3月28日的《科学》（Science）杂志报道说，当选择错误的气味会导致一种令人不适的电击时，人们的嗅觉会变得异乎寻常地敏感。这些发现提示，情感经验可以影响我们的感官知觉并且可能对我们学会如何躲避危险有着重要的影响。对调试作用的大多数研究一直集中在生物体是如何学习对感觉信号本身进行反应的，但Wen Li及其同事希望研究这种学习的过程是否会实际更改对信号本身的感知。
他们让自愿受试者嗅闻配对的气味，而这些气味是以“对映体的”形式存在的，即每种气味分子在结构上是相同的，但却互为镜像。这些对映体在正常情况下气味是相同的。自愿者对一组3个瓶子中的物质气味进行嗅闻，其中2个瓶子中含有的是相同的一种物质，而第3个瓶子中含有的是前2个瓶子中气味分子的对映体。起先，自愿者不能够辨认出那种单独的对映体气味。接着，这些自愿者经过了一个调试期。在此期间，他们在嗅闻一种气味的时候会受到一种轻度的电击，但在嗅闻其对映体气味的时候却不会受到电击。当重新进行测试的时候，这些受试者辨识出那种单独气味的能力得到了改善。
文章的作者还对自愿者辨识变化的脑部活动进行了监测，这些脑部活动的变化指的是在自愿者嗅觉变得更为敏锐的时候其嗅觉皮层活动模式出现的变化。在文章结尾处，作者推测在某些焦虑性的疾病中，患者区分真正发出危险信号的刺激与类似但不那么重要的刺激的能力可能受到了损害。（来源：EurekAlert!中文版）
生物谷推荐原始出处：
（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.
