Biologists at Washington University in St. Louis have discovered a large biological clock in the smelling center of mice brains and have revealed that the sense of smell for mice is stronger at night, peaking in evening hours and waning during day light hours.
A team led by Erik Herzog, Ph.D., Washington University associate professor of Biology in Arts & Sciences, discovered the clock in the olfactory bulb, the brain center that aids the mouse in detecting odors.
The olfaction biological clock is hundreds of times larger than the known biological clock called the suprachiasmatic nucleus (SCN), located at the base of the brain right on top of where the optic nerves cross each other. Cells in both the SCN and the olfactory bulb to each other and environmental cycles of day-night.
"Its been a question for some time whether the SCN functions as the only biological clock," said Herzog. "One wouldnt think that the ability to smell would cycle, but thats what we show."
"I think now that the SCN is like the atomic clock, important for keeping central time, and then there are all of these peripheral clocks for timing tasks like sleep-wake, vigilance, digestion, olfaction, hearing, touch and vision, though not all yet found. It may be that the peripheral clocks are like individual wristwatches that we must periodically reset."
Perhaps most surprising is the observation that the olfactory bulb clock can run independent of daily rhythms in sleep-wake or the SCN, making it the Big Ben of the mammalian circadian rhythm world.
"It seems to be one of those biological clocks that can keep running itself for a long time, even without the SCN," Herzog said.
Results were published in the Nov. 22, 2006, issue of the Journal of Neuroscience.
Herzog and collaborators Daniel Granados-Fuentes, Ph.D., Washington University postdoctoral researcher, and undergraduate student researcher Alan Tseng, put a little cedar oil on a Q-tip an
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Contact: Tony Fitzpatrick
tonyy_fitzpatrick@wustl.edu
314-935-5272
Washington University in St. Louis
18-Dec-2006