Network properties of the circadian clock: an integration of computational methods and empirical data

Abstract

Evolutionary most species have developed internal clocks, enabling them to optimally coordinate their physiology and behavior with the local environment. In mammals, the suprachiasmatic nucleus (SCN) serves as the master clock of the body and is located in the hypothalamus in the brain. Circadian rhythms in electrical activity function as output of the SCN and are generated by the complex interplay between SCN neurons. The research in this thesis aimed at identifying network properties of the circadian clock by investigating the four functional components of the SCN: (1) light input to the SCN, (2) neural network synchronization within the SCN, (3) output from the SCN to brain and body, and (4) feedback from these processes back to the SCN. We used empirical data together with computational methods to obtain new insights in the network properties of the circadian clock. We furthermore identified similarities and differences in the SCN network between nocturnal and diurnal species. As there are many diseases affecting clock function, understanding the SCN network is a first step towards maintaining health.