A retinal projection to the paraventricular nuclei of the hypothalamus in the Syrian hamster (Mesocricetus auratus).

The retino-hypothalamic tract of the Syrian hamster (Mesocricetus auratus) was examined using intraocular injections of horseradish peroxidase conjugated to cholera toxin. In addition to the retinal input to the suprachiasmatic nuclei (SCN), a retinal projection to the caudal paraventricular nuclei was identified. This projection may mediate some effects of light upon pineal gland physiology independently of the SCN and the circadian-rhythm generating system.