Real-time imaging reveals spatiotemporal dynamics of cellular circadian clocks

Circadian clocks have been localized to discrete sites within the nervous systems of several organisms, and in mammals to the suprachiasmatic nucleus (SCN) in the anterior hypothalamus. The clock in the SCN is composed of multiple autonomous single-cell oscillators, and new studies now allow an unprecedented look at their oscillatory activities over repeated cycles in tissue slices in vitro. Initial data reinforce the importance of intercellular membrane events for constructing a functional and reliable tissue pacemaker.