Synaptic communication of cellular oscillations in the rat suprachiasmatic neurons.

Circadian firing rhythms of cultured rat suprachiasmatic nucleus were measured simultaneously from 4-8 neurons by using a multi-electrode dish and neuronal interactions were examined by a cross-correlation analysis of spontaneous action potentials. Functional connections were detected in the neuron pairs showing synchronized circadian firing rhythms, and when the connections were lost, firing rhythms were desynchronized. After the prolonged treatment with tetrodotoxin, cross-correlation and circadian rhythm synchronization were abolished concomitantly in most neuron pairs. Cellular mechanisms involving Na(+)-channel dependent communication are responsible for the synchronization of the circadian rhythms in individual suprachiasmatic nucleus (SCN) neurons.