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82nd Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

01.06. - 05.06.2011, Freiburg

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Influence of hearing experience on tonotopy and interneuronal communication in the auditory brainstem of rats: A c-Fos study

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German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. 82nd Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery. Freiburg, 01.-05.06.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. Doc11hno42

doi: 10.3205/11hno42, urn:nbn:de:0183-11hno427

Published: August 3, 2011

© 2011 Rosskothen-Kuhl et al.
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Introduction: The immediate-early-gene c-fos is one of the first genes to be expressed in the auditory system following sensory or electrical intracochlear stimulation (EIS). As a component of the activator-protein-1 signaling pathway it triggers various genes, among them several involved in neuroplastic remodelling.

Methods: The analysis of the c-Fos expression pattern due to unilateral cochlear implant stimulation lasting 45 min to 5 h was done by use of immunohistochemistry and in-situ-hybridization for the anteroventral cochlear nucleus (AVCN) and the central inferior colliculus (CIC) from normally hearing and neonatally deafened adult rats. The effectiveness of the stimulation was examined by measurement of the electrical auditory brainstem response.

Results: Due to EIS of normally hearing animals a tonotopic c-Fos expression in the ipsilateral AVCN and contralateral CIC can be observed according to the stimulation position. In deafened rats, neurons expressing c-Fos beyond this tonotopic borders with a significantly increased number of c-Fos positive nuclei for each point of time compared to hearing rats. Depending on stimulation duration, the c-Fos pattern also significantly differs depending on hearing experience. In the ipsilateral AVCN of deafened rats the number of c-Fos positive nuclei rises linearly, whereas in hearing rats a non-linear c-Fos expression could be detected. For the CIC a non-linear c-Fos expression was observed for both experimental groups, distinguishable by a local maximum at 73 min for the deafened and at 2 h for the hearing rats.

Conclusion: Absence of hearing experience causes 2 fundamental differences on neurons and their interaction under sustained sensory stimulation: 1. AVCN and CIC largely disregard tonotopic organization. 2. Deafened rats showed a modified interneuronal networking in the auditory system distinguishable by e.g. a linear increase of the population of c-Fos positive nuclei in the AVCN compared to a non-linear growth in hearing rats.

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References

1.
Rosskothen N, Hirschmüller-Ohmes I, Illing RB. AP-1 activity rises by stimulation-dependent c-Fos expression in auditory neurons. Neuroreport. 2008;19(11):1091-3.
2.
Rosskothen-Kuhl N, Illing, RB. Nonlinear development of the populations of neurons expressing c-Fos under sustained electrical intracochlear stimulation in the rat auditory brainstem. Brain Research. 2010;1347:33-41.