Ear | EPFL Graph Search

An ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In mammals the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization. The ear develops from the fir

Intravital Immunofluorescence for Visualizing the Microcirculatory and Immune Microenvironments in the Mouse Ear Dermis

Witold Waldemar Kilarski, Amanda Waite Lund, Scott Oliver, Melody Swartz, Jeremy Teo

Visualizing the dynamic behaviors of immune cells in living tissue has dramatically increased our understanding of how cells interact with their surroundings, contributing important insights into mechanisms of leukocyte trafficking, tumor cell invasion, and T cell education by dendritic cells, among others. Despite substantial advances with various intravital imaging techniques including two-photon microscopy and the generation of multitudes of reporter mice, there is a growing need to assess cell interactions in the context of specific extracellular matrix composition and microvascular functions, and as well, simpler and more widely accessible methods are needed to image cell behaviors in the context of living tissue physiology. Here we present an antibody-based method for intravital imaging of cell interactions with the blood, lymphatic, and the extracellular matrix compartments of the living dermis while simultaneously assessing capillary permeability and lymphatic drainage function. Using the exposed dorsal ear of the anesthetized mouse and a fluorescence stereomicroscope, such events can be imaged in the context of specific extracellular matrix proteins, or matrix-bound chemokine stores. We developed and optimized the method to minimize tissue damage to the ear, rapidly immunostain for multiple extracellular or cell surface receptors of interest, minimize immunotoxicity with pre-blocking Fc gamma receptors and phototoxicity with extracellular antioxidants, and highlight the major dermal tissue structures with basement membrane markers. We demonstrate differential migration behaviors of bone marrow-derived dendritic cells, blood-circulating leukocytes, and dermal dendritic cells, with the latter entering sparse CCL21-positive areas of pre-collecting lymphatic vessels. This new method allows simultaneous imaging of cells and tissue structures, microvascular function, and extracellular microenvironment in multiple skin locations for 12 hours or more, with the flexibility of immunolabeling in addition to genetic-based fluorescent reporters.

Public Library of Science2013

Active Control mitigating the Ear Canal Occlusion Effect caused by Hearing Aids

Thomas Stefan Zurbrügg

The World Health Organization (WHO) estimates the prevalence of a disabling hearing loss to be above 5% world-wide 1. A treatment with a hearing aid - be it behind-the-ear (BTE), in-the-ear (ITE) or receiver-in-canal (RIC) - involves some degree of occlusion of the external ear canal. In many cases, this so-called occlusion effect (OE) leads to an unfamiliar perception of the hearing aid user’s own voice. This fact represents a limiting factor regarding the acceptance of hearing aids by potential users. This thesis focuses on modeling the physical occlusion effect caused by hearing aids and the investigation of active control approaches mitigating this adverse effect. A simple model based on audiological transfer functions is presented, discussed and validated in the first part of the thesis. This model is subsequently used as a basis for the analysis and the synthesis of an active control approach based on sound pressure feedback. The objective and subjective validation of this approach implemented as a prototype setup in a user-study is presented. Finally, the use of the insights from the first part for fitting a hearing aid incorporating such active occlusion control is suggested.

EPFL2014

Study of tonotopic brain changes with functional MRI and FDG-PET in a patient with unilateral objective cochlear tinnitus

Melissa Saenz

We studied possible brain changes with functional MRI (fMRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) in a patient with a rare, high-intensity "objective tinnitus" (high-level SOAEs) in the left ear of 10 years duration, with no associated hearing loss. This is the first case of objective cochlear tinnitus to be investigated with functional neuroimaging. The objective cochlear tinnitus was measured by Spontaneous Otoacoustic Emissions (SOAE) equipment (frequency 9689 Hz, intensity 57 dB SPL) and is clearly audible to anyone standing near the patient. Functional modifications in primary auditory areas and other brain regions were evaluated using 3T and 7T fMRI and FDG-PET. In the fMRI evaluations, a saturation of the auditory cortex at the tinnitus frequency was observed, but the global cortical tonotopic organization remained intact when compared to the results of fMRI of healthy subjects. The FDG-PET showed no evidence of an increase or decrease of activity in the auditory cortices or in the limbic system as compared to normal subjects. In this patient with high-intensity objective cochlear tinnitus, fMRI and FDG-PET showed no significant brain reorganization in auditory areas and/or in the limbic system, as reported in the literature in patients with chronic subjective tinnitus.

Elsevier2016

Intravital Immunofluorescence for Visualizing the Microcirculatory and Immune Microenvironments in the Mouse Ear Dermis

Witold Waldemar Kilarski, Amanda Waite Lund, Scott Oliver, Melody Swartz, Jeremy Teo

Public Library of Science2013