Retinohypothalamic tract
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The Retinohypothalamic tract (RHT) is a photic input pathway involved in circadian rhythms. The RHT is an input pathway from the retina to the suprachiasmatic nucleus[1] (or nuclei; SCN) in the brain, and is important in the entrainment of the mammalian 'body clock' to the external environment. The retinal cells involved in the RHT are photoreceptive retinal ganglion cells containing the photopigment melanopsin, and they project directly to the SCN. The information these photosensitive ganglion cells receive on day-length is interpreted by the SCN, and passed on to the pineal gland, which then secretes the hormone melatonin in response to this exogenous environmental signal.
[edit] References
- ^ Gooley JJ, Lu J, Chou TC, Scammell TE, Saper CB (2001). "Melanopsin in cells of origin of the retinohypothalamic tract". Nat. Neurosci. 4 (12): 1165. doi:. PMID 11713469.
