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Organization of the auditory brainstem in a lizard, Gekko gecko . I. Auditory nerve, cochlear nuclei, and superior olivary nuclei
Author(s) -
Tang Yezhong,
ChristensenDalsgaard Jakob,
Carr Catherine E.
Publication year - 2012
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23013
Subject(s) - anatomy , brainstem , neuropil , biology , superior olivary complex , sensory system , gecko , auditory system , nucleus , dorsal cochlear nucleus , neuroscience , dorsum , cochlear nucleus , central nervous system , ecology
We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko ( Gekko gecko ). The auditory nerve has two divisions, a rostroventrally directed projection of mid‐ to high best‐frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of low to middle best‐frequency fibers that bifurcate to project to both the NA and the nucleus magnocellularis (NM). The projection to NM formed large somatic terminals and bouton terminals. NM projected bilaterally to the second‐order nucleus laminaris (NL), such that the ipsilateral projection innervated the dorsal NL neuropil, whereas the contralateral projection crossed the midline and innervated the ventral dendrites of NL neurons. Neurons in NL were generally bitufted, with dorsoventrally oriented dendrites. NL projected to the contralateral torus semicircularis and to the contralateral ventral superior olive (SOv). NA projected to ipsilateral dorsal superior olive (SOd), sent a major projection to the contralateral SOv, and projected to torus semicircularis. The SOd projected to the contralateral SOv, which projected back to the ipsilateral NM, NL, and NA. These results suggest homologous patterns of auditory connections in lizards and archosaurs but also different processing of low‐ and high‐frequency information in the brainstem. J. Comp. Neurol. 520:1784–1799, 2012. © 2011 Wiley Periodicals, Inc