Absence of tectotectal pathway in the rabbit: an anatomical and electrophysiological study

Absence of tectotectal pathway in rabbits is demonstrated by means of anatomical (retrograde axonal transport of horseradish peroxidase (HRP)) and of physiological (electrical stimulation of the superior colliculus (SC)) methods. Despite the absence of that pathway it was still possible to verify the occurrence of electrophysiological correlates of Sprague's phenomenon. It is suggested that, in rabbits at least, reciprocal inhibitory influences between the colliculi can be mediated by pathway(s) other than the tectotectal projection. It is also hypothesized that the absence of tectotectal pathway could possibly be functionally correlated to a small degree of binocular vision and to a small representation of the ipsilateral visual hemifield in the superior colliculus.