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 Research from Imperial College London, recently published in the
scientific journal Neurology, explained how motion sickness occurs
when what the eyes see and what the inner ear senses are confused.
Clinical scientist Dr Qadeer Arshad hit upon the idea for treating
motion sickness when investigating what can influence a person's
sense of balance.
"We know that people without a functioning balance system are almost
immune or highly resistant to developing the cardinal symptoms of
motion sickness, which are nausea and vomiting. And so we developed
a separate line of research; a way of using brain stimulation to
suppress the signals from the inner ear and the brain. And so we
thought that if we suppress signals at the level of the brain from
the inner ear, then this would be highly effective against motion
sickness," Arshad told Reuters.
Most people are prone to a mild queasy feeling at some point, for
example on boats or rollercoasters. But around three in ten people
suffer from a more severe type of motion sickness, leading to more
unpleasant symptoms, such as dizziness, severe nausea and cold
sweats.
Professor Michael Gresty, a world expert on motion sickness,
collaborated in the study at Imperial College London. He said it's
the conflict in the brain that triggers these feelings of nausea as
it struggles to figure out what position the body is in.
"The reason that we can't understand these motions; the brain if you
like can't understand these motions, is that there's continual
conflict between what is upright and whether you should lean to
balance yourself in the environment or whether you're actually
experiencing a sideways acceleration force. You imagine being on a
bicycle or a motorbike; you go round a corner, you lean into the
corner which remains perfectly upright in physics. You don't so that
in a car, you don't do that on a ship - you're actually struggling
to find out what is upright and what's the best way of dealing with
it," said Gresty.
During experiments carried out at the Department of Neuro-otology at
Charing Cross Hospital, test subjects were first asked to sit in a
motorized rotating chair that also tilts to simulate the motions
that tend to make people sick on boats or rollercoasters.
Arshad said this was to determine each individual's vulnerability to
motion sickness: "What we wanted to do was compare each individual
to themselves, because people have varying degrees of
susceptibility. So we initially go people on the chair and found out
how susceptible they were, so we measured how long it took them to
develop motion sickness. We then applied a stimulation; either the
test or the control, i.e. the placebo. And then we re-measured how
long it took to develop motion sickness."
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Subjects were rotated at 72 degrees per second, equaling one
revolution every five seconds, with the chair tilted at 17 degrees.
Arshad said this generated a frequency that is particularly
nauseagenic.
Once their level of susceptibility had been determined, volunteers
wore electrodes on their heads for about 10 minutes while again
undergoing motion in the simulator. Known as transcranial direct
current stimulation (tDCS), the application of a mild electrical
current to the scalp caused the brain to suppress responses in an
area responsible for processing motion signals. Volunteers found
that they were less likely to feel nauseous and they recovered more
quickly.
"So what we found was that when we used the test condition, we found
that it took longer for the individual to develop motion sickness
and that they also recovered faster. Whereas in the control group
they developed motion sickness sooner than the first time and they
took longer to recover," added Arshad.
After further lab based experiments, Arshad says the next step is to
field test the device to determine how quickly it can speed up a
person's adaptability to motion sickness in the real world.
The researchers are confident that within ten years a consumer
device could be readily available; one that the user could simply
plug into their smart phone and attach to their scalp. They say the
electrical currents are so small that there is no reason to expect
any adverse effects from short term use.
"The technique has been around for some time, we've been using it
for a long time. And for these very small amounts of electricity
that you're putting through the brain there are no reported unwanted
side effects or interactions," said Gresty.
"So the chances of it becoming a commercially viable prospect are
quite imminent really," he added.
(The story has been refiled to correct spelling of 'device' in
headline)
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