Discrete Fourier transform analysis of nostril and cerebrum hemisphere dominance to pleasant and unpleasant odors as assessed by magnetoencephalography.

为了确定人类对气味的嗅觉功能是在右鼻孔还是左鼻孔和大脑半球占据主导地位，与听力功能相似，使用两个37通道SQUID系统（Magne^<TM>, Bti Co.）记录了所有参与者对令人愉快的气味（草莓香精）和令人不快的气味（异缬酸）的脑磁图（MEGs） 60秒。被人工制品污染的meg经目测不合格。研究人员对七名脑电信号显示低水平伪影的受试者进行了研究。采用离散傅立叶变换分析方法，计算了每个鼻孔在气味刺激时左右脑θ、α 1、α 2、β和γ频段的功率谱密度。当右鼻孔受到刺激时，θ、α1和α2频段的功率谱密度在右半球占优势。然而，在左鼻孔刺激期间，左右半球在任何频段的功率谱密度上都没有观察到差异。在左鼻孔刺激下，右侧脑半球的功率谱密度以θ、α1和β频段为主。右鼻孔刺激时左右脑各频段功率谱密度均无差异。这些结果表明，无论气味是令人愉快的还是令人不快的，嗅觉功能都在右半球占据主导地位。然而，目前还不清楚为什么右鼻孔对令人愉快的气味更敏感，而左鼻孔对令人不快的气味更敏感。

To determine whether human olfactory function to odors has dominance in the right or left nostrils and cerebrum hemispheres similar to hearing function, magnetoencephalograms (MEGs) to a pleasant odor (strawberry essence) and an unpleasant odor (isovalcric acid) were recorded for 60 seconds hi ll participants with use of two 37-channel SQUID systems (Magne^<TM>, Bti Co.). MEGs contaminated by artifacts were rejected by visual inspection. The seven subjects whose MEGs showed low levels of artifacts were studied. The power spectrum densities of the θ, α 1, α 2, β, and γ, frequency bands in the right and left hemispheres during odor stimulation of each nositril were calculated on the basis of a 50-second portion of the MEGs by means of discrete Fourier transform analysis.With the pleasant odor, the power spectrum densities of the θ, α1, and α2 frequency bands showed dominance in the right hemisphere during right-nostril stimulation. No difference, however, was observed between the right and left hemispheres in the power spectrum densities of any frequency band during left-nostril stimulation. With the unpleasant odor, the power spectrum densities of the θ, α1, and β frequency bands showed dominance in the right hemisphere in response to left-nostril stimulation. No difference was observed between the power spectrum densities of any frequency band between the right and left hemispheres during right-nostril stimulation.These results suggest that olfactory function had dominance in the right hemisphere regardless of whether the odor was pleasant or unpleasant. However, it remains unclear why the right nostril odor was more sensitive to the pleasant odor and the left nostril more sensitive to the unpleasant odor.