As sensory cells, hair cells within the mammalian inner ear convert sounds into receptor potentials when their projecting stereocilia are deflected. The organ of Corti of the cochlea contains two types of hair cell, inner and outer hair cells, which differ in function. It has been appreciated for over two decades that although inner hair cells act as the primary receptor cell for the auditory s...

Despite the fact that mammalian hair cells and neurons do not naturally regenerate in vivo, progenitor cells exist within the postnatal inner ear that can be manipulated to generate hair cells and neurons. This work reveals the differentiation capabilities of distinct inner ear progenitor populations and pinpoints cell types that can become cochlear hair cells, vestibular hair cells, neurons, a...

Thyroid hormone acts on gene transcription by binding to its nuclear receptors TRα1 and TRβ. Whereas global deletion of TRβ causes deafness, global TRα-deficient mice have normal hearing thresholds. Since the individual roles of the two receptors in cochlear hair cells are still unclear, we generated mice with a hair cell-specific mutation of TRα1 or deletion of TRβ using the Cre-loxP system. H...

Noise overstimulation can induce loss of synaptic ribbons associated with loss of Inner Hair Cell - Auditory Nerve synaptic connections. This study examined if systemic administration of Piribedil, a dopamine agonist that reduces the sound evoked auditory nerve compound action potential and/or Memantine, an NMDA receptor open channel blocker, would reduce noise-induced loss of Inner Hair Cell r...

Sensory hair cells of the inner ear express multiple physiologically defined conductances, including mechanotransduction, Ca(2+), Na(+), and several distinct K(+) conductances, all of which are critical for normal hearing and balance function. Yet, the molecular underpinnings and their specific contributions to sensory signaling in the inner ear remain obscure. We sought to identify hair-cell c...

PURPOSE OF REVIEW This review covers the articles published between 2010 and early 2011 that presented new findings on inner-ear efferents and their ability to modulate hair cell function. RECENT FINDINGS Studies published within the review period have increased our understanding of efferent mechanisms on hair cells in the cochlear and vestibular sensory epithelium and provide insights on eff...

In the mouse, Frizzled3 (Fz3) and Frizzled6 (Fz6) have been shown previously to control axonal growth and guidance in the CNS and hair patterning in the skin, respectively. Here, we report that Fz3 and Fz6 redundantly control neural tube closure and the planar orientation of hair bundles on a subset of auditory and vestibular sensory cells. In the inner ear, Fz3 and Fz6 proteins are localized t...

we compared the extent of temporary threshold shift (tts) and hair cell loss following high level 4 khz noise exposure with those preconditioned with moderate level 1 and 4 khz octave band noise. fifteen male albino guinea pigs (300- 350 g in weight) were randomly allocated into three groups: those exposed to 4 khz octave band noise at 102 db spl (group 1, n=5); those conditioned with 1 khz oct...

Hair cell degeneration and the repair process due to differing types of trauma have been studied extensively in the organ of Corti. It has been determined that, during scar formation, after differing types of trauma to the auditory sensory system, the reticular lamina is maintained with adherens junctions and tight junctions. We investigated the repair process within the vestibular epithelium. ...

Usher syndrome 3A (USH3A) is an autosomal recessive disorder characterized by progressive loss of hearing and vision due to mutation in the clarin-1 (CLRN1) gene. Lack of an animal model has hindered our ability to understand the function of CLRN1 and the pathophysiology associated with USH3A. Here we report for the first time a mouse model for ear disease in USH3A. Detailed evaluation of inner...