3月28日的《科學(xué)》（Science）雜志報道說,，當(dāng)選擇錯誤的氣味會導(dǎo)致一種令人不適的電擊時,，人們的嗅覺會變得異乎尋常地敏感。這些發(fā)現(xiàn)提示,，情感經(jīng)驗可以影響我們的感官知覺并且可能對我們學(xué)會如何躲避危險有著重要的影響,。對調(diào)試作用的大多數(shù)研究一直集中在生物體是如何學(xué)習(xí)對感覺信號本身進(jìn)行反應(yīng)的，但Wen Li及其同事希望研究這種學(xué)習(xí)的過程是否會實際更改對信號本身的感知,。
他們讓自愿受試者嗅聞配對的氣味,，而這些氣味是以“對映體的”形式存在的，即每種氣味分子在結(jié)構(gòu)上是相同的,，但卻互為鏡像,。這些對映體在正常情況下氣味是相同的。自愿者對一組3個瓶子中的物質(zhì)氣味進(jìn)行嗅聞，其中2個瓶子中含有的是相同的一種物質(zhì),，而第3個瓶子中含有的是前2個瓶子中氣味分子的對映體,。起先，自愿者不能夠辨認(rèn)出那種單獨的對映體氣味,。接著,，這些自愿者經(jīng)過了一個調(diào)試期。在此期間,，他們在嗅聞一種氣味的時候會受到一種輕度的電擊,，但在嗅聞其對映體氣味的時候卻不會受到電擊。當(dāng)重新進(jìn)行測試的時候,，這些受試者辨識出那種單獨氣味的能力得到了改善,。
文章的作者還對自愿者辨識變化的腦部活動進(jìn)行了監(jiān)測，這些腦部活動的變化指的是在自愿者嗅覺變得更為敏銳的時候其嗅覺皮層活動模式出現(xiàn)的變化,。在文章結(jié)尾處,，作者推測在某些焦慮性的疾病中，患者區(qū)分真正發(fā)出危險信號的刺激與類似但不那么重要的刺激的能力可能受到了損害,。（來源：EurekAlert!中文版）
生物谷推薦原始出處：
（Science）,，Vol. 319. no. 5871, pp. 1842 - 1845，Wen Li,，Jay A. Gottfried
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.
