Hearing Research xxx (2014) 1e2

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Hearing Research journal homepage: www.elsevier.com/locate/heares

Announcement

Progress in Hearing Research 2014 Barbara Canlon* Karolinska Institutet, Department of Physiology and Pharmacology, von Eulers vag 8, 171 77 Stockholm, Sweden

a r t i c l e i n f o

This article is part of a Special Issue entitled .

Article history: Received 5 February 2014 Accepted 18 February 2014 Available online xxx

Once again there is a fascinating collection of articles in the Annual Reviews 2014. This year’s reviews represent important contributions in selected fields of hearing research. There is an exciting collection of reviews covering the Development of specialized auditory synapses (Wei-Ming and Goodrich, 2014), Progress and Prospects of Prestin (He et al., 2014), Function of transmembrane channel-like proteins for hair cell transduction (Holt et al., 2014), Layering hypothesis for subcortical plasticity (Skoe et al., 2014) and two reviews on Tinnitus (Cacace et al., 2014; Schaette, 2014). The Wei-Ming and Goodrich review, “Morphological and physiological development of auditory synapses” discusses the remarkable specialized characteristics that allow for precise signal transmission in the peripheral and central auditory system during development. The authors describe the structure and function of three crucial synapses of the auditory system: the auditory ribbon synapses, the endbulb of Held and the calyx of Held. The review provides important insights to the morphological and physiological development of these three specialized synapses and the genes that influence their function. The auditory field will definitely appreciate the efforts behind this timely review and their thought provoking statements regarding these developmental feats made by these specialized auditory synapses. This review highlights other articles published in Hearing Research that have focused on the development of these auditory synapses in terms of neuronal activity, morphology and molecular characterization of these highly specialized auditory synapses (Wu and Oertel, 1987; Ryugo et al., 2006; McKay and Oleskevich, 2007; O’Neil et al., 2011; Nakamura and Cramer, 2011; Yang et al., 2011). The He et al., “Prestin at Year 14: Progress and Prospect” sums up recent work on the outer hair cell motor protein prestin which was identified 14 years ago. It is comprehensively written and discusses * Tel.: þ46 8524 87248; fax: þ46 8327 026. E-mail address: [email protected]. http://dx.doi.org/10.1016/j.heares.2014.02.006 0378-5955

the discovery and structure of prestin together with its relation to outer hair cell motility. These authors have made important discoveries in this field regarding the molecular aspects of prestin and therefore have good ground to build this interesting review. While significant progress has undoubtedly been made using a battery of electrophysiological, biochemical, genomics and molecular techniques there are still many uncertainties in understanding the precise mechanisms of how prestin works in the outer hair cells. The review ends with interesting prospects for the future of prestin research. Hearing Research has a long history of articles related to outer hair cell motility and prestin. The classic paper by Davis published in 1983 on an active process in cochlear mechanics was quickly recognized as an important mechanism for cochlear amplification. The discovery of prestin (Zheng et al., 2000) has increased our knowledge of somatic motility. However, there are still active discussions over the contributions of somatic motility and stereocilia mechanics and their role for amplification (Ashmore et al., 2010; Peng and Ricci, 2011). “TMC function in hair cell transduction” by Holt et al. is a timely and an exciting topic. The article begins with a historical overview of the deafness mouse and cloning of the transmembrane channellike gene 1 (TMC1). The authors then discuss several landmarks that focus on the identification of the function of TMC genes in hair cells. This review will be of broad interest to auditory neuroscientists. There is strong evidence that transmembrane channel-like proteins are important for mechanotransduction. Many TMC1 mutations cause deafness in both mice and humans suggesting important roles for the auditory system. Calcium selectivity is selectively affected in the hair cells from TMC1 mutant mice suggesting mechanisms underlying their deafness. Hair cells from Tmc1/Tmc2 doubly deficient mice lack conventional mechanotransduction a finding that clearly demonstrates that expression of either Tmc1 or Tmc2 is required for conventional hair cell transduction. This review also examines the role of Tmc mRNAs and the function of these proteins.

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Announcement / Hearing Research xxx (2014) 1e2

“The layering of auditory experiences in driving experiencedependent subcortical plasticity”. By Skoe et al. (2014) writes an exciting and thoughtful paper which reviews experience dependent plasticity as driven by auditory experiences in the auditory brainstem and midbrain. The review posits a new layering hypothesis that discusses the modulation of the auditory brainstem by experiences over an individual’s lifetime. The authors suggest that the layering hypothesis would result in an auditory fingerprint for the individual that would then be useful for understanding plastic changes in the individual. This information could then be used for optimizing individualized therapy. This is a relatively new approach to understand the total auditory experience of the individual and is suggesting that the field shifts away from analyzing the effects of single experiences and develop new means of examining how different auditory experiences affect the individual. Even though this is a relatively new field for the auditory system, Hearing Research has published a couple of articles in this area (Parbery-Clark et al., 2013; Strait and Kraus, 2014) and this review emphasizes the importance of this new-thinking. Tinnitus continues to be a growing problem and while there is no general treatment for tinnitus, our understanding of the physiological and molecular mechanisms underlying this disability is making progress. The article by Cacace et al., 2014, describes the advantages of using manganese enhanced magnetic resonance imaging (MEMRI) for the detection and quantification of tinnitus. This review points out several important advantages of MEMRI over other imaging techniques. Even though positron emission tomography, functional magnetic resonance imaging and diffusion tensor imaging has been extremely useful in understanding tinnitus (Mirz et al., 1999; Lanting et al., 2009; Benson et al., 2013; Brozoski et al., 2007), the improved resolution with MEMRI allows for the characterization of small distinct regions of the brain from small animal models. This review is an excellent addition to other reviews on tinnitus that have been published in Hearing Research (for ex. Kaltenbach, 2011; Bauer et al., 2013; Husain and Schmidt, 2014). The review by Roland Schaette, “Tinnitus in Men, Mice (as well as other Rodents), and Machines” presents the most recent evidence of the current knowledge regarding the links between peripheral damage and central correlates of tinnitus in animals and humans, and presents current computational models of tinnitus. Important insights into the role of the inner hair cells has been reviewed and continues to support earlier studies on damage to inner hair cells or auditory nerve fibers in tinnitus (Weisz et al., 2006; Schaette and Kempter, 2008). Off-frequency listening further supports a role of inner hair cell damage and both acute tinnitus (Etchelecou et al., 2011), chronic tinnitus (Kiani et al., 2013) or with tonal tinnitus (Moore and Vinay, 2010). The author of this review stresses the importance of treating tinnitus most effectively when off-listening frequencies are taken into account (Schaette et al., 2010). Finally, there is a discussion concerning computational modeling where functional mechanisms underlying tinnitus development are suggested to be a side-effect of the brain’s attempt to compensate for hearing loss.

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Progress in hearing research 2014.

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