生物谷報(bào)道：你或許聽(tīng)說(shuō)過(guò),，一些人的鼻子有感知危險(xiǎn)的特異功能,。美國(guó)西北大學(xué)（Northwestern University, 生物谷注）最新研究表明,，人類的鼻子確實(shí)能嗅出危險(xiǎn),。人的大腦嗅覺(jué)區(qū)能建立糟糕經(jīng)歷與當(dāng)時(shí)氣味間的聯(lián)系,。因此當(dāng)麻煩或危險(xiǎn)再次臨近時(shí),，鼻子能立刻聞出這種氣味,，并發(fā)出避開(kāi)危險(xiǎn)的“警報(bào)”。

西北大學(xué)研究人員通過(guò)一項(xiàng)實(shí)驗(yàn),，證明鼻子與危險(xiǎn)有不可思議的聯(lián)系,。當(dāng)實(shí)驗(yàn)志愿者聞特定氣味時(shí)，研究人員以輕微電擊刺激他們,，使他們的大腦嗅覺(jué)區(qū)“記住”這種氣味,。

核磁共振檢查結(jié)果顯示，志愿者接受輕微電擊后,，大腦嗅覺(jué)區(qū)記憶氣味功能得到提高,。大腦神經(jīng)“牢記”電擊與氣味間的聯(lián)系，因此能更迅速區(qū)分兩種相似氣味,。換言之,，人類大腦能建立嗅出危險(xiǎn)的機(jī)制。

研究人員說(shuō),，這項(xiàng)實(shí)驗(yàn)解釋了人類能感知危險(xiǎn)迫近的原因,。史前人類擁有區(qū)別不同動(dòng)物氣味的能力，正是在惡劣環(huán)境中為生存而進(jìn)化發(fā)展的結(jié)果,。

科學(xué)家早已發(fā)現(xiàn),，人類嗅覺(jué)與情緒之間有緊密聯(lián)系。香水味或蛋糕的甜香味能讓人回憶起美好往事,。相反,，機(jī)油氣味則可能使患有“創(chuàng)傷后應(yīng)激障礙”的士兵想起戰(zhàn)場(chǎng)上的痛苦經(jīng)歷。

研究人員說(shuō),，經(jīng)歷過(guò)廚房火災(zāi)的人聞到煙味時(shí),，能立即區(qū)分是東西燒糊的氣味還是普通煙味,。

因此，當(dāng)人們被環(huán)境中的各種信息包圍時(shí),，擁有嗅出危險(xiǎn)的能力可以幫助人們敏銳察覺(jué)危險(xiǎn)的臨近,。

這項(xiàng)成果刊登在美國(guó)3月28日的《科學(xué)》雜志上。

生物谷推薦原始出處：

Science 28 March 2008:
Vol. 319. no. 5871, pp. 1842 - 1845
DOI: 10.1126/science.1152837

Aversive Learning Enhances Perceptual and Cortical Discrimination of Indiscriminable Odor Cues
Wen Li,1* James D. Howard,1 Todd B. Parrish,1,2 Jay A. Gottfried1,3,4

Learning to associate sensory cues with threats is critical for minimizing aversive experience. The ecological benefit of associative learning relies on accurate perception of predictive cues, but how aversive learning enhances perceptual acuity of sensory signals, particularly in humans, is unclear. We combined multivariate functional magnetic resonance imaging with olfactory psychophysics to show that initially indistinguishable odor enantiomers (mirror-image molecules) become discriminable after aversive conditioning, paralleling the spatial divergence of ensemble activity patterns in primary olfactory (piriform) cortex. Our findings indicate that aversive learning induces piriform plasticity with corresponding gains in odor enantiomer discrimination, underscoring the capacity of fear conditioning to update perceptual representation of predictive cues, over and above its well-recognized role in the acquisition of conditioned responses. That completely indiscriminable sensations can be transformed into discriminable percepts further accentuates the potency of associative learning to enhance sensory cue perception and support adaptive behavior.

1 Cognitive Neurology and Alzheimer's Disease Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
2 Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
3 Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
4 Department of Psychology, Northwestern University, Evanston, IL 60208, USA.

* To whom correspondence should be addressed. E-mail: [email protected] .