Effect of monopolar and bipolar electric stimulation on survival and size of human spiral ganglion cells as studied by postmortem histopathology.
This study is designed to test the hypothesis that chronic electrical stimulation tends to preserve SGCs in implanted hearing-impaired ears. A total of 26 pairs of temporal bones were studied from 26 individuals who in life suffered bilateral profound hearing impairment that was symmetric (in degree of impairment and etiology) across ears and then underwent unilateral cochlear implantation. The subjects were divided in two groups by stimulus configuration: bipolar (n = 16) or monopolar (n = 10). The temporal bones were prepared for histological review by standard methods and two measures of SGC status w...
Source: Hearing Research - May 6, 2013 Category: Audiology Authors: Seyyedi M, Eddington DK, Nadol JB Tags: Hear Res Source Type: research

RNA analysis of inner ear cells from formalin fixed paraffin embedded (FFPE) archival human temporal bone section using laser microdissection - A technical report.
CONCLUSION: We detected COCH and SLC26A5 mRNA in specific structures and cells of the inner ear from archival human temporal bone. Our innovative method using laser microdissection and semi-nested RT-PCR should advance future RNA study of human inner ear diseases. PMID: 23660400 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - May 6, 2013 Category: Audiology Authors: Kimura Y, Kubo S, Koda H, Shigemoto K, Sawabe M, Kitamura K Tags: Hear Res Source Type: research

Effects of hearing aid amplification on voice F0 variability in speakers with prelingual hearing loss.
Abstract To investigate the audio-vocal feedback responses of (F0) to hearing amplification in severe-to-profound prelingual hearing loss (SPHL) using power spectral analysis of F0 contour of sustained vowels. Sustained phonations of vowel/a/of seventeen participants with SPHL were acquired with and without hearing-aid amplifications. The vocal intensity was visually fed back to the participants to help controlling the vocal intensity at 65-75 dBA and 85-95 dBA. The F0 contour of the phonations was extracted and submitted to spectral analysis to measure the extent of F0 fluctuations at different frequenc...
Source: Hearing Research - May 4, 2013 Category: Audiology Authors: Lee GS, Liu C, Lee SH Tags: Hear Res Source Type: research

Improving speech perception in noise with current focusing in cochlear implant users.
In this study, we compared speech perception in noise with experimental monopolar and partial tripolar speech processing strategies. The two strategies were matched in terms of number of active electrodes, microphone, filterbanks, stimulation rate and loudness (although both strategies used a lower stimulation rate than typical clinical strategies). The results of this study showed a significant improvement in speech perception in noise with partial tripolar stimulation. All subjects benefited from the current focused speech processing strategy. There was a mean improvement in speech recognition threshold of 2.7 dB in...
Source: Hearing Research - May 1, 2013 Category: Audiology Authors: Srinivasan AG, Padilla M, Shannon RV, Landsberger DM Tags: Hear Res Source Type: research

Cisplatin-induced ototoxicity: Transporters playing a role in cisplatin toxicity.
Abstract Cisplatin is a potent antineoplastic agent widely used for a variety of cancer types. Unfortunately, its use leads to dose limiting side effects such as ototoxicity. Up to 93% of patients receiving cisplatin chemotherapy will develop progressive and irreversible sensorineural hearing loss which leads to a decreased quality of life in cancer survivors. No treatment is currently available for cisplatin-induced ototoxicity. It appears that cisplatin causes apoptosis by binding DNA, activating the inflammatory cascade as well as generating oxidative stress in the cell. Various studies have aimed to assess the...
Source: Hearing Research - May 1, 2013 Category: Audiology Authors: Waissbluth S, Daniel SJ Tags: Hear Res Source Type: research

Effects of sex and age on auditory spatial scene analysis.
Abstract Recently, it has been demonstrated that men outperform women in spatial analysis of complex auditory scenes (Zündorf et al., 2011). The present study investigated the relation between the effects of ageing and sex on the spatial segregation of concurrent sounds in younger and middle-aged adults. The experimental design allowed simultaneous presentation of target and distractor sound sources at different locations. The resulting spatial "pulling" effect (that is, the bias of target localization toward that of the distractor) was used as a measure of performance. The pulling effect was s...
Source: Hearing Research - May 1, 2013 Category: Audiology Authors: Lewald J, Hausmann M Tags: Hear Res Source Type: research

Characterization of a novel ENU-generated myosin VI mutant mouse strain with congenital deafness and vestibular dysfunction.
Abstract Myosin VI (Myo6) is known to play an important role in the mammalian auditory and vestibular systems. We have identified a novel N-ethyl-N-nitrosourea mutagenised mouse strain, charlie, carrying an intronic Myo6 splice site mutation. This mutation (IVS5+5G > A) results in skipping of exon 5, and is predicted to cause a frameshift and premature termination of the protein. We detected essentially no Myo6 transcript in tissue from charlie homozygous mutant mice (Myo6(chl/chl)). Myo6(chl/chl) mice exhibit vestibular dysfunction and profound hearing impairment when first tested at four weeks of ag...
Source: Hearing Research - May 1, 2013 Category: Audiology Authors: Williams LH, Miller KA, Dahl HH, Manji SS Tags: Hear Res Source Type: research

Auditory evoked magnetic fields in individuals with tinnitus.
Abstract Some forms of tinnitus are likely to be perceptual consequences of altered neural activity in the central auditory system triggered by damage to the auditory periphery. Animal studies report changes in the evoked responses after noise exposure or ototoxic drugs in inferior colliculus and auditory cortex. However, human electrophysiological evidence is rather equivocal: increased, reduced or no difference in N1/N1m evoked amplitudes and latencies in tinnitus participants have been reported. The present study used magnetoencephalography to seek evidence for altered evoked responses in people with tinnitus c...
Source: Hearing Research - April 29, 2013 Category: Audiology Authors: Sereda M, Adjamian P, Edmondson-Jones M, Palmer AR, Hall DA Tags: Hear Res Source Type: research

Electrically evoked compound action potential artifact rejection by independent component analysis: Technique validation.
Abstract The electrically-evoked compound action potential (ECAP) is the synchronous whole auditory nerve activity in response to an electrical stimulus, and can be recorded in situ on cochlear implant (CI) electrodes. A novel procedure (ECAP-ICA) to isolate the ECAP from the stimulation artifact, based on independent component analysis (ICA), is described here. ECAPs with artifact (raw-ECAPs) were sequentially recorded for the same stimulus on 9 different intracochlear recording electrodes. The raw-ECAPs were fed to ICA, which separated them into independent sources. Restricting the ICA projection to 4 independen...
Source: Hearing Research - April 28, 2013 Category: Audiology Authors: Akhoun I, McKay CM, El-Deredy W Tags: Hear Res Source Type: research

Amplitude-modulation detection by gerbils in reverberant sound fields.
Abstract Reverberation can dramatically reduce the depth of amplitude modulations which are critical for speech intelligibility. Psychophysical experiments indicate that humans' sensitivity to amplitude modulation in reverberation is better than predicted from the acoustic modulation depth at the receiver position. Electrophysiological studies on reverberation in rabbits highlight the contribution of neurons sensitive to interaural correlation. Here, we use a prepulse-inhibition paradigm to quantify the gerbils' amplitude modulation threshold in both anechoic and reverberant virtual environments. Data show that pr...
Source: Hearing Research - April 18, 2013 Category: Audiology Authors: Lingner A, Kugler K, Grothe B, Wiegrebe L Tags: Hear Res Source Type: research

How do auditory cortex neurons represent communication sounds?
ne JM Abstract A major goal in auditory neuroscience is to characterize how communication sounds are represented at the cortical level. The present review aims at investigating the role of auditory cortex in the processing of speech, bird songs and other vocalizations, which all are spectrally and temporally highly structured sounds. Whereas earlier studies have simply looked for neurons exhibiting higher firing rates to particular conspecific vocalizations over their modified, artificially synthesized versions, more recent studies determined the coding capacity of temporal spike patterns, which are prominent in p...
Source: Hearing Research - April 17, 2013 Category: Audiology Authors: Gaucher Q, Huetz C, Gourévitch B, Laudanski J, Occelli F, Edeline JM Tags: Hear Res Source Type: research

MEMRO 2012 - Middle-ear bridge between science and otology.
PMID: 23598165 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - April 15, 2013 Category: Audiology Authors: Cho JH, Puria S, Gummer AW Tags: Hear Res Source Type: research

Investigation of bacterial biofilm in the human middle ear using optical coherence tomography and acoustic measurements.
This article is part of a Special Issue entitled "MEMRO 2012". PMID: 23588039 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - April 12, 2013 Category: Audiology Authors: Nguyen CT, Robinson SR, Jung W, Novak MA, Boppart SA, Allen JB Tags: Hear Res Source Type: research

Insensitivity of the audiogram to carboplatin induced inner hair cell loss in chinchillas.
Abstract Noise trauma, aging, and ototoxicity preferentially damage the outer hair cells of the inner ear, leading to increased hearing thresholds and poorer frequency resolution. Whereas outer hair cells make synaptic connections with less than 10% of afferent auditory nerve fibers (type-II), inner hair cells make connections with over 90% of afferents (type-I). Despite these extensive connections, little is known about how selective inner hair cell loss impacts hearing. In chinchillas, moderate to high doses of the anticancer compound carboplatin produce selective inner hair cell and type-I afferent loss with li...
Source: Hearing Research - April 6, 2013 Category: Audiology Authors: Lobarinas E, Salvi R, Ding D Tags: Hear Res Source Type: research

Musicians change their tune: How hearing loss alters the neural code.
Abstract Individuals with sensorineural hearing loss have difficulty understanding speech, especially in background noise. This deficit remains even when audibility is restored through amplification, suggesting that mechanisms beyond a reduction in peripheral sensitivity contribute to the perceptual difficulties associated with hearing loss. Given that normal-hearing musicians have enhanced auditory perceptual skills, including speech-in-noise perception, coupled with heightened subcortical responses to speech, we aimed to determine whether similar advantages could be observed in middle-aged adults with hearing lo...
Source: Hearing Research - April 6, 2013 Category: Audiology Authors: Parbery-Clark A, Anderson S, Kraus N Tags: Hear Res Source Type: research

Superior-semicircular-canal dehiscence: Effects of location, shape, and size on sound conduction.
In this study, BC excitations were simulated by applying rigid-body vibrations to the model along the directions of the (arbitrarily defined) x, y, and z axes of the model. Simulation results are consistent with previous clinical measurements on patients with an SSCD and with results from earlier lumped-element electrical-circuit modeling studies, with the dehiscence decreasing the hearing threshold (i.e., increasing vBM) by about 35 dB for BC excitation at low frequencies, while for AC excitation the dehiscence increases the hearing threshold (i.e., decreases vBM) by about 15 dB. A new finding from this study is...
Source: Hearing Research - April 3, 2013 Category: Audiology Authors: Kim N, Steele CR, Puria S Tags: Hear Res Source Type: research

Loudness functions with air and bone conduction stimulation in normal-hearing subjects using a categorical loudness scaling procedure.
This article is part of a Special Issue entitled "MEMRO 2012". PMID: 23562775 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - April 3, 2013 Category: Audiology Authors: Stenfelt S, Zeitooni M Tags: Hear Res Source Type: research

The dominant role of inhibition in creating response selectivities for communication calls in the brainstem auditory system.
Abstract This review is concerned with how communication calls are processed and represented by populations of neurons in both the inferior colliculus (IC), the auditory midbrain nucleus, and the dorsal nucleus of the lateral lemniscus (DNLL), the nucleus just caudal to the IC. The review has five sections where focus in each section is on inhibition and its role in shaping response selectivity for communication calls. In the first section, the lack of response selectivity for calls in DNLL neurons is presented and discusses why inhibition plays virtually no role in shaping selectivity. In the second section, the ...
Source: Hearing Research - March 29, 2013 Category: Audiology Authors: Pollak GD Tags: Hear Res Source Type: research

Characterizing the ear canal acoustic impedance and reflectance by pole-zero fitting.
This study characterizes middle ear complex acoustic reflectance (CAR) and impedance by fitting poles and zeros to real-ear measurements. The goal of this work is to establish a quantitative connection between pole-zero locations and the underlying physical properties of CAR data. Most previous studies have analyzed CAR magnitude; while the magnitude accounts for reflected power, it does not encode latency information. Thus, an analysis that studies the real and imaginary parts of the data together, being more general, should be more powerful. Pole-zero fitting of CAR data is examined using data compiled from various studi...
Source: Hearing Research - March 22, 2013 Category: Audiology Authors: Robinson SR, Nguyen CT, Allen JB Tags: Hear Res Source Type: research

Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning.
In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40-60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40-440 &m...
Source: Hearing Research - March 19, 2013 Category: Audiology Authors: Cros O, Borga M, Pauwels E, Dirckx JJ, Gaihede M Tags: Hear Res Source Type: research

The Bonebridge: Preclinical evaluation of a new transcutaneously-activated bone anchored hearing device.
CONCLUSIONS: Preclinical results imply that the BB has functional performance similar to the BAHA and could be beneficial to patients suffering with conductive and mixed hearing losses as well as for those with unilateral impairment. Based on these preliminary results, a carefully designed clinical trial with conservative inclusion criteria can be recommended. This article is part of a Special Issue entitled "MEMRO 2012". PMID: 23467173 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - March 1, 2013 Category: Audiology Authors: Huber AM, Sim JH, Xie YZ, Chatzimichalis M, Ullrich O, Röösli C Tags: Hear Res Source Type: research

Two-port network analysis and modeling of a balanced armature receiver.
This study analyzes a widely-used commercial hearing-aid receiver ED series, manufactured by Knowles Electronics, Inc. Electromagnetic transducer modeling must consider two key elements: a semi-inductor and a gyrator. The semi-inductor accounts for electromagnetic eddy-currents, the 'skin effect' of a conductor (Vanderkooy, 1989), while the gyrator (McMillan, 1946; Tellegen, 1948) accounts for the anti-reciprocity characteristic [Lenz's law (Hunt, 1954, p. 113)]. Aside from Hunt (1954), no publications we know of have included the gyrator element in their electromagnetic transducer models. The most prevalent method of tran...
Source: Hearing Research - February 26, 2013 Category: Audiology Authors: Kim N, Allen JB Tags: Hear Res Source Type: research

Estimation of bone conduction skull transmission by hearing thresholds and ear-canal sound pressure.
on B Abstract Bone conduction sound transmission in the human skull and the occlusion effect were estimated from hearing thresholds and ear-canal sound pressure (ECSP) measured by a probe tube microphone when stimulation was at three positions on the skull (ipsilateral mastoid, contralateral mastoid, and forehead). The measurements were done with the ear-canal open as well as occluded by an ear-plug. Depending on the estimation method, transcranial transmission at frequencies below 1 kHz was between -8 and 5 dB, around 0 dB at 1 kHz that decreased with frequency to between -17 and -7 dB at 8 kHz. The forehead tran...
Source: Hearing Research - February 16, 2013 Category: Audiology Authors: Reinfeldt S, Stenfelt S, Håkansson B Tags: Hear Res Source Type: research

Current concepts in age-related hearing loss: epidemiology and mechanistic pathways.
Abstract Age-related hearing loss (AHL), also known as presbycusis, is a universal feature of mammalian aging and is characterized by a decline of auditory function, such as increased hearing thresholds and poor frequency resolution. The primary pathology of AHL includes the hair cells, stria vascularis, and afferent spiral ganglion neurons as well as the central auditory pathways. A growing body of evidence in animal studies has suggested that cumulative effect of oxidative stress could induce damage to macromolecules such as mitochondrial DNA (mtDNA) and that the resulting accumulation of mtDNA mutations/deletio...
Source: Hearing Research - February 16, 2013 Category: Audiology Authors: Yamasoba T, Lin FR, Someya S, Kashio A, Sakamoto T, Kondo K Tags: Hear Res Source Type: research

Neural substrates predicting improvement of tinnitus after cochlear implantation in patients with single-sided deafness.
Abstract Notwithstanding successful reduction of tinnitus after cochlear implantation (CI) in patients with single-sided deafness (SSD) in recent studies, neither the exact mechanism of suppression nor the predictors of the amount of improvement are fully understood yet. We collected quantitative electroencephalography (qEEG) data from nine SSD patients who underwent CI for tinnitus management. By correlating the degree of improvement in tinnitus intensity and tinnitus-related distress with preoperative source-localized qEEG findings and comparing qEEG findings of patients with marked improvement after CI with tho...
Source: Hearing Research - February 13, 2013 Category: Audiology Authors: Song JJ, Punte AK, De Ridder D, Vanneste S, Van de Heyning P Tags: Hear Res Source Type: research

Stem Cell Transplantation via the Cochlear Lateral Wall for Replacement of Degenerated Spiral Ganglion Neurons.
In this study, we attempted to establish a new stem cell transplantation route into the cochlea via the cochlear lateral wall (CLW). First, we tested the precision of this route by injecting Fluorogold into the CLW and next assessed its safety by mock surgeries. Then, using a degenerated SGN animal model, we transplanted neural stem cells (NSCs), derived from the olfactory bulb of C57BL/6- green fluorescent protein (GFP) mice, via the CLW route and examined the cells' distribution in the cochlea. We found the CLW transplantation route is precise and safe. In addition, NSCs migrated into RC with a high efficiency and differ...
Source: Hearing Research - February 9, 2013 Category: Audiology Authors: Zhang PZ, He Y, Jiang XW, Chen FQ, Chen Y, Shi L, Chen J, Chen X, Li X, Xue T, Wang Y, Mi WJ, Qiu JH Tags: Hear Res Source Type: research

Expression and Dexamethasone-induced Nuclear Translocation of Glucocorticoid and Mineralocorticoid Receptors in Guinea Pig Cochlear Cells.
Abstract Glucocorticoids (GC) are powerful anti-inflammatory agents frequently used to protect the auditory organ against damage associated with a variety of conditions, including noise exposure and ototoxic drugs as well as bacterial and viral infections. In addition to glucocorticoid receptors (GC-R), natural and synthetic GC are known to bind mineralocorticoid receptors (MC-R) with great affinity. We used light and laser scanning confocal microscopy to investigate the expression of GC-R and MC-R in different cell populations of the guinea pig cochlea, and their translocation to different cell compartments after...
Source: Hearing Research - February 8, 2013 Category: Audiology Authors: Kil SH, Kalinec F Tags: Hear Res Source Type: research

Understanding the effect of noise on electrical stimulation sequences in cochlear implants and its impact on speech intelligibility.
Abstract The present study investigates the most important factors that limit the intelligibility of the cochlear implant (CI) processed speech in noisy environments. The electrical stimulation sequences provided in CIs are affected by the noise in the following three manners. First of all, the natural gaps in the speech are filled, which distorts the low-frequency ON/OFF modulations of the speech signal. Secondly, speech envelopes are distorted to include modulations of both speech and noise. Lastly, the N-of-M type of speech coding strategies may select the noise dominated channels instead of the dominant speech...
Source: Hearing Research - February 7, 2013 Category: Audiology Authors: Qazi OU, van Dijk B, Moonen M, Wouters J Tags: Hear Res Source Type: research

Developmental Origin and Fate of Middle Ear Structures.
Abstract Results from developmental and phylogenetic studies have converged to facilitate insight into two important steps in vertebrate evolution: (1) the ontogenetic origin of articulating elements of the buccal skeleton, i.e. jaws, and (2) the later origins of middle ear impedance-matching systems that convey air-borne sound to the inner ear fluids. Middle ear ossicles and other skeletal elements of the viscerocranium (i.e. gill suspensory arches and jaw bones) share a common origin both phylogenetically and ontogenetically. The intention of this brief overview of middle-ear development is to emphasize the inti...
Source: Hearing Research - February 7, 2013 Category: Audiology Authors: Sienknecht UJ Tags: Hear Res Source Type: research

Temporal interaction in electrical hearing elucidates auditory nerve dynamics in humans.
In this study we have developed a double-pulse method and, for the first time, reversed stimulus polarity systematically between consecutive pulses to elucidate subthreshold-induced temporal interaction effects. This method allowed us to determine the time-course of subthreshold temporal interaction in human subjects which identifies the limits of encoded temporal precision. Our results show significant temporal interaction up to 600 μs inter pulse interval. In all the cases tested we saw a facilitation effect on threshold. Interaction effects at a 20% below threshold pre-conditioning stimulation showed up to 38% &plu...
Source: Hearing Research - February 7, 2013 Category: Audiology Authors: Karg SA, Lackner C, Hemmert W Tags: Hear Res Source Type: research

Relations between cochlear histopathology and hearing loss in experimental cochlear implantation.
This study reviews the cochlear histology from four hearing preservation cochlear implantation experiments conducted on 73 guinea pigs from our institution, and relates histopathological findings to residual hearing. All guinea pigs had normal hearing prior to surgery and underwent cochlear implantation via a cochleostomy with a silastic-platinum dummy electrode. Pure tone auditory brainstem response (ABR) thresholds from 2 to 32 kHz were recorded prior to surgery, and at one and four weeks postoperatively. The cochleae were then fixed in paraformaldehyde, decalcified, paraffin embedded, and mid-modiolar sections were...
Source: Hearing Research - February 5, 2013 Category: Audiology Authors: O'Leary SJ, Monksfield P, Kel G, Connolly T, Souter MA, Chang A, Marovic P, O'Leary JS, Richardson R, Eastwood H Tags: Hear Res Source Type: research

Temporal and spatial distribution of gentamicin in the peripheral vestibular system after transtympanic administration in guinea pigs.
CONCLUSION: The saccular uptake of GTTR is greater than other vestibular end-organs after transtympanic injection. In the semi-circular canals. PMID: 23380663 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - February 1, 2013 Category: Audiology Authors: Zhang R, Zhang YB, Dai CF, Steyger PS Tags: Hear Res Source Type: research

Effect of acoustic similarity on short-term auditory memory in the monkey.
Abstract Recent evidence suggests that the monkey's short-term memory in audition depends on a passively retained sensory trace as opposed to a trace reactivated from long-term memory for use in working memory. Reliance on a passive sensory trace could render memory particularly susceptible to confusion between sounds that are similar in some acoustic dimension. If so, then in delayed matching-to-sample, the monkey's performance should be predicted by the similarity in the salient acoustic dimension between the sample and subsequent test stimulus, even at very short delays. To test this prediction and isolate the ...
Source: Hearing Research - January 31, 2013 Category: Audiology Authors: Scott BH, Mishkin M, Yin P Tags: Hear Res Source Type: research

The perceptual enhancement of tones by frequency shifts.
We report here an experiment in which IE and FE were measured using a task requiring the listener to indicate whether or not the second chord included a tone identical to a subsequent probe tone. The results showed that a global attenuation of the first chord relative to the second chord disrupted IE more than FE. This suggests that the mechanisms of IE and FE are not the same. In accordance with this suggestion, computations of the auditory excitation patterns produced by the chords indicate that the mechanism of IE is not sufficient to explain FE for small frequency shifts. PMID: 23376551 [PubMed - as supplied by pu...
Source: Hearing Research - January 31, 2013 Category: Audiology Authors: Demany L, Carcagno S, Semal C Tags: Hear Res Source Type: research

Effects of sensorineural hearing loss on temporal coding of narrowband and broadband signals in the auditory periphery.
This article is part of a Special Issue entitled "Annual Reviews 2013". PMID: 23376018 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - January 29, 2013 Category: Audiology Authors: Henry KS, Heinz MG Tags: Hear Res Source Type: research

Prospects for replacement of auditory neurons by stem cells.
This article is part of a Special Issue entitled "Inner Ear Development and Regeneration". PMID: 23370457 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - January 28, 2013 Category: Audiology Authors: Shi F, Edge AS Tags: Hear Res Source Type: research

Spiral ganglion cell morphology in guinea pigs after deafening and neurotrophic treatment.
Abstract It is well known that spiral ganglion cells (SGCs) degenerate in hair-cell-depleted cochleas and that treatment with exogenous neurotrophins can prevent this degeneration. Several studies reported that, in addition, SGC size decreases after deafening and increases after neurotrophic treatment. The dynamics of these cell size changes are not well known. In a first experiment we measured size, shape (circularity) and intracellular density of SGCs in guinea pigs at various moments after deafening (1, 2, 4, 6, and 8 weeks) and at various cochlear locations. In a second experiment, the effect of treatment with...
Source: Hearing Research - January 26, 2013 Category: Audiology Authors: van Loon MC, Ramekers D, Agterberg MJ, de Groot JC, Grolman W, Klis SF, Versnel H Tags: Hear Res Source Type: research

The mitochondrion: A perpetrator of acquired hearing loss.
This article is part of a Special Issue entitled "Annual Reviews 2013". PMID: 23361190 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - January 26, 2013 Category: Audiology Authors: Böttger EC, Schacht J Tags: Hear Res Source Type: research

Motor Circuits Help Encode Auditory Memories of Vocal Models used to Guide Vocal Learning.
Abstract Early auditory experience can leave a lasting imprint on brain and behavior. This lasting imprint is most notably manifested in culturally transmitted vocal behaviors, including speech and birdsong, where a vocal model heard early in postnatal life exerts a lifelong influence on the individual's vocal repertoire. Because auditory experience of the vocal model can precede accurate vocal imitation by months or even years, a longstanding idea is that a memory of the model is initially stored in auditory centers, and accessed by vocal motor circuits only later in development. This review considers recent evid...
Source: Hearing Research - January 23, 2013 Category: Audiology Authors: Roberts TF, Mooney R Tags: Hear Res Source Type: research

Eustachian tube pressure equilibration. Temporal analysis of pressure changes based on direct physiological recordings with an intact tympanic membrane.
This study employed direct measurements of middle ear pressure in patients, who after parotidectomy had a catheter inserted into the mastoid with a pressure transducer connected. Thus, monitoring of the middle ear pressure in response to experimentally induced pressure changes could be performed under physiological conditions with an intact tympanic membrane. A set of six experiments was performed in four healthy subjects with different pressure deviations, where the counter-regulation was recorded over 10 min's time frames; a total of 75 events of tube openings were recorded. The transducer had a high accuracy of ±...
Source: Hearing Research - January 21, 2013 Category: Audiology Authors: Gaihede M, Padurariu S, Jacobsen H, De Greef D, Dirckx JJ Tags: Hear Res Source Type: research

Rapid measurement of auditory filter shape in mice using the auditory brainstem response and notched noise.
Abstract The notched noise method is an effective procedure for measuring frequency resolution and auditory filter shapes in both human and animal models of hearing. Briefly, auditory filter shape and bandwidth estimates are derived from masked thresholds for tones presented in noise containing widening spectral notches. As the spectral notch widens, increasingly less of the noise falls within the auditory filter and the tone becomes more detectible until the notch width exceeds the filter bandwidth. Behavioral procedures have been used for the derivation of notched noise auditory filter shapes in mice; however, t...
Source: Hearing Research - January 21, 2013 Category: Audiology Authors: Lina IA, Lauer AM Tags: Hear Res Source Type: research

Lead roles for supporting actors: Critical functions of inner ear supporting cells.
Abstract Many studies that aim to investigate the underlying mechanisms of hearing loss or balance disorders focus on the hair cells and spiral ganglion neurons of the inner ear. Fewer studies have examined the supporting cells that contact both of these cell types in the cochlea and vestibular end organs. While the roles of supporting cells are still being elucidated, emerging evidence indicates that they serve many functions vital to maintaining healthy populations of hair cells and spiral ganglion neurons. Here we review recent studies that highlight the critical roles supporting cells play in the development, ...
Source: Hearing Research - January 21, 2013 Category: Audiology Authors: Monzack EL, Cunningham LL Tags: Hear Res Source Type: research

Response properties underlying selectivity for the rate of frequency modulated sweeps in the auditory cortex of the mouse.
This study focused on the response properties underlying selectivity for the rate of frequency modulated (FM) sweeps in the auditory cortex of anesthetized C57bl/6 (C57) mice. Linear downward FM sweeps with rates between 0.08-20 kHz/msec were tested. We show that at least two different response properties predict FM rate selectivity: sideband inhibition and duration tuning. Sideband inhibition was determined using the two-tone inhibition paradigm in which excitatory and inhibitory tones were presented with different delays. Sideband inhibition was present in the majority (88%, n=53) of neurons. The spectrotemporal properti...
Source: Hearing Research - January 19, 2013 Category: Audiology Authors: Trujillo M, Carrasco MM, Razak K Tags: Hear Res Source Type: research

Progressive hereditary hearing impairment caused by a MYO6 mutation resembles presbyacusis.
Abstract Since deafness is the most common sensorineural disorder in humans, better understanding of the underlying causes is necessary to improve counseling and rehabilitation. A Dutch family with autosomal dominantly inherited sensorineural hearing loss was clinically and genetically assessed. The MYO6 gene was selected to be sequenced because of similarities with other, previously described DFNA22 phenotypes and a pathogenic c.3610C>T (p.R1204W) mutation was found to co-segregate with the disease. This missense mutation results in a flat configured audiogram with a mild hearing loss, which becomes severe to ...
Source: Hearing Research - January 19, 2013 Category: Audiology Authors: Oonk AM, Leijendeckers JM, Lammers EM, Weegerink NJ, Oostrik J, Beynon AJ, Huygen PL, Kunst HP, Kremer H, Snik AF, Pennings RJ Tags: Hear Res Source Type: research

Optimal Ossicular Site for Maximal Vibration Transmissions to Coupled Transducers.
In this study, vibrational responses at seven locations on the middle-ear ossicles (i.e., the malleus head, 4 different points on the incus body, middle of the incus long process, tip of the incus long process) in human temporal bones (n=6) were measured using a laser Doppler vibrometer. The measurements were repeated after separating the incudostapedial joint (ISJ). Measured displacement at each location was normalized with the sound pressure level near the tympanic membrane (TM) for representation in the form of a displacement transfer function (DTF). The normalized squared sum of the DTFs (NSSDTF) was then calculated as...
Source: Hearing Research - January 18, 2013 Category: Audiology Authors: Chung J, Song WJ, Sim JH, Kim W, Oh SH Tags: Hear Res Source Type: research

A historical to present-day account of efforts to answer the question, "what puts the brakes on mammalian hair cell regeneration?"
A historical to present-day account of efforts to answer the question, "what puts the brakes on mammalian hair cell regeneration?" Hear Res. 2013 Jan 17; Authors: Burns JC, Corwin JT Abstract Hearing and balance deficits often affect humans and other mammals permanently, because their ears stop producing hair cells within a few days after birth. But production occurs throughout life in the ears of sharks, bony fish, amphibians, reptiles, and birds allowing them to replace lost hair cells and quickly recover after temporarily experiencing the kinds of sensory deficits that are irreversible for mam...
Source: Hearing Research - January 17, 2013 Category: Audiology Authors: Burns JC, Corwin JT Tags: Hear Res Source Type: research

Detection of acoustic temporal fine structure by cochlear implant listeners: Behavioral results and computational modeling.
Abstract A test of within-channel detection of acoustic temporal fine structure (aTFS) cues is presented. Eight cochlear implant listeners (CI) were asked to discriminate between two Schroeder-phase (SP) complexes using a two-alternative, forced-choice task. Because differences between the acoustic stimuli are primarily constrained to their aTFS, successful discrimination reflects a combination of the subjects' perception of and the strategy's ability to deliver aTFS cues. Subjects were mapped with single-channel Continuous Interleaved Sampling (CIS) and Simultaneous Analog Stimulation (SAS) strategies. To compare...
Source: Hearing Research - January 17, 2013 Category: Audiology Authors: Imennov NS, Won JH, Drennan WR, Jameyson E, Rubinstein JT Tags: Hear Res Source Type: research

Dynamic properties of round window membrane in guinea pig otitis media model measured with electromagnetic stimulation.
Abstract The round window, one of two openings into the cochlea from the middle ear, plays an important role in hearing and is known to be structurally altered during otitis media. However, there have been no published studies systematically describing the changes in biomechanical properties of the round window membrane (RWM) that accompany bacterial otitis media. Here we describe the occurrence of significant changes in the dynamic properties of the RWM between normal guinea pigs and those with acute otitis media (AOM) that are detectable by electromagnetic force stimulation and laser Doppler vibrometry (LDV) mea...
Source: Hearing Research - January 16, 2013 Category: Audiology Authors: Gan RZ, Nakmali D, Zhang X Tags: Hear Res Source Type: research

A brief history of hair cell regeneration research and speculations on the future.
This article is part of a Special Issue entitled "Inner Ear Development and Regeneration". PMID: 23321648 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - January 12, 2013 Category: Audiology Authors: Rubel EW, Furrer SA, Stone JS Tags: Hear Res Source Type: research

Masking patterns for monopolar and phantom electrode stimulation in cochlear implants.
Abstract Phantom electrode (PE) stimulation consists of out-of-phase stimulation of two electrodes. When presented at the apex of the electrode array, phantom stimulation is known to produce a lower pitch sensation than monopolar (MP) stimulation on the most apical electrode. The ratio of the current between the primary electrode (PEL) and the compensating electrode (CEL) is represented by the coefficient σ, which ranges from 0 (monopolar) to 1 (full bipolar). The exact mechanism by which PE stimulation produces a lower pitch sensation is unclear. In the present study, unmasked and masked thresholds were obt...
Source: Hearing Research - January 5, 2013 Category: Audiology Authors: Saoji AA, Landsberger DM, Padilla M, Litvak LM Tags: Hear Res Source Type: research