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BMC Neuroscience

Open Access

Parallel pathways at the auditory periphery

BMC Neuroscience201415(Suppl 1):P193

https://doi.org/10.1186/1471-2202-15-S1-P193

Published: 21 July 2014

We should consider the possibility that Low- and High- spontaneous rate (SR) auditory nerve fibers (ANFs) [1] constitute two different parallel pathways at the auditory periphery. The present study used a computational model of the auditory periphery [2] to demonstrate that Low- and High- SR ANFs have contrasting response properties. Anatomical studies suggest that Low- and High- SR ANF types have separate innervation sites (Figure 1A) on the same inner hair cell; lower-SR fibers synapse on the modiolar side and high-SR fibers synapse on the pillar side [3]. My hypothesis, prior to modeling the tuning curves (Figure 1B), was that Low Spontaneous Rate (Low-SR) fibers have a higher threshold for simulation and thus will have demonstrably sharper frequency selectivity than High-SR fibers. The results of the simulation support this framework; Low-SR ANFs were shown to have sharper frequency tuning (Figure 1B) than High-SR ANFs throughout a range of characteristic frequencies (CFs). While Low-SR ANFs have sharper frequency selectivity (Figure 1B), High-SR ANFs have finer temporal resolution, as the rate of change of the mean firing rate in High-SR ANFs was well above that of Low-SR fibers in the simulation (Figure 1C). It would seem that Low-SR and Medium-SR fibers (i.e. Lower-SR fibers) are optimized for “place theory” frequency coding and High-SR fibers are optimized for “volley-theory” synchronous phase locking. Future modeling efforts might maintain the integrity of these two parallel pathways, optimized for fine spectral (Lower-SR) and fine temporal (High-SR) resolution, by separating rather than summing their respective outputs.
Figure 1

Innervation sites (A), tuning curves (B) and temporal response properties for Low- and High- SR ANFs

Authors’ Affiliations

(1)
Center for Computational Neuroscience and Neural Technology (CompNet), Boston University
(2)
Graduate Program for Neuroscience (GPN), Boston University

References

  1. Liberman MC: Auditory-nerve response from cats raised in a low-noise chamber. J Acoust Soc Am. 1978, 63 (2): 442-455. 10.1121/1.381736.View ArticlePubMedGoogle Scholar
  2. Zilany MSA, Bruce IC, Carney LH: Updated parameters and expanded simulation options for a model of the auditory periphery. J Acoust Soc Am. 2014, 135: 283-286. 10.1121/1.4837815.PubMed CentralView ArticlePubMedGoogle Scholar
  3. Bharadwaj HM, Verhulst S, Shaheen L, Liberman M, Shinn-Cunningham BG: Cochlear neuropathy and the coding of supra-threshold sound. Front Syst Neurosci. 2014, 8 (26): 10.3389/fnsys.2014.00026.Google Scholar

Copyright

© Cantu; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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