Connections of the torus semicircularis and oliva superior in the frog, Rana esculenta: A phaseolus vulgaris leucoagglutinin labeling study

Clara Matesz, Á Kulik

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The afferent and efferent connections of the frog principal nucleus (TP) of torus semicircularis (TOS) and superior olive (SO) were examined by employing the anterograde and retrograde transport patterns of Phaseolus vulgaris leucoagglutinin (PHA-L). After injecting the tracer into these nuclei it was found that the TP projected to the ipsilateral posterior and central thalamic nuclei, all subdivisions of the bilateral TOS and the ipsilateral nucleus isthmi (NI). In the rhombencepnalon the projection was restricted mainly to the contralateral SO and the cochlear nucleus (CN). Retrogradely labeled cells were found in most of the areas that contained anterogradely labeled terminals. The termination areas of the SO fibers were similar to the projections of fibers of TP origin in the diencephalic and in the mesencephalic auditory centers. A strong projection was followed into the contralateral SO; the CNs received fibers at both sides. Caudally to the SO the reticular formation, the spinal nucleus of the trigeminal nerve, the solitary nucleus and the dorsal column nuclei were supplied by the fibers of the SO origin. Retrogradely labeled cells ware found in the TOS, tegmental nuclei, solitary nucleus, dorsal column nuclei and in the spinal nucleus of the trigeminal nerve. Our results indicate that the frog auditory pathway is more complex at the level of the secondary and tertiary fiber projections than has been previously recognized.

Original languageEnglish
Pages (from-to)287-301
Number of pages15
JournalActa biologica Hungarica
Issue number1-4
Publication statusPublished - Dec 1 1996



  • Auditory pathway
  • Frog
  • Oliva superior
  • PHA-L labeling
  • Torus semicircularis

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Neurology

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