Spatial organization of the reciprocal connections between the cat dorsal and anteroventral cochlear nuclei

We are studying the interconnections between the anteroventral cochlear nuc leus (AVCN) and the dorsal cochlear nucleus (DCN). Biotinylated dextran was injected into the DCN, where the best frequency of responses was also reco rded. Ventrotubercular neurons in AVCN were labeled, along with cochlear ne rve fibers and the axons of cells in DCN. In AVCN, a central band of labele d cochlear nerve axons and large endbulbs was labeled. Bordering this band was a 'fringe' of smaller tuberculoventral axonal endings forming pericellu lar nests. Most AVCN neurons projecting to DCN were stellate, elongate, or giant cells, located in the posterior division of AVCN, regardless of the D CN injection site. About 75% of the labeled AVCN cells lay within the bands of labeled cochlear nerve fibers. Another 15% were in the outer fringes on either side of these bands, while 10% were outside the bands and the fring es. These findings suggest that most AVCN neurons projecting to the DCN con form to the tonotopic map. A significant portion of the ventrotubercular ne urons occupy side-bands in AVCN. Reciprocally, the tuberculoventral tract f orms a robust fringe of axonal endings flanking the central bands. The neur onal and axonal bands and side-bands may underlie excitatory and inhibitory signal transformations. (C) 1999 Published by Elsevier Science B.V. All ri ghts reserved.