197
© Springer International Publishing Switzerland 2016
J.A. Sisneros (ed.), Fish Hearing and Bioacoustics, Advances in Experimental
Medicine and Biology 877, DOI 10.1007/978-3-319-21059-9_10
What the Toadfish Ear Tells the Toadfish
Brain About Sound
Peggy L. Edds-Walton
Abstract Of the three, paired otolithic endorgans in the ear of teleost fishes, the
saccule is the one most often demonstrated to have a major role in encoding frequencies of biologically relevant sounds. The toadfish saccule also encodes sound
level and sound source direction in the phase-locked activity conveyed via auditory
afferents to nuclei of the ipsilateral octaval column in the medulla. Although paired
auditory receptors are present in teleost fishes, binaural processes were believed to
be unimportant due to the speed of sound in water and the acoustic transparency of
the tissues in water. In contrast, there are behavioral and anatomical data that support binaural processing in fishes. Studies in the toadfish combined anatomical
tract-tracing and physiological recordings from identified sites along the ascending
auditory pathway to document response characteristics at each level. Binaural computations in the medulla and midbrain sharpen the directional information provided
by the saccule. Furthermore, physiological studies in the central nervous system
indicated that encoding frequency, sound level, temporal pattern, and sound source
direction are important components of what the toadfish ear tells the toadfish brain
about sound.
Keywords Descending octaval nucleus • Hearing • Saccule • Torus semicircularis
P.L. Edds-Walton (*)
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Science Education and Enrichment, 6864 Rycroft Drive, Riverside, CA 9250, USA
e-mail: seewalton@gmail.com
© Springer International Publishing Switzerland 2016
J.A. Sisneros (ed.), Fish Hearing and Bioacoustics, Advances in Experimental
Medicine and Biology 877, DOI 10.1007/978-3-319-21059-9_10
What the Toadfish Ear Tells the Toadfish
Brain About Sound
Peggy L. Edds-Walton
Abstract Of the three, paired otolithic endorgans in the ear of teleost fishes, the
saccule is the one most often demonstrated to have a major role in encoding frequencies of biologically relevant sounds. The toadfish saccule also encodes sound
level and sound source direction in the phase-locked activity conveyed via auditory
afferents to nuclei of the ipsilateral octaval column in the medulla. Although paired
auditory receptors are present in teleost fishes, binaural processes were believed to
be unimportant due to the speed of sound in water and the acoustic transparency of
the tissues in water. In contrast, there are behavioral and anatomical data that support binaural processing in fishes. Studies in the toadfish combined anatomical
tract-tracing and physiological recordings from identified sites along the ascending
auditory pathway to document response characteristics at each level. Binaural computations in the medulla and midbrain sharpen the directional information provided
by the saccule. Furthermore, physiological studies in the central nervous system
indicated that encoding frequency, sound level, temporal pattern, and sound source
direction are important components of what the toadfish ear tells the toadfish brain
about sound.
Keywords Descending octaval nucleus • Hearing • Saccule • Torus semicircularis
P.L. Edds-Walton (*)
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Science Education and Enrichment, 6864 Rycroft Drive, Riverside, CA 9250, USA
e-mail: seewalton@gmail.com