Anatomical and electrophysiological demonstration of tectotectal pathway in the golden hamster

Both the retrograde transport of horseradish peroxidase (HRP) and extracellular single unit recording have been employed to demonstrate the existence of an intertectal pathway in the golden hamster. The cells of origin of this projection are located primarily in the stratum griseum intermediate and stratum griseum profundum of the anterior one-half of the colliculus and respond, in most cases, only to somatosensory stimuli. These findings cast doubt on the recently proposed generalization [13] that this pathway may be rudimentary or even absent in animals with limited collicular binocularity or a small ipsilateral hemifield representation in the colliculus.