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Objective In the United States and European countries, the University of Pennsylvania Smell Identification Test (UPSIT), the Quick Smell Identification Test (Q-SIT), a shorter version of the UPSIT, and “Sniffin’ Sticks” are widely used for testing olfaction. The odor stick identification test for Japanese (OSIT-J) has been manufactured in Japan. This was followed by the development of “Open Essence,” consisting of cards that make use of sealed odorants. This study examined the usefulness of Open Essence in young volunteers with normal olfaction. Method The participants were 176 medical students in their clinical clerkships at the Department of Otolaryngology, Kochi Medical School Hospital. There were 111 males and 65 females, with a median age of 24 years (range 22–42 years). The olfactory function of all participants was confirmed as normal by screening with T&T olfactometry. Before beginning Open Essence, the subjects were asked to answer a questionnaire on their olfaction and habits. Results Females had significantly better smell identification than males. Of the 12 odorants, “perfume” and “cooking gas” were difficult to identify, because perfume involves different imagery and the compounds that give the smell of gas are readily volatilized. In contrast, all participants recognized “curry” and “menthol,” probably because they are received as both somatosensory stimuli and smell. Conclusions These results suggest that, with improvement, Open Essence might be used for testing olfaction in Japanese subjects.

Objective To investigate the differences in regions of brain activation in response to olfactory stimulation by functional magnetic resonance imaging in conditions of prior warning of an odor and without. Methods Participants were 17 normal right-handed volunteers; 8 participants received prior warning of the odor (informed condition) and 9 participants were not pre-warned (naive condition). The odorant used was isovaleric acid. Results In the informed condition with prior warning, activation was observed in the putamen extending to the insula, amygdala, and inferior frontal gyrus, and there was instant reification of the odor, while in the naive condition without prior warning, activation was observed in the anterior cingulate cortex, entorhinal cortex, putamen and inferior frontal gyrus, and recognition of the odor was difficult. Conclusions These results suggest that the condition prior to olfactory stimulation, i.e., with or without prior warning, can affect recognition and regions of brain activation in response to olfactory stimulation using isovaleric acid. Differences in recognition and regions of brain activation between both conditions could be associated with response latencies, or degree of attention, expectation and/or concentration.