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Fig. 2 Auditory structures and sites described in text. (a) Topogram of toadfish, revealing saccular
otoliths (sac oto in the otic capsule, enclosed in box). The bi-lobed gas bladder is visible caudal to
the otoliths; scale bar is 3.5 cm. (b) Cartoon of Opsanus tau brain: dorsal view showing general
location of auditory regions. The octaval column consists of the five nuclei receiving input from
VIII, which lie deep to the surface of the medulla, indicated by the grey oval surrounded by the
broken line. The auditory nucleus in the midbrain (nucleus centralis, dashed outline) is beneath the
ventricle in the midbrain (below the optic tectum). Drawing not to scale. (c) Auditory circuit in
toadfish defined by anatomical and physiological studies. Confirmed auditory afferents from the
saccule project to AON and dorsal DON, with some bifurcating fibers that project to both octaval
nuclei. Auditory projections from DON to SOdor and from SOdor to the auditory midbrain (NC)
were obtained anatomically, without physiological confirmation that SOdor has auditory response
characteristics. Dashed line indicates limited evidence for projection from DON to contralateral
SOdor. Abbreviations: AON anterior octaval nucleus, C cerebellum, CC crista cerebellaris, contra
contralateral, dl dorsolateral, dm dorsomedial, DON descending octaval nucleus, NC nucleus centralis, OL olfactory lobe, ON olfactory nerve, OT optic tectum, SOdor dorsal secondary octaval
nucleus, T telencephalon (forebrain), TS torus semicircularis (midbrain), VIIIa anterior branch of
acoustic cranial nerve, VIIIp posterior branch of acoustic cranial nerve (topogram by D. Ketten,
CSI Lab, Woods Hole Oceanographic Institution)
P.L. Edds-Walton
Fig. 2 Auditory structures and sites described in text. (a) Topogram of toadfish, revealing saccular
otoliths (sac oto in the otic capsule, enclosed in box). The bi-lobed gas bladder is visible caudal to
the otoliths; scale bar is 3.5 cm. (b) Cartoon of Opsanus tau brain: dorsal view showing general
location of auditory regions. The octaval column consists of the five nuclei receiving input from
VIII, which lie deep to the surface of the medulla, indicated by the grey oval surrounded by the
broken line. The auditory nucleus in the midbrain (nucleus centralis, dashed outline) is beneath the
ventricle in the midbrain (below the optic tectum). Drawing not to scale. (c) Auditory circuit in
toadfish defined by anatomical and physiological studies. Confirmed auditory afferents from the
saccule project to AON and dorsal DON, with some bifurcating fibers that project to both octaval
nuclei. Auditory projections from DON to SOdor and from SOdor to the auditory midbrain (NC)
were obtained anatomically, without physiological confirmation that SOdor has auditory response
characteristics. Dashed line indicates limited evidence for projection from DON to contralateral
SOdor. Abbreviations: AON anterior octaval nucleus, C cerebellum, CC crista cerebellaris, contra
contralateral, dl dorsolateral, dm dorsomedial, DON descending octaval nucleus, NC nucleus centralis, OL olfactory lobe, ON olfactory nerve, OT optic tectum, SOdor dorsal secondary octaval
nucleus, T telencephalon (forebrain), TS torus semicircularis (midbrain), VIIIa anterior branch of
acoustic cranial nerve, VIIIp posterior branch of acoustic cranial nerve (topogram by D. Ketten,
CSI Lab, Woods Hole Oceanographic Institution)
P.L. Edds-Walton