Spectral analysis of changes in electroencephalographic activity after the chewing of gum.

The present study aimed to examine the psychosomatic effect in the chewing of marketed gum using electroencephalogram (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 (post-chewing 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 post-chewing 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.