Superior colliculus efferents to the hypothalamus.

The projection of the superior colliculus to the hypothalamus was studied in the rabbit and rat with light and electron microscopic techniques. This projection system, as demonstrated with the anterograde transport of tritiated leucine, proline, adenosine or horseradish peroxidase, is primarily to dendrites located in the ipsilateral optic and supraoptic tracts. The dendrites originate from cells located in the lateral and anterior hypothalamic areas, retrochiasmatic area and supraoptic nucleus. Thus, the ventral tier of the hypothalamus appears to receive both separate and overlapping visual and multimodal sensory-motor inputs from the retina, ventral lateral geniculate nucleus and superior colliculus.