us human and, perhaps, to achieve a form of divinity by becoming our own creators. 

This article first appeared in the 23 March 2017 issue of the New Statesman, Trump's permanent revolution