Browsing by Subject "Hearing"
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Item Open Access Anatomical and Functional Consequences of Microneedle Perforation of Round Window Membrane.(Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology, 2020-02) Yu, Michelle; Arteaga, Daniel N; Aksit, Aykut; Chiang, Harry; Olson, Elizabeth S; Kysar, Jeffrey W; Lalwani, Anil KHypothesis
Microneedles can create microperforations in the round window membrane (RWM) without causing anatomic or physiologic damage.Background
Reliable delivery of agents into the inner ear for therapeutic and diagnostic purposes remains a challenge. Our novel approach employs microneedles to facilitate intracochlear access via the RWM. This study investigates the anatomical and functional consequences of microneedle perforations in guinea pig RWMs in vivo.Methods
Single three-dimensional-printed, 100 μm diameter microneedles were used to perforate the guinea pig RWM via the postauricular sulcus. Hearing was assessed both before and after microneedle perforation using compound action potential and distortion product otoacoustic emissions. Confocal microscopy was used ex vivo to examine harvested RWMs, measuring the size, shape, and location of perforations and documenting healing at 0 hours (n = 7), 24 hours (n = 6), 48 hours (n = 6), and 1 week (n = 6).Results
Microneedles create precise and accurate perforations measuring 93.1 ± 29.0 μm by 34.5 ± 16.8 μm and produce a high-frequency threshold shift that disappears after 24 hours. Examination of perforations over time demonstrates healing progression over 24 to 48 hours and complete perforation closure by 1 week.Conclusion
Microneedles can create a temporary microperforation in the RWM without causing significant anatomic or physiologic dysfunction. Microneedles have the potential to mediate safe and effective intracochlear access for diagnosis and treatment of inner ear disease.Item Open Access Association Between Hearing Handicap and Life-Space Mobility in a Patient Population.(American journal of audiology, 2023-06) Oliva, Allison; West, Jessica S; Smith, Sherri L; Huang, Ryan J; Riska, Kristal MPurpose
The purpose of this study was to evaluate the association between self-reported hearing handicap and life-space mobility utilizing the Life-Space Questionnaire (LSQ). Life-space mobility reflects how an individual moves through their daily physical and social environment, and the role of hearing loss in life-space mobility is not fully understood. We hypothesized that those with higher self-reported hearing handicap would be more likely to demonstrate restricted life-space mobility.Method
A total of 189 older adults (M age = 75.76 years, SD = 5.81) completed a mail-in survey packet including the LSQ and Hearing Handicap Inventory for the Elderly (HHIE). Participants were categorized into one of three groups ("no/none," "mild/moderate," or "severe" hearing handicap) according to HHIE total score. LSQ responses were dichotomized to either "nonrestricted/typical" or "restricted" life-space mobility groups. Logistic regression models were performed to analyze life-space mobility differences among the groups.Results
Logistic regression results demonstrated no statistically significant association between hearing handicap and LSQ.Conclusions
The results of this study indicate that there is no association between self-reported hearing handicap and life-space mobility as evaluated using a mail-in version of the LSQ. This counters other studies that have demonstrated that life space is associated with chronic illness, cognitive functioning, and social and health integration.Item Open Access Auditory morphology and hearing sensitivity in fossil New World monkeys.(Anatomical record (Hoboken, N.J. : 2007), 2010-10) Coleman, M; Kay, RF; Colbert, MWIn recent years it has become possible to investigate the hearing capabilities in fossils by analogy with studies in living taxa that correlate the bony morphology of the auditory system with hearing sensitivity. In this analysis, we used a jack-knife procedure to test the accuracy of one such study that examined the functional morphology of the primate auditory system and we found that low-frequency hearing (sound pressure level at 250 Hz) can be predicted with relatively high confidence (±3-8 dB depending on the structure). Based on these functional relationships, we then used high-resolution computed tomography to examine the auditory region of three fossil New World monkeys (Homunculus, Dolicocebus, and Tremacebus) and compared their morphology and predicted low-frequency sensitivity with a phylogenetically diverse sample of extant primates. These comparisons reveal that these extinct taxa shared many auditory characteristics with living platyrrhines. However, the fossil with the best preserved auditory region (Homunculus) also displayed a few unique features such as the relative size of the tympanic membrane and stapedial footplate and the degree of trabeculation of the anterior accessory cavity. Still, the majority of evidence suggests that these fossil species likely had similar low-frequency sensitivity to extant South American monkeys. This research adds to the small but growing body of evidence on the evolution of hearing abilities in extinct taxa and lays the groundwork for predicting hearing sensitivity in additional fossil primate specimens.Item Open Access Early Physiological and Cellular Indicators of Cisplatin-Induced Ototoxicity.(Journal of the Association for Research in Otolaryngology : JARO, 2021-04) Chen, Yingying; Bielefeld, Eric C; Mellott, Jeffrey G; Wang, Weijie; Mafi, Amir M; Yamoah, Ebenezer N; Bao, JianxinCisplatin chemotherapy often causes permanent hearing loss, which leads to a multifaceted decrease in quality of life. Identification of early cisplatin-induced cochlear damage would greatly improve clinical diagnosis and provide potential drug targets to prevent cisplatin's ototoxicity. With improved functional and immunocytochemical assays, a recent seminal discovery revealed that synaptic loss between inner hair cells and spiral ganglion neurons is a major form of early cochlear damage induced by noise exposure or aging. This breakthrough discovery prompted the current study to determine early functional, cellular, and molecular changes for cisplatin-induced hearing loss, in part to determine if synapse injury is caused by cisplatin exposure. Cisplatin was delivered in one to three treatment cycles to both male and female mice. After the cisplatin treatment of three cycles, threshold shift was observed across frequencies tested like previous studies. After the treatment of two cycles, beside loss of outer hair cells and an increase in high-frequency hearing thresholds, a significant latency delay of auditory brainstem response wave 1 was observed, including at a frequency region where there were no changes in hearing thresholds. The wave 1 latency delay was detected as early cisplatin-induced ototoxicity after only one cycle of treatment, in which no significant threshold shift was found. In the same mice, mitochondrial loss in the base of the cochlea and declining mitochondrial morphometric health were observed. Thus, we have identified early spiral ganglion-associated functional and cellular changes after cisplatin treatment that precede significant threshold shift.Item Open Access For whom the bird sings: context-dependent gene expression.(Neuron, 1998-10) Jarvis, ED; Scharff, C; Grossman, MR; Ramos, JA; Nottebohm, FMale zebra finches display two song behaviors: directed and undirected singing. The two differ little in the vocalizations produced but greatly in how song is delivered. "Directed" song is usually accompanied by a courtship dance and is addressed almost exclusively to females. "Undirected" song is not accompanied by the dance and is produced when the male is in the presence of other males, alone, or outside a nest occupied by its mate. Here, we show that the anterior forebrain vocal pathway contains medial and lateral "cortical-basal ganglia" subdivisions that have differential ZENK gene activation depending on whether the bird sings female-directed or undirected song. Differences also occur in the vocal output nucleus, RA. Thus, although these two vocal behaviors are very similar, their brain activation patterns are dramatically different.Item Open Access Learned birdsong and the neurobiology of human language.(Ann N Y Acad Sci, 2004-06) Jarvis, Erich DVocal learning, the substrate for human language, is a rare trait found to date in only three distantly related groups of mammals (humans, bats, and cetaceans) and three distantly related groups of birds (parrots, hummingbirds, and songbirds). Brain pathways for vocal learning have been studied in the three bird groups and in humans. Here I present a hypothesis on the relationships and evolution of brain pathways for vocal learning among birds and humans. The three vocal learning bird groups each appear to have seven similar but not identical cerebral vocal nuclei distributed into two vocal pathways, one posterior and one anterior. Humans also appear to have a posterior vocal pathway, which includes projections from the face motor cortex to brainstem vocal lower motor neurons, and an anterior vocal pathway, which includes a strip of premotor cortex, the anterior basal ganglia, and the anterior thalamus. These vocal pathways are not found in vocal non-learning birds or mammals, but are similar to brain pathways used for other types of learning. Thus, I argue that if vocal learning evolved independently among birds and humans, then it did so under strong genetic constraints of a pre-existing basic neural network of the vertebrate brain.Item Open Access Molecular mapping of brain areas involved in parrot vocal communication.(J Comp Neurol, 2000-03-27) Jarvis, ED; Mello, CVAuditory and vocal regulation of gene expression occurs in separate discrete regions of the songbird brain. Here we demonstrate that regulated gene expression also occurs during vocal communication in a parrot, belonging to an order whose ability to learn vocalizations is thought to have evolved independently of songbirds. Adult male budgerigars (Melopsittacus undulatus) were stimulated to vocalize with playbacks of conspecific vocalizations (warbles), and their brains were analyzed for expression of the transcriptional regulator ZENK. The results showed that there was distinct separation of brain areas that had hearing- or vocalizing-induced ZENK expression. Hearing warbles resulted in ZENK induction in large parts of the caudal medial forebrain and in 1 midbrain region, with a pattern highly reminiscent of that observed in songbirds. Vocalizing resulted in ZENK induction in nine brain structures, seven restricted to the lateral and anterior telencephalon, one in the thalamus, and one in the midbrain, with a pattern partially reminiscent of that observed in songbirds. Five of the telencephalic structures had been previously described as part of the budgerigar vocal control pathway. However, functional boundaries defined by the gene expression patterns for some of these structures were much larger and different in shape than previously reported anatomical boundaries. Our results provide the first functional demonstration of brain areas involved in vocalizing and auditory processing of conspecific sounds in budgerigars. They also indicate that, whether or not vocal learning evolved independently, some of the gene regulatory mechanisms that accompany learned vocal communication are similar in songbirds and parrots.Item Open Access Optimizing non-invasive functional markers for cochlear deafferentation based on electrocochleography and auditory brainstem responses.(The Journal of the Acoustical Society of America, 2022-04) Harris, Kelly C; Bao, JianxinAccumulating evidence suggests that cochlear deafferentation may contribute to suprathreshold deficits observed with or without elevated hearing thresholds, and can lead to accelerated age-related hearing loss. Currently there are no clinical diagnostic tools to detect human cochlear deafferentation in vivo. Preclinical studies using a combination of electrophysiological and post-mortem histological methods clearly demonstrate cochlear deafferentation including myelination loss, mitochondrial damages in spiral ganglion neurons (SGNs), and synaptic loss between inner hair cells and SGNs. Since clinical diagnosis of human cochlear deafferentation cannot include post-mortem histological quantification, various attempts based on functional measurements have been made to detect cochlear deafferentation. So far, those efforts have led to inconclusive results. Two major obstacles to the development of in vivo clinical diagnostics include a lack of standardized methods to validate new approaches and characterize the normative range of repeated measurements. In this overview, we examine strategies from previous studies to detect cochlear deafferentation from electrocochleography and auditory brainstem responses. We then summarize possible approaches to improve these non-invasive functional methods for detecting cochlear deafferentation with a focus on cochlear synaptopathy. We identify conceptual approaches that should be tested to associate unique electrophysiological features with cochlear deafferentation.Item Open Access Sensory-motor transformations for speech occur bilaterally.(Nature, 2014-03-06) Cogan, Gregory B; Thesen, Thomas; Carlson, Chad; Doyle, Werner; Devinsky, Orrin; Pesaran, BijanHistorically, the study of speech processing has emphasized a strong link between auditory perceptual input and motor production output. A kind of 'parity' is essential, as both perception- and production-based representations must form a unified interface to facilitate access to higher-order language processes such as syntax and semantics, believed to be computed in the dominant, typically left hemisphere. Although various theories have been proposed to unite perception and production, the underlying neural mechanisms are unclear. Early models of speech and language processing proposed that perceptual processing occurred in the left posterior superior temporal gyrus (Wernicke's area) and motor production processes occurred in the left inferior frontal gyrus (Broca's area). Sensory activity was proposed to link to production activity through connecting fibre tracts, forming the left lateralized speech sensory-motor system. Although recent evidence indicates that speech perception occurs bilaterally, prevailing models maintain that the speech sensory-motor system is left lateralized and facilitates the transformation from sensory-based auditory representations to motor-based production representations. However, evidence for the lateralized computation of sensory-motor speech transformations is indirect and primarily comes from stroke patients that have speech repetition deficits (conduction aphasia) and studies using covert speech and haemodynamic functional imaging. Whether the speech sensory-motor system is lateralized, like higher-order language processes, or bilateral, like speech perception, is controversial. Here we use direct neural recordings in subjects performing sensory-motor tasks involving overt speech production to show that sensory-motor transformations occur bilaterally. We demonstrate that electrodes over bilateral inferior frontal, inferior parietal, superior temporal, premotor and somatosensory cortices exhibit robust sensory-motor neural responses during both perception and production in an overt word-repetition task. Using a non-word transformation task, we show that bilateral sensory-motor responses can perform transformations between speech-perception- and speech-production-based representations. These results establish a bilateral sublexical speech sensory-motor system.