‘Reset’ button for the body clock discovered

Researchers from Vanderbilt University in Nashville, Tennessee, USA used optical fiber and lasers to reset the circadian clocks in mice.

The study’s findings, published in Nature Neuroscience, demonstrated that stimulating and suppressing particular neurons in mice – in a way that emulates their day and night activity levels – can act as a reset button for the circadian clock.

“We found we can change an animal’s sleep/wake rhythms by artificially stimulating the neurons in the master biological clock,” says the director of the study, Douglas McMahon of Vanderbilt University.

To achieve the clock reset, the research team used optogenetics on mice to manipulate the firing rate of Suprachiasmatic Nucleus (SCN) neurons, which are responsible for regulating the sleep-wake cycle in our bodies. This is the same technique that has been used recently in the discovery of the on/off switch for thirst and overeating, which we reported on last month.

The circadian clock is the body’s internal clock that controls when we feel sleepy and when we are most alert. Certain environmental or health conditions, such as working the night shift, or travelling across time zones can affect the rhythm of the clock.

According to the team of neuroscientists, mice have a nearly-identical biological clock to humans, with the key difference being that a mouse’s circadian clock is tuned for a nocturnal lifestyle.

By manipulating the circadian clocks of mice, we may be able to imitate the process in humans in order to reset the human biological clock. This would allow neuroscientists to develop ways to combat jetlag as well as new treatments for conditions like seasonal affective disorder, and reduce the adverse health effects of working the night shift.

The SCN firing rate was thought to be solely an output of circadian rhythmicity (which is the 24 hour physiological clock of all living things), but this study reveals that it is actually a key component of the cycle. “[It] shows that we still have a lot to learn about how our biological clocks work,” McMahon explained.