本集內容
Why are we ticklish? 人怕撓癢癢的原因
學習要點
有關 「the body’s reactions 身體反應」 的詞彙
邊看邊答
Why isn’t being tickled always enjoyable?
文字稿
Professor Sukhi Shergill, Psychiatry and Systems Neuroscience, King’s College London
Tickling: love it, or hate it? Or even a bit of both… It’s a strange phenomenon.
蘇基‧謝吉爾 倫敦大學國王學院精神病學與系統神經科學教授
「被人撓癢癢這種感覺：你是喜歡還是討厭？或者都有一點… 這是個奇怪的現象。」
There are two types of tickling sensation. Knismesis – a mildly annoying feeling caused by light movement like this. And there’s gargalesis – which is caused by a deeper pressure on your skin.
癢的感覺分為兩種：「觸覺癢」指由這種輕撫的動作引起的輕微不適感；「逗笑癢」是通過給皮膚施加更強的力道而引發的。
When your skin is touched, the nerve endings underneath send electrical signals to the brain. We laugh when we’re tickled because the sensation is picked up in two areas of the brain at once – the part which analyses touch, but also the part that creates pleasure.
But of course, being tickled isn’t always enjoyable.
當你的皮膚被觸碰時，皮下的神經末梢會向大腦傳送電子信號。我們被人撓癢癢之後會發笑，因為這種感覺會同時出現在大腦的兩個區域中：分析觸覺的區域，以及產生愉悅感的區域。當然，被撓癢癢並不總是件令人感到愉快的事情。
In fact, it also affects the part of the brain that makes you feel panic in the face of danger.
So, strange as it may seem, laughing when you’re tickled could be a sort of primitive defence mechanism – giving a signal to show our submission to a predator.
事實上，它還會影響大腦中使你臨危恐慌的部分。所以，雖然看起來很奇怪，但被胳肢後大笑可能是一種原始的防禦機制，就好比是身體通過發送信號來展現對捕食者的順從。
So, why can’t we tickle ourselves? We think it’s to do with the brain’s cerebellum that monitors our movement. It can tell the difference between expected and unexpected sensations. In other words, it already knows what you’re doing and is too clever to react.
那麼，為什麼不能胳肢自己呢？我們認為這和小腦有關，小腦負責監控身體的運動。它能區分預期和意外的感覺之間有何不同。換言之，它已經知道你在做什麼，只是因為太聰明而不作出反應。
詞彙
tickling sensation 癢的感覺，發癢
nerve endings 神經末梢
electrical signals 電子信號
defence mechanism 防禦機制、防衛表現
問題答案
Because it affects two parts of the brain, including one that makes us feel panic.
