Being in a car, train, boat or plane causes conflicting signals in the brain which trigger a reaction similar to that which occurs when someone is poisoned.
Dr Dean Burnett, of Cardiff University, said the feeling of nausea is caused because the brain thinks the body needs to remove a toxin through vomiting.
But in fact, the ’poisoning’ effect is caused by the mixed messages from the muscles – which tell the brain the body is motionless – and the ears, which sense movement.
Speaking on the US radio show Fresh Air, Dr Burnett said that the body had not yet evolved to cope with the sensation of being in vehicles, where the body is being moved without performing movements itself.
He said: ’When we’re in a vehicle like a car or a train or a ship especially, you’re not actually physically moving... Your muscles are saying ’we are stationary’.
But the fluids in your ears, they obey the laws of physics. And they are sort of rocking around and sloshing because you are actually moving.
“但是你耳朵里的液體遵循物理定律,你確實在移動,因此它們四處搖擺、晃動。
So what’s happening there is the brain’s getting mixed messages. It’s getting signals from the muscles and the eyes saying "we are still" and signals from the balance sensors saying ’we’re in motion’. Both of these cannot be correct. There’s a sensory mismatch there.
And in evolutionary terms, the only thing that can cause a sensory mismatch like that is a neurotoxin or poison. So the brain thinks, essentially, it’s been being poisoned.
When it’s been poisoned, the first thing it does is get rid of the poison, aka throwing up.’
“當(dāng)中毒的時候,首先要做的就是排毒,也就是嘔吐。”
He explained that reading in a car made the sensation of travel sickness worse, because the eyes were focused on a small, static space and gave the brain no information to explain that the body was moving.
Dr Burnett, who was discussing his new book ’Idiot Brain: what your head is really up to’, said brain systems became more refined and efficient as people aged but that children were more susceptible to travel sickness because their brains were still developing.