“一朝被蛇咬，十年怕井绳”。研究人员发现，通常情况下，有创伤后压力症的人会不由自主地对无害刺激产生出类似于过去受伤害时的反应。比如，他们将中性声音与不愉快的结果联系起来，结果让他们更难区分相似声音间的差别。新成果发表在5月在线出版的《自然—神经科学》期刊上。
Rony Paz和同事让受试者聆听与某种气味配对的一种特定频率的音调。当这种气味令人愉悦时，受试者很容易从类似音调中区分出这种音调。然而，他们又发现，当一种音调与不愉快的气味联系起来时，受试者很难从类似音调中区分出这种音调。当研究人员将与音调配对的气味换为声音时，他们观察到了同样的现象，而且这种现象持续到训练结束后。（生物谷Bioon.com）
生物谷推荐原文：
Nature Neuroscience DOI:10.1038/nn.2802
Auditory aversive learning increases discrimination thresholds
Jennifer Resnik; Noam Sobel; Rony Paz
Animal studies of discriminative fear conditioning traditionally use stimuli that are distant in physical features and thus easily distinguished perceptually. Independently, human studies have shown that training mostly improves discrimination thresholds. We found that aversive learning actually induced an increase in discrimination thresholds in humans and that subjective aversion during conditioning predicted the individual threshold change. This counterintuitive performance deterioration occurred when using odors or sounds as aversive reinforcers and was not a result of attentional distraction or decision bias. In contrast, positive reinforcement or mere exposure induced the typically reported decrease in thresholds. Our findings indicate that aversive outcomes induce wider stimulus generalization by modulating perceptual thresholds, suggesting the engagement of low-level mechanisms. We suggest that for risk- or loss-related stimuli, less specificity could be a benefit, as it invokes the same mechanisms that respond quickly and efficiently in the face of danger.
