Ever wondered how ballerinas can endlessly spin without getting dizzy?
Scientists have found that years of training cause structural differences in the brains of ballet dancers that prevent them from feeling dizzy when they perform pirouettes.
Researchers have long puzzled over how ballet dancers can perform multiple pirouettes with little or no feeling of dizziness.
Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving.
After turning around rapidly, the fluid continues to move, which can make you feel like you're still spinning.
However, ballet dancers can suppress signals from the balance organs in the inner ear, researchers found.
The finding could help improve treatment for patients with chronic dizziness.
Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers'.
The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped.
The researchers also measured eye reflexes triggered by input from the vestibular organs. Later, they examined the participants' brain structure with MRI scans.
In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than the comparison group.
The brain scans revealed differences between the groups in two parts of the brain: an area in the cerebellum where sensory input from the vestibular organs is processed and in the cerebral cortex, which is responsible for the perception of dizziness.
The area in the cerebellum was smaller in dancers. Dr Barry Seemungal, from the Department of Medicine at Imperial, thinks this is because dancers would be better off not using their vestibular systems, relying instead on highly co-ordinated pre-programmed movements.
"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," Seemungal said.
"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," Seemungal added.
