RESUMO
BACKGROUND AND OBJECTIVES: For centuries, fragrance had beneficial psychological and physiological effects on humans. Aromatherapy, the use of concentrated essential oils extracted from herbs, flowers, and other parts of plants to treat various diseases, is becoming more commonly accepted within the health service. However, there are very few published articles, which provide a sound rationale for the use of aromatherapy as a medical intervention. The purpose of this study was to find a scientific explanation for the effect of aromatherapy by investigating 1. whether or not essential aroma oils caused increased brain activity and 2. which areas of the brain were activated by the essential aroma oils. MATERIALS AND METHODS: Olfactory fMRI (functional magnetic resonance imaging), which is capable of monitoring and recording regional pathophysiological fluctuations in living brains, was performed on 11 healthy adult humans during exposure to essential aroma oils (lavender and lemon oils) and buthanol. The c-fos immunohistochemical staining was also performed on brain tissues of 24 Mongolian gerbils after exposure to the essential aroma oils. RESULTS: In the human fMRI study, the olfactory cortex was activated in all subjects by the essential aroma oils and buthanol. Additionally, lavender oil also activated the hearing and language-related regions of brain. In the animal study, similar results were observed: immunoreactive cells were detected in the hearing and language related regions of gerbil brains that had been exposed to lavender oil. CONCLUSION: The lavender oil activated not only the olfactory region but also the hearing and language-related regions of the brain. These results imply that the essential aroma oil introduced through the olfactory pathway has effects on other regions of the brain.