手機版
for National Geographic News
Published October 3, 2011
Millions of receptors in the nose's smelling organ aren't scattered at random, a new study says. Instead, the receptors congregate in tiny hot spots that help the brain discern good smells from bad ones, among other potential functions.
一項新的研究表明，鼻腔內數以百萬計的嗅覺受體并不是隨機分布的。而是聚集在一些微小的區域里，它們可以幫助大腦辨別氣味的好壞，同時還具備其他一些潛在的功能。
The evidence was gathered by sticking electronic probes up people's noses and measuring the chatter of nasal neurons as subjects were exposed to scents.
實驗證據的收集是依靠一些電子探針。研究人員將電子探針插入受試者鼻腔內，測量受試者在嗅聞各種氣味時嗅覺神經元所產生的信號變化。
The findings imply that the pleasantness of a smell is hardwired within our heads, calling into question the impact of life experience on how people perceive smells.
研究結果表明，辨別氣味好壞的神經通路先天就隱藏在人類的大腦里。問題就是后天經驗是如何對人類嗅覺產生影響的。
"It's both exciting and disturbing," said Don Wilson of the New York University School of Medicine, a neurobiologist who was not involved in the work."It doesn't fit in with what I think or a lot of other researchers think about smell."
“此事既讓人感到興奮又讓人感到疑惑。”從事該項研究工作的紐約大學醫學院神經生物學家Don Wilson說，“這樣的結果與包括我在內的許多專家們對嗅覺的認識相抵觸。”
Instead of the brain processing all scent information, for instance, it seems nasal neurons preprocess some of it—almost as if the nose has its own small brain.
譬如在處理嗅覺信息時，并不是所有的工作都由大腦來承擔。鼻神經元似乎也承擔了部分工作——鼻腔好象自己有自己的小腦一樣。
◆Taking One in the Nose專一的嗅覺感知能力
The human nose contains a postage stamp-size smelling organ, called the olfactory epithelium, at the roof of the nasal cavity.
人類鼻腔的屋頂，有一塊面積如郵票大小被稱之為“嗅上皮”的嗅覺器官。
By probing mouse noses to measure the firing of nasal neurons, scientists had previously discovered that scent receptors might be organized into groups, similar to the way the tongue has zones armed to detect specific tastes such as sour, sweet, and salty.
科學家們通過對以往大鼠鼻腔神經元活動所做的測定實驗發現，嗅覺受體有可能存在著嗅覺功能上的分工。其分工方式如同舌部，酸、甜、咸各種味道均有各自的感知區域。
But a rodent's nose has more than 1,200 different types of scent receptors, and even a tiny probe could touch tens of thousands of receptors in one reading, making it hard to get a clear signal.
然而，大鼠鼻腔內有1200多種嗅覺受體。探測器的頂端盡管比針尖還要細，但每次測到的是數以萬計受體神經活動的信息，單個的信號無法辨別。
Humans have roughly 400 different kinds of receptors, however, making the business of sticking probes in noses and plucking out useful information more fruitful.
然而，人類鼻腔內約有400多種不同的嗅覺受體，能更有效地執行探測與識別有用信息的任務。
◆How the Nose Knows氣味是如何分辨的
A team led by neuroscientist Noam Sobel, of the Weizmann Institute of Science in Israel, asked more than 80 people to sniff substances with odors known to be either pleasant or unpleasant across many cultures.
由以色列魏茨曼科學研究所神經學家Noam Sobel領銜的研究小組，要求80余名具有不同文化背景的被試識別各種已知氣味的好壞。
Ordinary smells can be made up of tens to hundreds of compounds, so Sobel and his colleagues puffed only pure chemicals into the noses of their wired subjects, one scent at a time.
普通氣味是由數十或數百種物質所構成的，因此，Sobel和他的同事每次向聯有探測針的受試者的鼻腔內噴入的是純凈物，每次只感知一種氣味。
Pooling together 801 neural recordings from people's noses, the team found that some regions of the epithelium are better at detecting scent than other regions. The researchers also found hot spots that are better at interpreting either pleasantness or unpleasantness.
從對人體鼻腔收集到的801項神經活動記錄來看，小組人員發現某些區域的嗅上皮細胞比其它區域的對某種氣味更具感知能力。研究人員還發現能更好地識別氣味好壞的特定區域。
"To my surprise, this means something about the epithelium is tuned to pick up certain information" in certain zones, New York University's Wilson said."We don't understand what the purposes of those zones are," he added, "but that's exciting."
紐約大學的Wilson說，“真沒想到，嗅覺上皮是一種檢測特定嗅覺信息的結構。雖然這些區域的詳細功能還未查明，但這一結果是值得令人興奮的了。”
The smelling study was published online last week in the journal Nature Neuroscience.
有關研究成果發布于上周網絡版的《自然神經科學》雜志。
相關閱讀：科學家質疑「味覺分布圖」
原文鏈接：Secrets of Smell: Different Nose Parts for Stinky, Sweet
