Chaotic analysis of EEG activities stimulated by pleasant odor and unpleasant odor

Some research groups have studied how to evaluate human olfaction objectively. But, there has been no attempt to evaluate objectively the subjective effects evoked by odor stimulation. Here, the authors tried to evaluate the subjective effects evoked by odor stimulation. In this study, they measured the EEG activity of a subject who was stimulated by an odor and evaluated objectively the influence of the odor stimulation by chaotic analysis and frequency analysis. It was considered that the effects of odor stimulation were measurable even if the subject wasn't conscious of the odor. The results showed that in the case of pleasant odor stimulation the chaotic value of EEG data decreased slowly with time, but unpleasant odor stimulation dispersed it.