BackgroundAtypical responsiveness to olfactory stimuli has been reported as the strongest predictor of social impairment in children with autism spectrum disorders (ASD). However, previous laboratory-based sensory psychophysical studies that have aimed to investigate olfactory sensitivity in children with ASD have produced inconsistent results. The methodology of these studies is limited by several factors, and more sophisticated approaches are required to produce consistent results.MethodsWe measured olfactory detection thresholds in children with ASD and typical development (TD) using a pulse ejection system—a newly developed methodology designed to resolve problems encountered in previous studies. The two odorants used as stimuli were isoamyl acetate and allyl caproate.ResultsForty-three participants took part in this study: 23 (6 females, 17 males) children with ASD and 20 with TD (6 females, 14 males). Olfactory detection thresholds of children with ASD were significantly higher than those of TD children with both isoamyl acetate (2.85 ± 0.28 vs 1.57 ± 0.15; p < 0.001) and allyl caproate ( 3.30 ± 0.23 vs 1.17 ± 0.08; p < 0.001).ConclusionsWe found impaired olfactory detection thresholds in children with ASD. Our results contribute to a better understanding of the olfactory abnormalities that children with ASD experience. Considering the role and effect that odors play in our daily lives, insensitivity to some odorants might have a tremendous impact on children with ASD. Future studies of olfactory processing in ASD may reveal important links between brain function, clinically relevant behavior, and treatment.

Olfaction has recently been gaining attention in information and communication technology, as shown by attempts in theaters to screen videos while emitting scents. However, because there is no current infrastructure to communicate and synchronize odor information with visual information, people cannot enjoy this experience at home. Therefore, we have constructed a system of smell videos which could be applied to television (TV), allowing viewers to experience scents while watching their videos. To solve the abovementioned technical problems, we propose using the existing system for broadcasting closed caption. Our system's implementation is mindful of both video viewers and producers, allowing the system on the viewer end to disperse odorants in synchronization with videos, and allowing producers to add odor information to videos. We finally verify the system's feasibility. We expect that this study will make smell videos become common, and people will enjoy ones in daily life in the near future.

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Periodic assessment of olfaction is important because a decline in olfaction can be caused by disorders such as Alzheimer's dementia at an early stage. However, current olfactory tests are rarely conducted due to the time and effort necessary for the scent presentation and the problem of scent lingering in the air. Therefore, we developed an olfactory display using pulse ejection for medical use. We also developed several types of nozzles and compared them. We evaluated the performance of the olfactory display on patients with olfactory disturbance. Then, we measured the degree of olfactory loss of the patients by using T&T olfactometer, the most widely known olfactory test in Japan, and found that our olfactory display could accurately assess the olfactory skills of the patients. In the future, we aim to solve the problems of current olfactory tests by using the olfactory display and familiarize olfactory tests.