Relevance of network organization in scn clock function

Abstract

The bilateral suprachiasmatic nuclei (SCN) of the hypothalamus are the loci of a circadian pacemaker that coordinates rhythms throughout the body. The ~10,000 cells of each nucleus are organized into distinct core and shell divisions, each of which is comprised of clusters of various cell types. In dispersed cell preparation`s, individual SCN neurons express a wide range of circadian periods. In a slice preparation, there is a characteristic peak and trough time of clock gene expression in specific subregions, indicating that the networks into which cells are organized are an important aspect of SCN function. Understanding the relationship of individual cells to that of larger neuronal groupings and to brain circuits in which they participate is a problem of general interest in neuroscience. The SCN is an especially tractable system for such queries as the function of this nucleus is known, and circadian rhythms in activity of individual cells and in the SCN as a whole can each be tracked and associated with the overall behavior and physiology of the intact animal.