Ballet dancers' brains 'adapt to spins'

Ballet dancers develop differences in their
brain structures to allow them to perform
pirouettes without feeling dizzy, a study
has found.
A team from Imperial College London said
dancers appear to suppress signals from the
inner ear to the brain.
Dancers traditionally use a technique called
"spotting", which minimises head movement.
The researchers say their findings may help
patients who experience chronic dizziness.
Train hard
Dizziness is the feeling of movement when, in
reality, you are still.
For most it is an occasional, temporary
sensation. But around one person in four
experiences chronic dizziness at some point in
their life.
When someone turns or spins around rapidly,
fluid in the vestibular organs of the inner ear
can be felt moving through tiny hairs.
Once they stop, the fluid continues to move,
which can make a person feel like they are still
spinning.
Ballet dancers train hard to be able to spin, or
pirouette, rapidly and repeatedly.
They use a technique called spotting, focusing
on a spot on the floor - as they spin, their
head should be the last bit to move and the
first to come back.
In the study, published in the journal Cerebral
Cortex, the team recruited 29 female ballet
dancers and 20 female rowers of similar age
and fitness levels.
Reflexes
After they were spun in the chair, each was
asked to turn a handle in time with how
quickly they felt like they were still spinning
after they had stopped.
Eye reflexes triggered by input from the
vestibular organs were also measured.
Magnetic resonance imaging (MRI) scans were
also taken to look at participants' brain
structures.
Dancers' perception of spinning lasted a
shorter time than rowers' - and the more
experienced the dancers, the greater the
effect,
The scans showed differences between the
dancers and the rowers in two parts of the
brain: the cerebellum, which is where sensory
input from the vestibular organs is processed,
and the cerebral cortex, which perceives
dizziness.
The team also found that perception of
spinning closely matched the eye reflexes
triggered by vestibular signals in the rowers,
but in dancers there was no such link.
Resistant
Dr Barry Seemungal, of the department of
medicine at Imperial College London, who led
the research, said: "It's not useful for a ballet
dancer to feel dizzy or off balance. Their
brains adapt over years of training to suppress
that input.
"Consequently, the signal going to the brain
areas responsible for perception of dizziness in
the cerebral cortex is reduced, making dancers
resistant to feeling dizzy."
He added: "If we can target that same brain
area or monitor it in patients with chronic
dizziness, we can begin to understand how to
treat them better."
Deborah Bull, a former principal dancer with
the Royal Ballet, who is now the executive
director of the Cultural Institute at King's
College, London, told BBC Radio 4's Today
programme: "What's really interesting is what
ballet dancers have done is refine and make
precise the instruction to the brain so that
actually the brain has shrunk. We don't need
all those extra neurons."