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否在右鼻孔或左鼻孔和大脑半球中具有与听觉功能类似的优势，使用两个37通道SQUID系统（Magne ®，Bti Co.）在所有参与者中记录对令人愉快的气味（草莓香精）和令人不愉快的气味（异戊酸）的脑磁图（MEG）60秒<TM>。通过目视检查拒收被伪影污染的MEG。研究了MEG显示低水平伪影的7名受试者。用离散傅立叶变换分析方法，计算了嗅刺激时左右半球脑磁图θ、α 1、α 2、β和γ频段的功率谱密度，并计算了嗅刺激时左右半球脑磁图θ、α 1、α 2、β和γ频段的功率谱密度。而α2频段在右半球表现为优势。然而，在左半球刺激期间，在任何频带的功率谱密度中，在左右半球之间没有观察到差异。对于难闻的气味，θ、α1和β频段的功率谱密度在右半球对左半球刺激的反应中表现出优势。结果表明，无论气味是令人愉快的还是令人不愉快的，右半球的嗅觉功能都占主导地位。然而，目前还不清楚为什么右鼻孔对愉快的气味更敏感，而左鼻孔对不愉快的气味更敏感。

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.