Introduction

Brain activation in response to olfactory stimuli has been studied using functional magnetic resonance imaging (fMRI), but there is little knowledge about processing repeated olfactory information which is usual in daily life.

Methods

This fMRI study was designed to investigate brain response to repeated odorant stimulation with positive and negative valences in 12 healthy right-handed volunteers. There was a 25-min rest interval between two fMRI runs with identical stimulation paradigms with two odors, as phenylethyl alcohol (PEA) and isovaleric acid (IVA), and the two odors were released alternately.

Results

There was a similar activation pattern in regions of primary and secondary olfactory cortex induced by odors of both valences, especially by negative odor. Weakened activation of the brain is responsive to repeated both pleasant and unpleasant smell. Nevertheless, the repeated unpleasant odor has a more intimate relationship with the piriform cortex, amygdala, and hippocampus.

Conclusion

We conclude that asymmetric brain activation in response to repeated odorant stimulation depended on valences and that the unpleasant odor can evoke more negative emotion and profound memory.

Implications

We explore the central processing about repeated olfactory information applied fMRI for the first time, revealing asymmetric brain activation in response to repeated odors of pleasantness and unpleasantness.

中文翻译：

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对重复的令人愉快和不愉快的气味做出不同的大脑激活反应

介绍

人们已经利用功能磁共振成像（fMRI）研究了大脑对嗅觉刺激的激活反应，但对处理日常生活中常见的重复嗅觉信息知之甚少。

方法

这项功能磁共振成像研究旨在调查 12 名健康的右手志愿者的大脑对重复正价和负价气味刺激的反应。两次 fMRI 运行之间有 25 分钟的休息间隔，具有相同的刺激范例，有两种气味，如苯乙醇 (PEA) 和异戊酸 (IVA)，并且两种气味交替释放。

结果

两种价态的气味（尤其是负气味）诱导的初级和次级嗅觉皮层区域存在相似的激活模式。大脑对重复的令人愉快和不愉快的气味的反应减弱。尽管如此，反复出现的难闻气味与梨状皮层、杏仁核和海马体有着更密切的关系。

结论

我们得出的结论是，对重复气味刺激的不对称大脑激活取决于化合价，并且令人不快的气味可以唤起更多的负面情绪和深刻的记忆。

影响

我们首次应用功能磁共振成像技术探索重复嗅觉信息的中枢处理过程，揭示了大脑对重复的愉快和不愉快气味的反应的不对称激活。