Monday, July 15, 2013
Your Brain’s Biological Clock, 2
Researchers have discovered that your daily rhythms of sleep and metabolism are driven by a biological clock in the suprachiasmatic nucleus (SCN), a structure in the brain made up of 20,000 neurons, all of which can keep daily (circadian) time individually. Eric Herzog’s lab has discovered a push-pull system in the SCN that allows the neurons to both synchronize precisely with one another and adjust their rhythms to those of the environment. “We think the neurotransmitter network is there to introduce enough jitter into the system to allow the neurons to resynchronize when environmental cues change, as they do with the seasons,” Herzog says. “But . . . it doesn’t introduce enough jitter to allow us to adjust quickly to the extreme time shifts of modern life, such as flying ‘backward’ (east) through several time zones.” Obviously, understanding the push-pull system in the SCN has enormous implications for public health, bearing, as it does, on daylight saving times, shift work, school starting times, medical intern schedules, truck driver hours, and many other issues where the clock in the brain is pitted against the clock in the hand.