Suprachiasmatic region of the human hypothalamus: homolog to the primate circadian pacemaker?

The suprachiasmatic nuclei (SCN) of the hypothalamus in mammals, including nonhuman primates, contain a key pacemaker of the circadian timing system. Examination of the histology of the anterior hypothalamus in human fetal, child, and adult brains indicates that there is a cluster of neurons which may be homologous to SCN. These neurons are more diffusely organized and laterally placed in human brains than is the SCN of nonhuman primates.