Projections from auditory structures to the superior colliculus in the rat.

Auditory inputs to the middle and deep layers of the central area of the superior colliculus were studied in rats with horseradish peroxidase (HRP) injections into the superior colliculus. The most powerful projections were found from the dorsal nucleus of the lateral lemniscus bilaterally, with prevailing ipsilateral projections. A smaller number of labelled cells was observed in the ipsilateral external nucleus of the inferior colliculus and a few labelled cells were distributed in the dorsomedial part of the inferior colliculus ipsilaterally. Descending connections from the auditory cortex originated from the dorsal part of the ipsilateral auditory cortical area, in layer Vb.