[PDF] Neuronal Input Pathways to the Brain?s Biological Clock and their Functional Significance Jens Hannibal MD, PhD, Dr. Sci, Jan Fahrenkrug (auth.)

Circadian rhythms are entrained daily by environmental photic and non-photic cues. The present review describes the anatomy and functional characteristics of the three major input pathways to the circadian clock mediating entrainment, the retino-hypothalamic tract (RHT), the geniculo-hypothalamic tract (GHT) and the midbrain raphe projection.