Auditory Characters Research Articles

Pathological mechanisms of connexin26-related hearing loss: Potassium recycling, ATP-calcium signaling, or energy supply?

Hereditary deafness is one of the most common human birth defects. GJB2 gene mutation is the most genetic etiology. Gap junction protein 26 (connexin26, Cx26) encoded by the GJB2 gene, which is responsible for intercellular substance transfer and signal communication, plays a critical role in hearing acquisition and maintenance. The auditory character of different Connexin26 transgenic mice models can be classified into two types: profound congenital deafness and late-onset progressive hearing loss. Recent studies demonstrated that there are pathological changes including endocochlear potential reduction, active cochlear amplification impairment, cochlear developmental disorders, and so on, in connexin26 deficiency mice. Here, this review summarizes three main hypotheses to explain pathological mechanisms of connexin26-related hearing loss: potassium recycling disruption, adenosine-triphosphate-calcium signaling propagation disruption, and energy supply dysfunction. Elucidating pathological mechanisms underlying connexin26-related hearing loss can help develop new protective and therapeutic strategies for this common deafness. It is worthy of further study on the detailed cellular and molecular upstream mechanisms to modify connexin (channel) function.

From Land to the Water: A Comparative Look at the Morphologies of the Auditory Apparatuses of Carnivores

Morphological characters have been the basis for determining evolutionary relationships among mammalian carnivores and continue to be important in that regard. For the animals that make up the families Phocidae (true seals), Otariidae (sea lions and fur seals), and Odobenidae (walruses), together known as Pinnipedia, the research is very limited on the morphology of their auditory apparatuses. In regard to the few auditory characters that are well studied, they are almost always used for phylogenetic analyses. The reasoning behind their use in these analyses is that there is disagreement as to how pinnipeds evolved: do pinnipeds have a monophyletic or a diphyletic origin? To aide in answering this overall question of phylogeny this study plans to establish the morphology of characters of the auditory region and surrounding basicrania, to determine some of the processes in which auditory characters evolved due to a return to water, and if any of these characters have a phylogenetic signal. Some of the preliminary results include some osteological measurements of both extinct and extant specimens and CT scans of specific semiaquatic carnivoran skulls. One of the CT scans included the extinct seal Devinophoca emryi (early‐middle Miocene, ~16 Ma), which is known to have a mixture of primitive and derived characters in the skull and postcrania. Preliminary observation of the basicranium and auditory region demonstrates a mixture of primitive and derived characters as well. Overall, the comparative morphology of Pinnipedia ossicles and other derived auditory characters can possibly retain high phylogenetic signal even with the adaptive pressures of the aquatic environment. This information will aid in the overall understanding of phocid evolution and hearing adaptation during the transition from land to water.

Tinnitus - Clinical Symptoms and Therapy

Tinnitus is a phantom sound that can be a symptom of various disorders such as hearing loss, cardiovascular diseases, neurological disorders, diabetes or tumors. Because of the inability to divert the auditory attention from tinnitus sound, patients suffer with insomnia, problems with concentration and other psychological conditions, in some extreme cases including major depression symptoms. The auditory character of tinnitus induces the patients to seek help predominantly at the otolaryngologist practice. The first aim of a physician is to establish the cause of tinnitus and to measure its audiological properties. The second aim is to estimate the tinnitus-induced distress and to grade its psychological severity. This manuscript is dedicated to describe the audiological as well as psychological properties of tinnitus, its contemporary classification and the therapeutic methods used in the field.

Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

New isolated petrosals from the Itaborai beds of Brazil (late Palaeocene or early Eocene) are here described and referred to the early diverging litoptern Miguelsoria parayirunhor, based on phylogenetic, size, and abundance arguments. Both the external and internal anatomy of these specimens were investigated, which for the first time document many details of the auditory region of a Palaeogene litoptern. Our cladistic analysis, which included our new observations, failed to recover a monophyletic Litopterna but did not exclude it. A constrained analysis for the monophyly of this order showed that several features such as a (sub)quadrangular and anteroposteriorly elongated tensor tympani fossa and a large notch in the vicinity of the external opening of the cochlear canaliculus may constitute synapomorphies for Litopterna. The evolution of several other auditory characters amongst Litopterna is discussed and the relative dimensions of the inner ear and surrounding petrosal in the group were also investigated. This allowed detection of negative allometry of the bony labyrinth within the petrosal, which was confirmed by measurements and regression analysis across a larger sample of placental mammals. This scaling effect probably has an important influence on several characters of the bony labyrinth and petrosal, amongst which are the length of the vestibular aqueduct and cochlear canaliculus. It demonstrates that many aspects of the morphological variation of the bony labyrinth need to be thoroughly investigated before being incorporated into phylogenetic analyses. © 2015 The Linnean Society of London

A Comparison of Ambient Casino Sound and Music: Effects on Dissociation and on Perceptions of Elapsed Time While Playing Slot Machines

This research examined the effects of a casino's auditory character on estimates of elapsed time while gambling. More specifically, this study varied whether the sound heard while gambling was ambient casino sound alone or ambient casino sound accompanied by music. The tempo and volume of both the music and ambient sound were varied to manipulate temporal engagement and introspection. One hundred and sixty (males = 91) individuals played slot machines in groups of 5-8, after which they provided estimates of elapsed time. The findings showed that the typical ambient casino auditive environment, which characterizes the majority of gaming venues, promotes understated estimates of elapsed duration of play. In contrast, when music is introduced into the ambient casino environment, it appears to provide a cue of interval from which players can more accurately reconstruct elapsed duration of play. This is particularly the case when the tempo of the music is slow and the volume is high. Moreover, the confidence with which time estimates are held (as reflected by latency of response) is higher in an auditive environment with music than in an environment that is comprised of ambient casino sounds alone. Implications for casino management are discussed.

The suppression of reflexive visual and auditory orienting when attention is otherwise engaged.

Two experiments were conducted to examine whether abrupt onsets are capable of reflexively capturing attention when they occur outside the current focus of spatial attention, as would be expected if exogenous orienting operates in a truly automatic fashion. The authors established a highly focused attentional state by means of the central presentation of a stream of visual or auditory characters, which participants sometimes had to monitor. No intramodal reflexive cuing effects were observed in either audition or vision when participants performed either an exogenous visual or auditory orthogonal cuing task together with the central focused attention task. These results suggest that reflexive unimodal orienting is not truly automatic. The fact that cuing effects were eliminated under both unimodal and cross-modal conditions is consistent with the view that auditory and visual reflexive spatial orienting are controlled by a common underlying neural substrate.

Morphometrics and Functional Morphology of Middle Ears of Extant Pocket Gophers (Rodentia: Geomyidae)

The 11 species of pocket gophers (Geomys bursarius, G. personatus, G. pine tis G. texensis, Thomomys bottae, T. bulbivorus, T. talpoides, Pappogeomys bulleri, P. castanops, Crato­ geomys tylorhinus, Orthogeomys heterodus) that we examined exhibit a distinctive suite of auditory characters: otic capsule of thick trabecular bone, a bone-encased stapedial artery having a very narrow lumen (except in P. bulleri), absence of the stapedius muscle, and most notably a stapes with a highly convex hollow footplate that protrudes into the vestibule of the inner ear. Qualitatively, all species of pocket gophers that we examined were similar. Quantitatively, there was little intraspecific variation in meristic features with regard to sex, but ontogenetic variation was significant with most features increasing in size with increas­ ing skull dimensions. Interspecifically, measured auditory features scaled positively with condylobasal length. For most functional auditory features (e.g., areal ratios, lever-arm ratios), intraspecific (sex or age) and interspecific variations were insignificant. The peculiar morphology of geomyid ears might serve a protective function in the noisy subterranean setting. Alternatively, novel features of the geomyid ear simply might be the result of heterochrony. Hyrtl's (1845) treatise on auditory mor­ phology in an array of mammalian species constituted the first report of a stapedial footplate possessing an unusual bullate form. In this configuration, the footplate, rather than being fiat, bulges convexly far into the vestibule of the inner ear. Hyrtl (1845) reported this morphology for the ring-tailed possum Phalangista cookii (= Pseudocheirus peregrinus; Petauridae), a scansorial arboreal marsupial (Nowak and Paradiso, 1983). Subsequent anatomical in­ vestigations revealed the highly convex sta­ pedial footplate in only two other families of mammals, Geomyidae and Heteromyi­ dae. Geomyids are highly fossorial herbiv­ orous rodents occurring in North and Cen

Determinants of ganglion-receptor cell interaction during development of the inner ear. A heterochronic ganglia study.

It has been suggested that inner ear sensory receptors produce attractant fields that guide neurite outgrowth from statoacoustic ganglion (SAG) neurons to appropriate target sites within the developing labyrinth. This experiment tested the temporal limitations of SAG neurons in their ability to respond to these attractant fields. Statoacoustic ganglia were excised from 12, 13, 14 and 15 gestation day (GD) mouse embryos. This temporal series of SAG was implanted into aganglionic 12 GD otocysts. All cultures were grown for 7 days in vitro, then fixed and processed for nerve fiber staining. Specimens were evaluated for the presence of neurites associated with the inner ear sensory receptors that developed within the otic explants. All of the implanted heterochronic ganglia (i.e. 13, 14 or 15 GD) as well as the homochronic (i.e. 12 GD) ganglion controls extended neurites to sensory epithelium of both vestibular and auditory character. Neurites made contact with the base of hair cells in all of the sensory structures. These findings demonstrate that SAG neurons are capable of extending processes in response to otic attractant fields for an extended period during the embryonic development of this ganglion. This observation supports the hypothesis that the onset and duration of receptor generated attractant fields may act as a controlling factor in establishing patterns of innervation within the developing inner ear.

Neuron-receptor Cell Interaction during Development of the Inner EarA Heterochronic Ganglion Study

It has been proposed that inner ear sensory receptors produce attractant fields which act to guide neuritic elements of the statoacoustic ganglia (SAG) to their appropriate target sites (Van De Water and Ruben, Acta Otolaryngol. 95: 470-479, 1983). This experiment tests the ability of the neurons of a staged series of statoacoustic ganglia to extend neuritic processes in response to the attractant fields produced by differentiating inner ear sensory epithelia. A previous study of the developing mouse inner ear (Sher, Acta Otolaryngol. Suppl. 285: 1-77, 1971) has shown that neuritic elements of the statoacoustic ganglion begin to actively extend their processes to peripheral target sites on the 12th day of gestation (12 GD). Therefore, an aneural 12 GD otocyst was used as the target tissue source for all of the heterochronic ganglia implants. Statoacoustic ganglia were removed from 12,13,14 and 15 GD mouse inner ears and then implanted into the aganglionic 12 GD otic explants prior to explantation to in vitro. All cultures were grown for a period of 7 days in vitro. At the end of the culture period, the 12 GD otocyst explants with their implanted homo and heterochronic SAG were fixed and processed for nerve fiber staining by the Bodian technique. Specimens were examined by light microscopy and evaluated for the presence of SAG nerve fibers projecting from the implanted ganglia to both vestibular and auditory sensory receptors that developed within the explants. The results show that SAG neurons of the implanted homochronic (i.e. 12 GD SAG/12 GD OTOCYST) and all heterochronic ganglia (i.e. 13, 14 or 15 GD SAG/12 GD OTOCYST) extended neuritic processes to the areas of developing sensory epithelium of both vestibular and auditory character. Nerve fibers were present in association with sensory hair cells of cristae, maculae and organ of Corti sensory receptors. These fibers made contact with the bases of the sensory hair cells in all of the sensory structures studied. Ultrastructural studies are in progress that will determine the nature of the sensory cell/nerve fiber association in both the homo and heterochronic SAG implants of these cultures and compare them to an equivalent level of in utero development (i.e. 19 GD) of the mouse inner ear.The results of this study demonstrate that the neurons which compose the murine statoacoustic ganglion are capable of extending neuritic processes to attractant fields produced by areas of differentiating otic sensory epithelia for an extended period (i.e. 12-15 GD) during the development of this ganglion. These findings support the hypothesis that the onset and duration of the receptor generated attractant fields may act as a controlling factor in establishing patterns of innervation within the developing inner ear.

Sideways look at dichotic listening

The present experiment investigates the possibility that performance on the dichotic listening task is systematically influenced by variables unrelated to the linguistic or auditory character of the stimuli employed. Subjects sat in a lighted room with head position fixed and listened to a standard dichotic CV tape. Binocular Risley prisms were used to displace the subjects' visual environment either 13° to the left, 13° to the right, or not at all. A right ear advantage was obtained in the no-displacement condition (percentage of correct responses contributed by the right ear—POC—was 55.5%). This advantage was decreased in the left-displacement condition (POC = 51.8%) and was increased in the right-displacement condition (POC = 57.1%). This result indicates that subjects' performance on the dichotic listening task may reflect a number of psychological and physiological factors, in addition to a possible cortical hemispheric specialization for language. Among the factors considered are attention (of an involuntary sort) and spatial orientation mechanisms normally involved in sound localization and binaural fusion.