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Retinohypothalamic Tract

Meaning

The Retinohypothalamic Tract (RHT) is a dedicated, direct neural pathway connecting specialized intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina to the suprachiasmatic nucleus (SCN) of the hypothalamus, which functions as the body’s master circadian pacemaker. This pathway is exclusively responsible for transmitting non-image-forming light signals that are essential for the process of entrainment, or synchronizing, the internal biological clock to the external environmental light-dark cycle. It is a vital neuroendocrine component regulating sleep, mood, and the cyclical release of hormones.