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Published August 8, 1988 | public
Journal Article

Projections of nucleus angularis and nucleus laminaris to the lateral lemniscal nuclear complex of the barn owl

Abstract

Interaural phase and intensity are cues by which the barn owl determines, respectively, the azimuth and elevation of a sound source. Physiological studies indicate that phase and intensity are processed independently in the auditory brainstem of the barn owl. The phases of spectral components of a sound are encoded in nucleus magnocellularis (NM), one of the two cochlear nuclei. NM projects solely and bilaterally to nucleus laminaris (NL), wherein interaural phase difference is computed. The other cochlear nucleus, nucleus angularis (NA), encodes the amplitudes of spectral components of sounds. We report here the projections of NA and NL to the lateral lemniscal nuclei of the barn owl. The lateral lemniscal complex comprises nucleus olivaris superior (SO); nucleus lemnisci lateralis, pars ventralis (LLv); and nucleus ventralis lemnisci lateralis (VLV). At caudal levels, VLV may be divided into a posterior (VLVp) and an anterior (VLVa) subdivision on cytoarchitectonic grounds. At rostral levels, the cytoarchitectural differences diminish and the boundaries between the two subdivisions become obscured. Likewise, our data from anterograde tracing studies suggest that at caudal levels the terminal fields of NA and NL remain confined to VLVp and VLVa, respectively. They merge, however, at rostral levels. The data also suggest that NL projects to the medial portion of the ipsilateral SO and that NA projects bilaterally to all parts of SO and LLv. Studies with the retrograde transport of horseradish peroxidase confirm these projections.

Additional Information

© 1988 Alan R. Liss, Inc. Manuscript Accepted: 1 Mar 1988. We thank Drs. J.J.A. Arends, Catherine Carr, Ichiro Fujita, Andy Moiseff, Ted Sullivan, Susan Volman, and Hermann Wagner for their helpful discussions. Mr. Eugene Akutagawa helped us with the histology. This work was supported by National Science Foundation grant No. BNS8411458 and National Institutes of Health grant No. NS 14617.

Additional details

Created:
August 22, 2023
Modified:
October 25, 2023