Regulation and Integration in the Mammalian Circadian System.
J.M. Kornhausser, D.D.
Ginty, M.E. Greenberg, K.E. Mayo, and J.S. Takahashi. Progress in Brain Research
1996; 111: 191-203
"In mammals the principal pacemaker that generates circadian rhythms is located
in the suprachiasmatic nucleus (SCN) of the hypothalamus, and light information
transmitted from the retina to the SCN entrains this clock."