Washington, Sep 10 - Alexis Webb enters a small room painted dark green, turns off the lights and bends over a microscope over a black box to see a single nerve cell on a glass cover slip glowing dimly - indicating the isolated cell is busy keeping time.

Researchers at Washington University in St. Louis (WUSTL) have shown that isolated nerve cells like this one from the biological clock are capable of keeping time, but they do a better job when there are some 20,000 other neurons around.

The biological clock, a one-square mm area of the brain called the suprachiasmic nucleus, or SCN, just above the roof of the mouth and atop the crossing of the optic nerves, comprises about 20,000 neurons.

Webb, a graduate fellow in the neuroscience Ph.D. programme, working with Erik Herzog, associate professor of biology and others, has demonstrated that individual cells isolated from the biological clock can keep daily time all by themselves.