英語聽力文摘549 中樞痛成因你知多少？
- 聽力原文
- 參考譯文
What would it be like if wearing a soft cotton t-shirt felt like your skin was being scrubbed with a Brillo pad? For people who suffer from a condition called central pain, such pain is all too familiar.
Central Pain on this moment of science.
No one’s sure why some people suffer agonizing pain at the slightest touch, but the secret may lie in an area of the brain called the thalamus, which acts as a gateway for all sensory messages processed by the brain. Nerve cells known as neurons relay messages to the thalamus, which passes the messages to a set of neurons that carry the messages to other areas of the brain.
Different sets of neurons bring pain and touch signals into the thalamus, but both types of messages are passed to other areas of the brain by one set of outgoing neurons.
So how does the brain distinguish between signals of touch and pain? Messages of touch trigger the release of a chemical called GABA, which diminishes the intensity of the outgoing message. But messages of pain don’t seem to cause GABA to be released, so they come through at full strength.
GABA might be muting some messages by altering their length. Messages of touch might cause a brief burst of information and then be shut off by GABA, while messages of pain continue to fire, unimpeded by GABA. In people who suffer from central pain, GABA might NOT be released in response to messages of touch. With no GABA to turn the touch signal down, every signal of touch may be read as one of pain.
中樞痛成因你知多少?
當(dāng)你穿上一件棉布T恤，感到皮膚像是被鋼絲球來回擦拭時(shí)，是什么滋味?對那些患有中樞痛的患者來說，這種感覺太常見了。
本期的科學(xué)一刻就讓我們來討論討論中樞性疼痛。
為何某些人僅被稍微觸碰就會感到劇痛?沒人知道確切原因，但其中奧妙可能存在于大腦中一處名為丘腦的區(qū)域，丘腦是所有經(jīng)大腦處理的感知信息的中轉(zhuǎn)站。被稱為“神經(jīng)元”的神經(jīng)細(xì)胞將信息轉(zhuǎn)播給丘腦，丘腦再將信息傳送給一組神經(jīng)元，最后由它們將信息傳播至大腦其他區(qū)域。
不同的神經(jīng)元將疼痛和觸覺信號傳送給丘腦，但這兩類信號由同一組輸出神經(jīng)元傳送到大腦的其他區(qū)域。
那么大腦是如何區(qū)分疼痛和觸覺信號的?觸覺信息會引發(fā)一種名為γ-氨基丁酸(GABA)的化學(xué)元素釋出，該元素減弱所輸出信息的強(qiáng)度。但疼痛信息并不能引發(fā)GABA的釋放，因此它們會完全傳播。
GABA可能通過改變信息長度來更改某些信息。觸覺信息可能會引發(fā)信息的短簇脈沖，隨后GABA將其切斷，而疼痛信息不受GABA的阻礙，繼續(xù)橫行。在那 些患有中樞性疼痛的人中，觸覺信息不會引發(fā)GABA的釋出。當(dāng)沒有GABA屏蔽觸覺信號時(shí)，每一觸覺信號都被誤讀為疼痛。
