FUNCTIONAL NEUROANATOMY OF AUDITORY PATHWAYS IN THE SOUND-PRODUCING FISH POLLIMYRUS

We have described the acoustic pathway from the ear to the diencephalo n in a sound-producing fish (Pollimyrus) based on simultaneous neuroph ysiological recordings from single neurons and injections of biotin pa thway tracers at the recording sites. Fundamental transformations of a uditory information from highly phase-locked and entrained responses i n primary eighth nerve afferents and first-order medullary neurons to more weakly phase-locked responses in the auditory midbrain were revea led by physiological recordings. Anatomical pathway tracing uncovered a bilateral array of both first- and second-order medullary nuclei and a perilemniscal nucleus. Interconnections within the medullary audito ry areas were extensive. Medullary nuclei projected to the auditory mi dbrain by means of the lateral lemniscus. Midbrain auditory areas proj ected to both ipsilateral and contralateral optic tecta and to an arra y of three nuclei in the auditory thalamus. The significance of these findings to the elucidation of mechanisms for the analysis of communic ation sounds and spatial hearing in this vertebrate animal is discusse d. J. Comp. Neurol. 401:227-252, 1998. (C) 1998 Wiley-Liss, Inc.