Differential organization of crossed and uncrossed projections from the superior olive to the inferior colliculus in the mole

Abstract

Projections from the medial (MSO) and lateral (LSO) superior olivary nuclei to the inferior colliculus (IC) were examined in the mole. In each mole, Fluoro-Gold was injected into one IC and wheat germ-agglutinated horseradish peroxidase (WGA-HRP) into the other IC; most MSO neurons were double-labeled bilaterally, while most LSO neurons were single-labeled bilaterally. The results indicate that the bilateral projections from the MSO and LSO to the IC are mainly established by single MSO neurons with axon collaterals to the IC on both sides, and by two separate populations of LSO neurons with axons to the contralateral or ipsilateral IC.