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.

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The Autumn Statement proved it – we need a real alternative to austerity, now

Theresa May’s Tories have missed their chance to rescue the British economy.

After six wasted years of failed Conservative austerity measures, Philip Hammond had the opportunity last month in the Autumn Statement to change course and put in place the economic policies that would deliver greater prosperity, and make sure it was fairly shared.

Instead, he chose to continue with cuts to public services and in-work benefits while failing to deliver the scale of investment needed to secure future prosperity. The sense of betrayal is palpable.

The headline figures are grim. An analysis by the Institute for Fiscal Studies shows that real wages will not recover their 2008 levels even after 2020. The Tories are overseeing a lost decade in earnings that is, in the words Paul Johnson, the director of the IFS, “dreadful” and unprecedented in modern British history.

Meanwhile, the Treasury’s own analysis shows the cuts falling hardest on the poorest 30 per cent of the population. The Office for Budget Responsibility has reported that it expects a £122bn worsening in the public finances over the next five years. Of this, less than half – £59bn – is due to the Tories’ shambolic handling of Brexit. Most of the rest is thanks to their mishandling of the domestic economy.

 

Time to invest

The Tories may think that those people who are “just about managing” are an electoral demographic, but for Labour they are our friends, neighbours and the people we represent. People in all walks of life needed something better from this government, but the Autumn Statement was a betrayal of the hopes that they tried to raise beforehand.

Because the Tories cut when they should have invested, we now have a fundamentally weak economy that is unprepared for the challenges of Brexit. Low investment has meant that instead of installing new machinery, or building the new infrastructure that would support productive high-wage jobs, we have an economy that is more and more dependent on low-productivity, low-paid work. Every hour worked in the US, Germany or France produces on average a third more than an hour of work here.

Labour has different priorities. We will deliver the necessary investment in infrastructure and research funding, and back it up with an industrial strategy that can sustain well-paid, secure jobs in the industries of the future such as renewables. We will fight for Britain’s continued tariff-free access to the single market. We will reverse the tax giveaways to the mega-rich and the giant companies, instead using the money to make sure the NHS and our education system are properly funded. In 2020 we will introduce a real living wage, expected to be £10 an hour, to make sure every job pays a wage you can actually live on. And we will rebuild and transform our economy so no one and no community is left behind.

 

May’s missing alternative

This week, the Bank of England governor, Mark Carney, gave an important speech in which he hit the proverbial nail on the head. He was completely right to point out that societies need to redistribute the gains from trade and technology, and to educate and empower their citizens. We are going through a lost decade of earnings growth, as Carney highlights, and the crisis of productivity will not be solved without major government investment, backed up by an industrial strategy that can deliver growth.

Labour in government is committed to tackling the challenges of rising inequality, low wage growth, and driving up Britain’s productivity growth. But it is becoming clearer each day since Theresa May became Prime Minister that she, like her predecessor, has no credible solutions to the challenges our economy faces.

 

Crisis in Italy

The Italian people have decisively rejected the changes to their constitution proposed by Prime Minister Matteo Renzi, with nearly 60 per cent voting No. The Italian economy has not grown for close to two decades. A succession of governments has attempted to introduce free-market policies, including slashing pensions and undermining rights at work, but these have had little impact.

Renzi wanted extra powers to push through more free-market reforms, but he has now resigned after encountering opposition from across the Italian political spectrum. The absence of growth has left Italian banks with €360bn of loans that are not being repaid. Usually, these debts would be written off, but Italian banks lack the reserves to be able to absorb the losses. They need outside assistance to survive.

 

Bail in or bail out

The oldest bank in the world, Monte dei Paschi di Siena, needs €5bn before the end of the year if it is to avoid collapse. Renzi had arranged a financing deal but this is now under threat. Under new EU rules, governments are not allowed to bail out banks, like in the 2008 crisis. This is intended to protect taxpayers. Instead, bank investors are supposed to take a loss through a “bail-in”.

Unusually, however, Italian bank investors are not only big financial institutions such as insurance companies, but ordinary households. One-third of all Italian bank bonds are held by households, so a bail-in would hit them hard. And should Italy’s banks fail, the danger is that investors will pull money out of banks across Europe, causing further failures. British banks have been reducing their investments in Italy, but concerned UK regulators have asked recently for details of their exposure.

John McDonnell is the shadow chancellor


John McDonnell is Labour MP for Hayes and Harlington and has been shadow chancellor since September 2015. 

This article first appeared in the 08 December 2016 issue of the New Statesman, Brexit to Trump