Abstract
The circadian clock in the suprachiasmatic nucleus (SCN) is composed of thousands of oscillator neurons, each dependent on the cell-autonomous action of a defined set of circadian clock genes. One of the major questions remain how these individual oscillators are organized into a biological clock producing a coherent output orchestrating all the different daily changes in physiology and behavior.It has been suggested that the action potentials in the SCN are not a part of the internal timekeeping mechanism of the circadian pacemaker; rather, the electrical impulses function to couple the pacemaker to its input and output pathway. We have established SCN neuronal recording from freely moving mice. With the availability of genetic techniques, mouse is the most useful model to study the molecular and cellular basis of circadian behaviors. Here we report the continuous and long-term recording of neural activity in SCN and subparaventricular zone (SPZ), the relay nuclei of SCN output. Clock mutant mice, originally identified in an N-ethyl-N-nitrosourea mutagenesis screen, showed intriguing circadian phenotype not only in behavior but circadian coupling among those nuclei. This in vivo recording technique, once coupled with mouse genetics, should be valuable to the study of complex relationship between the genes, neural output, and circadian behaviors. [J Physiol Sci. 2007;57 Suppl:S63]
