Kim Yeon-Kyu, Watanuki Shigeki
Department of Human Living System Design, Kyushu University, Fukuoka, Japan.
J Physiol Anthropol Appl Human Sci. 2003 Nov;22(6):285-91. doi: 10.2114/jpa.22.285.
More than sensory stimuli, odorous stimuli were employed to facilitate the evocation of emotional responses in the present study. The odor-stimulated emotion was evaluated by investigating specific features of encephalographic (EEG) responses produced thereof. In this study, the concentrations of the same odor were altered; viz., the changes in odor-induced emotional level were compared with the concurrently monitored EEG response features. In addition, we performed the mental task to evoke the arousal state of the brain and investigated the resemblance of response characteristics of the resting state to the post-mental task resting state. Subjects having no abnormalities in the sense of smell included 12 male undergraduate and graduate students (age range: 22-26 years). Experiment I involved 2 types of odors that induced favorable odorous stimuli (pleasant induction); test-solutions were either diluted 150 (easily perceptible odorous sensation) or 500 (slightly perceptible odorous stimuli) times. Experiment II had 2 types of odors that evoked unfavorable odorous stimuli (unpleasant induction), and test-solutions with dilution rates similar to those of pleasant induction were prepared. Odorless distilled water was used as the control in both experiments. From results of rating the odorous stimuli of our compounds used, the candidates were respectively found to be appropriate in inducing the pleasant and unpleasant smell sensations. The analyses of EEG responses on inducing pleasant and unpleasant smell sensations revealed that the EEG activities of the left frontal region were enhanced. This finding may establish the hypothesis of a relationship prevailing between the positive approach-related emotion evoked by the visual sensation and the left hemisphere (Davidson, 1992; Tomarken et al., 1989). In other words, it can be interpreted that the negative withdrawal-related emotion may be associated with activities of the right hemisphere. However, this hypothesis may not be applicable to the unpleasant odors, as the unpleasant emotions are activated by the unpleasant odors not only in the bilateral frontal regions but also over an extensive area of the brain. As such, the pleasant emotions are evoked in the left frontal brain region while the unpleasant emotions are incited in the bilateral frontal and extensive regions in the brain with the odorous stimuli. Moreover, intrinsic EEG activities in response to the pleasant and unpleasant inputs were not observed after performing the mental tasks. In other words, EEG responses reflecting central nervous system activities elevated by loading of the mental tasks as a result of exposure to the pleasant and unpleasant odors may not apparently be observed.
在本研究中，为了促进情绪反应的诱发，采用的是气味刺激而非感觉刺激。通过研究由此产生的脑电图（EEG）反应的特定特征来评估气味刺激引发的情绪。在本研究中，改变了相同气味的浓度；即，将气味诱发的情绪水平变化与同时监测的EEG反应特征进行比较。此外，我们进行了心理任务以唤起大脑的唤醒状态，并研究静息状态与心理任务后静息状态的反应特征的相似性。嗅觉无异常的受试者包括12名男性本科生和研究生（年龄范围：22 - 26岁）。实验I涉及2种能诱发良好气味刺激（愉快诱导）的气味；测试溶液分别稀释150倍（易于察觉的气味感觉）或500倍（轻微可察觉的气味刺激）。实验II有2种能诱发不良气味刺激（不愉快诱导）的气味，并制备了与愉快诱导稀释率相似的测试溶液。在两个实验中均使用无味蒸馏水作为对照。从对我们所使用化合物的气味刺激进行评分的结果来看，分别发现这些候选物适合诱发愉快和不愉快的嗅觉感受。对诱发愉快和不愉快嗅觉感受的EEG反应分析表明，左额叶区域的EEG活动增强。这一发现可能确立了视觉感受诱发的与积极趋近相关情绪和左半球之间普遍存在的关系的假设（戴维森，1992；托马肯等人，1989）。换句话说，可以解释为与消极退缩相关的情绪可能与右半球的活动有关。然而，这一假设可能不适用于不愉快的气味，因为不愉快的气味不仅在双侧额叶区域，而且在大脑的广泛区域激活不愉快情绪。因此，气味刺激时，愉快情绪在左额叶脑区诱发，而不愉快情绪在大脑的双侧额叶和广泛区域诱发。此外，在执行心理任务后，未观察到对愉快和不愉快输入的内在EEG活动。换句话说，可能无法明显观察到因接触愉快和不愉快气味而导致心理任务负荷增加所反映的中枢神经系统活动的EEG反应。
