Human olfactory contrast changes during the menstrual cycle

Several lines of studies have reported that olfactory perception is influenced by physical and hormonal conditions. In the present study, we investigated changes of olfactory perception during the menstrual cycle of the human. Cyclopentadecanolide vapor was used and its perception intensity was measured by 6-point category scale methods. We especially focused on a novel concept termed "olfactory contrast" that has been just very recently derived from the patch clamp experiment that uses the solitary olfactory receptor cell. The results obtained from 18 trials (15 subjects) showed that olfactory contrast was significantly enhanced at the ovulatory and/or menstrual phases. It is suggested that olfactory contrast, which we defined as a new parameter, provides a useful tool in many kinds of studies exploring the olfactory perceived ability.