Traveling makes us feel sick because modern transport tricks the brain into thinking we have been poisoned, a neuroscientist has said.
一位神经系统科学家表示，现代交通工具会诱导大脑认为我们已经中毒，所以旅行常常使我们感到不舒服。
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'.
'If you are sitting in a ship, you're looking at a static environment, so there's no information for the eyes to say 'we are moving'.
'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.
'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.'
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.
The feeling of sickness could be relieved by looking out of a car window because this showed the brain movement was taking place.
'You can see the passage and movement itself, so that balances the system,' he said.
'The brain's going: 'Oh, look, things moving - I must be moving' - and then sort of calms down the sickness response.'
相关单词：nausea
nausea解释：n.作呕，恶心；极端的憎恶(或厌恶)
nausea例句：
Early pregnancy is often accompanied by nausea.怀孕期常有恶心的现象。
He experienced nausea after eating octopus.吃了章鱼后他感到恶心。
相关单词：toxin
toxin解释：n.毒素，毒质
toxin例句：
Experts have linked this condition to a build-up of toxins in the body.专家已把这一病症与体内毒素的积累联系起来。
Tests showed increased levels of toxin in shellfish.检验表明水生有壳动物的毒素水平提高了。
相关单词：vomiting
vomiting解释：吐
vomiting例句：
Symptoms include diarrhoea and vomiting. 症状有腹泻和呕吐。
Especially when I feel seasick, I can't stand watching someone else vomiting." 尤其晕船的时候，看不得人家呕。”
相关单词：physically
physically解释：adj.物质上，体格上，身体上，按自然规律
physically例句：
He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。
相关单词：stationary
stationary解释：adj.固定的，静止不动的
stationary例句：
A stationary object is easy to be aimed at.一个静止不动的物体是容易瞄准的。
Wait until the bus is stationary before you get off.你要等公共汽车停稳了再下车。
相关单词：sensors
sensors解释：n.传感器，灵敏元件( sensor的名词复数 )
sensors例句：
There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句
相关单词：sensory
sensory解释：adj.知觉的，感觉的，知觉器官的
sensory例句：
Human powers of sensory discrimination are limited.人类感官分辨能力有限。
The sensory system may undergo long-term adaptation in alien environments.感觉系统对陌生的环境可能经过长时期才能适应。
相关单词：evolutionary
evolutionary解释：adj.进化的；演化的，演变的；[生]进化论的
evolutionary例句：
Life has its own evolutionary process.生命有其自身的进化过程。
These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
相关单词：essentially
essentially解释：adv.本质上，实质上，基本上
essentially例句：
Really great men are essentially modest.真正的伟人大都很谦虚。
She is an essentially selfish person.她本质上是个自私自利的人。
