The inner ear of fishes contains three paired otolithic endorgans, the saccule, lagena, and utricle, which function as biological accelerometers. The saccule is the largest otolithin most fishes and much of our current understanding on auditory function in this diverse group of vertebrates is derived from anatomical and neurophysiological studies on this endorgan. In contrast, less is known about how the utricle contributes to auditory functions. Chronically implanted electrodes were used, along with neural telemetry or tethers to record primary afferent responses from the utricular nerve in free-ranging and naturally behaving oyster toadfish Opsanus tau Linnaeus. The hypothesis was that the utricle plays a role in detecting underwater sounds, including conspecific vocalizations, and exhibits directional sensitivity. Utricular afferents responded best to low frequency (80-200 Hz) pure tones and to playbacks of conspecific boatwhistles and grunts (80 to 180 Hz fundamental frequency), with the majority of the units (∼75%) displaying a clear, directional response, which may allow the utricle to contribute to sound detection and localization during social interactions. Responses were well within the sound intensity levels of toadfish vocalization (approximately 140 SPL dBrms re: 1µPa with fibers sensitive to thresholds of approximately 120 SPL dBrms re: 1µPa). Neurons were also stimulated by self-generated body movements such as opercular movements and swimming. This study is the first to investigate underwater sound-evoked response properties of primary afferents from the utricle of an unrestrained/unanesthetized free-swimming teleost fish. These data provide experimental evidence that the utricle has an auditory function, and can contribute to directional hearing to facilitate sound localization.
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RESEARCH ARTICLE|
01 January 2015
Directional sound sensitivity in utricular afferents in the toadfish, Opsanus tau
Karen P. Maruska,
Karen P. Maruska
1
Marine Biological Laboratory Woods Hole
, MA 02543
, USA
2
Biology Department University of Minnesota Duluth
, Duluth, MN 55812
, USA
3
Department of Biological Sciences
, Louisiana State University
, Baton Rouge, LA 70803
, USA
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Allen F. Mensinger
Allen F. Mensinger
*
1
Marine Biological Laboratory Woods Hole
, MA 02543
, USA
2
Biology Department University of Minnesota Duluth
, Duluth, MN 55812
, USA
*Author for Correspondence: amensing@d.umn.edu
Search for other works by this author on:
Karen P. Maruska
1
Marine Biological Laboratory Woods Hole
, MA 02543
, USA
2
Biology Department University of Minnesota Duluth
, Duluth, MN 55812
, USA
3
Department of Biological Sciences
, Louisiana State University
, Baton Rouge, LA 70803
, USA
Allen F. Mensinger
*
1
Marine Biological Laboratory Woods Hole
, MA 02543
, USA
2
Biology Department University of Minnesota Duluth
, Duluth, MN 55812
, USA
*Author for Correspondence: amensing@d.umn.edu
Received:
13 Oct 2014
Accepted:
10 Apr 2015
Online ISSN: 1477-9145
Print ISSN: 0022-0949
© 2015. Published by The Company of Biologists Ltd
2015
J Exp Biol jeb.115345.
Article history
Received:
13 Oct 2014
Accepted:
10 Apr 2015
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Karen P. Maruska, Allen F. Mensinger; Directional sound sensitivity in utricular afferents in the toadfish, Opsanus tau. J Exp Biol 2015; jeb.115345. doi: https://doi.org/10.1242/jeb.115345
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