Chemical Senses Vol. 30 No. suppl 1 © Oxford University
Press 2005; all rights reserved
Prevention and/or Recovery Effects by Green Odor(s) on Fatigue and Green-odor-responsible Brain Regions as Revealed by PET
1 Department of Physiology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan, 2 Department of Oral Physiology, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan, 3 Department of Health Sciences, Kansai University of Welfare Sciences, Osaka 582-0026, Japan, 4 Soda Aromatic Co. Ltd, Tokyo 103-0023, Japan, 5 Department of Applied Biological Chemistry, Yamaguchi University, Yamaguchi 753-8511, Japan, 6 Central Research Laboratory, Hamamatsu Photonics, K.K., Shizuoka 434-8061, Japan and 7 Department of Psychology, Tokyo Metropolitan Institute of Neuroscience, Tokyo 183-8526, Japan
Correspondence to be sent to: Yasuyoshi Watanabe, e-mail: yywata{at}med.osaka-cu.ac.jp
Key words: anterior cingulate, anti-fatigue effect, functional neuroimaging, green odor, olfaction, PET
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Introduction |
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 Top Introduction Anti-fatigue effects of green...Activation of the anterior...AcknowledgementsReferences |
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Green odor (we used a mixture of 3Z-hexenol and 2E-hexenal in this study) has many physiological functions. Stress-induced hyperthermia was attenuated by green odor in rats (Akutsu et al., 2002
).
Sano et al. (2002) reported
that a mixture of hexenol and hexenal was accepted as a pleasant odor and it decreased
the amplitude of an event-related potential (P300). However, the neural mechanisms of the
effect of hexenol and hexenal are almost completely unknown. We studied its effect on
prevention and/or recovery from fatigue, through analyzing the behavioral performance
(reaction time, RT) of monkeys during repetition of a simple visual discrimination task
and the autonomic function as judged by acceleration plethysmography (APG) during a
mental task [advanced trail making test (ATMT), continuously loaded for 4 h] in
human volunteers. Moreover, we investigated changes in regional cerebral blood flow
(rCBF) during green-odor stimulation using positron emission tomography (PET) in
monkeys. |
Anti-fatigue effects of green odor |
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TopIntroductionAnti-fatigue effects of green...Activation of the anterior...AcknowledgementsReferences |
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Exposure of monkeys to green odor throughout the tasking period resulted in a reduction of delay of RT during the task. In the human study, the RT of ATMT just after the start and before the end of a task in the control group was delayed (P < 0.05). The height of the wave A of APG decreased by 0.36 times (P < 0.005) in a comparison between before and after ATMT. On the other hand, the RT in the group that inhaled green odor had little delay throughout the task. The wave A decreased by 0.77 times (P < 0.05) after the task. This reduction in the green odor group showed a significant difference as compared with the control group (P < 0.05). In conclusion, ‘green odor’ has fatigue-mitigation effects in monkeys and humans; this effect might be via an autonomic function, such as a healing effect on the sympathetic nervous system.
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Activation of the anterior cingulated gyrus by green odor: a monkey PET study |
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TopIntroductionAnti-fatigue effects of green...Activation of the anterior...AcknowledgementsReferences |
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Functional neuroimaging using PET makes it possible to localize functional brain regions in humans and primates brains by detecting changes in regional cerebral blood flow (rCBF). Performing PET studies in monkeys and humans will aid in integrating the electrophysiological studies in monkeys. We have examined changes in rCBF during olfactory stimulation using PET in alert monkeys (Kobayashi et al., 2002
). Olfactory stimulation by
acetic acid or apple odor increased rCBF in the prepyriform area, substantia innominata
and amygdala. Apple odor or flavor stimuli increased rCBF in the inferior occipital
gyrus, which is the visual area, in addition to the above areas. These findings suggest
that the increases in rCBF in response to neural activities in the primary olfactory
cortices are detectable by use of PET. In addition, the regions activated by apple
stimuli suggest that higher brain function, in this case perhaps visual imagery, might be
detected with PET in alert monkeys. The equivalent mixture of 0.03%
cis-3-hexenol and 0.03% trans-2-hexenal (hexenol/hexenal; Soda
Aromatic, Japan) diluted with triethyl citrate—‘green odor’—is
known to have a healing effect on psychological damage caused by stress. The behavioral
studies described above in humans and monkeys revealed that hexenol/hexenal prevents the
prolongation of reaction time caused by fatigue. In this study, we investigated which
brain regions are activated by the odor of hexenol/hexenal using PET with alert monkeys.
rCBF in the prepyriform area was commonly increased by passive application of odor:
acetic acid, iso-amylacetate, or hexenol/hexenal. We observed rCBF increases in
the orbitofrontal cortex (the secondary olfactory cortex) by these olfactory stimuli in
two of three monkeys and found no predominance of laterality of the activated hemisphere.
In addition to these olfactory-related regions, the anterior cingulate gyrus was
activated by the odor of hexenol/hexenal (Figure
1) (Sasabe et al., 2003). These findings suggest that
the increase in rCBF in the anterior cingulate gyrus causedby the odor of hexenol/hexenal
may contribute to its healing effects observed in the monkey.
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Acknowledgements |
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TopIntroductionAnti-fatigue effects of green...Activation of the anterior...AcknowledgementsReferences |
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This study was supported in part by the Special Coordination Funds of the Ministry of Education, Culture, Sports, Science and Technology, Japanese Government and by Research for the Future Program JSPS-RFTF 98L00201 from the Japan Society for the Promotion of Science to Y.W.
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References |
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TopIntroductionAnti-fatigue effects of green...Activation of the anterior...AcknowledgementsReferences |
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Akutsu, H., Kikusui, T., Takeuchi, Y., Sano, K., Hatanaka, A. and Mori, Y. (2002) Alleviating effects of plant-derived fragrances on stress-induced hyperthermia in rats. Physiol. Behav., 75, 355–360.[CrossRef][Medline]
Kobayashi, M., Sasabe, T., Takeda, M., Kondo, Y., Yoshikubo, S., Imamura, K., Onoe, H., Kogo, M., Matsuya, T., Morimoto, T., Sawada, T. and Watanabe, Y. (2002) Functional anatomy of olfactory and gustatory perception in the monkey revealed by positron emission tomography. Eur. J. Neurosci., 16, 975–980.[CrossRef][Web of Science][Medline]
Sano, K., Tsuda, Y., Sugano, H., Aou, S. and Hatanaka, A. (2002) Concentration effects of green odor on event-related potential (P300) and pleasantness. Chem. Senses, 27, 225–230.
Sasabe, T., Kobayashi, M., Kondo, Y., Onoe, H., Matsubara, S., Yamamoto, S., Tsukada, H., Onoe, K., Watabe, H., Iida, H., Kogo, M., Sano, K., Hatanaka, A., Sawada, T. and Watanabe, Y. (2003) Activation of the anterior cingulate gyrus by green odor: a monkey positron emission tomography study. Chem. Senses, 28, 565–572.
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