Dec. 19, 2006 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 keep 24-hour time and are normally highly sychronized to
each other and environmental cycles of day-night. "It's been a
question for some time whether the SCN functions as the only
biological clock," said Herzog. "One wouldn't think that the
ability to smell would cycle, b