Enhancement of electroencephalogram activity in the theta-band range during unmatched olfactory-taste stimulation

  • Saori Maeda
  • Hiroshi YoshimuraEmail author
Original Paper


The aim of this study was to investigate how odor stimulation affects taste perception. Electroencephalogram (EEG) signals were measured from the frontal region of the head in normal, healthy subjects, and frequency analyses were performed. Each odor stimulation was delivered while the subject was tasting chocolate, using chocolate paste as the odorant for ‘matched odor stimulation,’ and garlic paste for ‘unmatched odor stimulation.’ Differences in EEG signals appeared between the matched and unmatched arms of the study. Comparison of the frequencies of EEGs captured under the condition of unmatched odor stimulation with those captured under the condition of matched odor stimulation showed that the occupancy rate of the theta-frequency band under the condition of unmatched odor stimulation was higher than that under the condition of matched odor stimulation. Interestingly, a negative correlation existed between the occupancy rate of the theta-frequency band and the subjective feeling of chocolate sweetness. The present findings suggest that when humans receive odors that do not match with the foods being consumed, subjective feelings are disturbed and theta-band brain activity is increased while the unmatched information is cross-checked.


Electroencephalogram Fast Fourier Transform analysis Smell Taste Theta 



We wish to thank Dr. T. Akamatsu, T. Hasegawa, C. Yao, H. Y. Miyachi; Kanayama for experimental assistance. This study was partially supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant-in-Aid for Scientific Research C 22590966), and was partially supported by the Research Clusters Program of Tokushima University.

Author contribution

HY contributed to the experimental design of the research, and drafted the manuscript. SM and HY performed experiments, and analyzed and interpreted the data.

Compliance with ethical standards

Conflict of interest

The authors have no conflicts of interest to declare.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© The Physiological Society of Japan and Springer Japan KK, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Molecular Oral Physiology, Institute of Biomedical SciencesThe Tokushima University Graduate SchoolTokushimaJapan
  2. 2.Department of Oral Health Sciences, Faculty of Nursing and Health CareBAIKA Women’s UniversityOsakaJapan

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