title: Auditory pathways to the hypothalamus in ranid frogs.
abstract: Three multisynaptic pathways from the midbrain auditory center (torus semicircularis) of the bullfrog, Rana catesbeiana, to the infundibular hypothalamus were found using the axonal tracer wheat germ agglutinin-horseradish peroxidase. Toral neurons project to the secondary visceral nucleus of the isthmus and to the central and anterior thalamic nuclei of the dorsal thalamus. All 3 of these nuclei project to the infundibular hypothalamus. These findings indicate multiple connections between two centers presumed important for reproductive behavior in frogs, a midbrain sensory region processing acoustic communication signals and a hypothalamic endocrine control area regulating gonadotropin and gonadal steroid secretion.
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000033:anatomy & histology*; D007031:Hypothalamus / Q000033:anatomy & histology*; D008636:Mesencephalon / Q000033:anatomy & histology*; D011892:Rana catesbeiana; D013787:Thalamic Nuclei / Q000033:anatomy & histology