The objective of the present study was to evaluate the effect on the electroencephalogram (EEG) of a chewing gum with and without our prepared new flavor. Electroencephalograms were obtained after the following three tests: chewing pure gumbase with sucrose (standard gumbase), chewing flavored standard gum and the inhalation of flavored aromatic oil. As the control, we used the pre-stimulus control EEG record without a stimulus. We examined the relationship between the pre-stimulus control record and the post-stimulus record using the changes of power in four bands. Chewing the standard gumbase led to an increase in the alpha wave and a decrease in the beta wave. Chewing the flavored standard gum and inhaling the flavored aromatic oil each increased the alpha and beta waves. In addition, chewing the flavored standard gum led to a change in the ratio of theta wave in the frontal area. The difference in the theta, alpha and beta bands in chewing gum with and without the added flavor suggested that the flavor as well as chewing could induce concentration with a harmonious high arousal state in brain function.

The effects of three principal constituents (sugar, spearmint, and gumbase) in chewing gum on EEG findings in 20 normal subjects were investigated. After they chewed the gumbase, theta activity decreased significantly at Fp2, O1, T3, T4, F4, P3, and Pz; alpha activity increased significantly at O1 and decreased significantly at Fp1, and beta activity increased significantly at Fp1, Fp2, O1, T3, T4, P3 and Pz. After they inhaled the spearmint, alpha activity decreased significantly at 02, F3, P4, and Fz, and beta increased significantly at 02, F3, P4, and Fz. The mean frequency of the alpha band was significantly higher than after 1 min at rest without inhalation. After the subjects chewed the gumbase with sucrose, theta activity increased at Fp2 and Fz; alpha activity increased significantly at T3; and beta activity decreased significantly at Fpl, Fp2, F4, P3, P4, Fz, and Pz. The mean frequency of the alpha band was significantly lower than after 1 min at rest without it at almost all the positions. These results suggest that the gumbase with sucrose induced relaxed concentration effects while inhalation of spearmint induced arousal effects. The chewing of gumbase showed arousal tendency.

The present study aimed to examine the psychosomatic effect in the chewing of marketed gum using eletroencephalogram (EEG) as an index. The EEG were taken in two sets: (i) a resting period before chewing (control recording) and a resting record (post-resting recording) for examining reproducibility; and (ii) a control recording and resting period after gum-chewing for 3 min (postchewing recording). The ratio of each frequency band to the total frequency power, the mean frequency of the alpha band and laterality of the frequency power was calculated. In the examination of the reproducibility, no statistically significant differences were observed between control recording and post-resting recording in all indices. In the reflection of EEG after gum-chewing, there were no significant differences between control recording and the postchewing recording. However, a significant interaction was observed among these indices by analysis of variance. In addition, the alpha power in the post-chewing recording was significantly higher than that in the control recording at almost all the positions. In conclusion, the intra-individual reproducibility of EEG was confirmed in the recording method. Furthermore, it was suggested that a significant interaction and a rising trend of the mean frequency of the alpha band after gum-chewing reflected 'arousal' psychosomatic responses by the chewing of marketed gum.

We investigated brain activity in response to orofacial pain in 20 healthy subjects in order to characterize the relationship between pain and changes in brain function. First, the pressure pain threshold (PPT) at the styloid process of the temporal bone (Libman's point) of 20 subjects was measured by a pressure algometer. Second, electroencephalographic (EEG) changes of 20 subjects before and after 10 s of constant pressure stimulation at Libman's point were measured. These 20 subjects were divided into two groups: 10 subjects with higher PPT (high group) and 10 subjects with lower PPT (low group). EEG change in beta activity after stimulation was greater in the low group than the high group, and there was a significant negative correlation between this change and PPT, with even minor constant stimulation inducing larger EEG change in individuals highly receptive to pain. The present study demonstrated that a relative reduction in beta activity after pain stimulation was more remarkable in subjects with lower PPT than in subjects with higher PPT, and that this change was closely related to a hemispheric balance, with even minor constant stimulation inducing changes in brain waves in individuals highly sensitive to pain. Key wordselectroencephalography, hemispheric balance, pressure pain threshold, pressure stimulation, styloid process of the temporal bone.

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