The SCN sends timing signals through multiple downstream pathways, but we still know relatively little about how individual pathways control specific features of daily behavior. Recently, we identified a sparse population of SCN neurons that projects to the dorsomedial hypothalamus (DMH) and regulates the timing and duration of locomotor activity.

We now use this and other pathways as a model for understanding how circadian timing is transmitted and transformed between the SCN and downstream neural circuits. A central question is how signals arriving from the SCN interact with local molecular clocks and other inputs within target neurons to generate appropriately timed behavioral and physiological rhythms.