Circadian Rhythms are endogenous self-sustaining oscillations that organize the timing of biological systems to optimize physiology and behavior, and health. Circadian Rhythms:
- Are synchronized by recurring environmental cues;
- Anticipate the external environment;
- Allow effective response to challenges and opportunities in the physical and social environment;
- Modulate homeostasis within the brain and other (central/peripheral) systems, tissues and organs;
- Are evident across levels of organization including molecules, cells, circuits, systems, organisms, and social systems.
SCN Synchronizing and Modulating AgentsAVPCalbindincAMPcGMPNOSteroid hormonesVIP
InputRaphe to SCN projectionRetinal cellsRetino-hypothalamic tractRetinogeniculate tract
OutputBasolateral amygdala/ HippocampusCentral extended amygdala (central nucleus of the amygdala / Bed nucleus of the stria terminalis)HPA axisHypothalamic neuroendocrine cell groupsHypothalamic orexin projectionsPVN, DMH, subparaventricular zone, PVTSCN/PVN/SCG/pinealSympathetic / parasympathetic nervous system
Intrinsic to SCNSuprachiasmatic nucleus (SCN) core/shell
Genetic Approaches – genome-wide association study, candidate gene, epigenomics, circadian genomics (temporal gene expression), mutagenesis, gene targeting, quantitative trait loci.