"We then preserved their brains and counted the number of olfactory bulb cells that had been activated by the odorant," Herzog said. "The gene cFOS is a marker for cells that were activated by the stimulus. We recorded the expression of that gene. All of the data came from in vivo measurements." They saw more of those cells light up in the olfactory bulb at night than in the day.
"The olfactory bulb might be more sensitive at night when the creatures are active than when they are resting in the day," Herzog speculated. "This might help them find food or mates when they are hungry for food or for love."
Do the results suggest that women should splash on the Estee Lauder during the night so that men can notice all the more and shun the bottle during the day" "There are anecdotes in the literature about humans liking certain perfumes more during the evening than the morning, and there is some evidence that we also have daily rhythms in olfaction," Herzog said.
Herzog said that it is rare to find someone missing their SCN, so its tricky to study the human olfactory clock by itself. For this reason, his lab plans to study olfactory behavior in mice.
"We can say that this (olfactory bulb) clock has a functional consequence, and now were setting up to do olfactory behavior," he said. "Well ask the mice to tell us when they can smell odors of different concentrations, and we hope to learn more about how and how much the clock modulates their sense of smell, and which cells and genes are needed.
The olfactory bulb biological clock study opens up many questions, a key one of which is: Why are there multiple clocks?
"This idea of multiple biological clocks is new," Herzog said. "We might need now to consider ourselves a clock shop. It appears that disrupting the coordination between these clocks is bad for our health, like in jet lag or shift work."