Simulation of the efficiency of inner hair cell secretion in the auditory pathway

2019 ◽  
Author(s):  
J. Soto ◽  
N. Castaneda-Villa ◽  
A. Gil ◽  
V. Gonzalez-Velez
Keyword(s):  
Hair Cell ◽  
Auditory Pathway ◽  
Inner Hair Cell ◽  
Cell Secretion

scholarly journals Dendritic HCN Channels Shape Excitatory Postsynaptic Potentials at the Inner Hair Cell Afferent Synapse in the Mammalian Cochlea

2010 ◽  
Vol 103 (5) ◽  
pp. 2532-2543 ◽  
Author(s):  
Eunyoung Yi ◽  
Isabelle Roux ◽  
Elisabeth Glowatzki
Keyword(s):  
Hair Cell ◽  
Auditory Pathway ◽  
Nerve Fibers ◽  
Intracellular Camp ◽  
Hcn Channels ◽  
Excitatory Postsynaptic Potentials ◽  
Inner Hair Cell ◽  
Postsynaptic Potentials ◽  
Afferent Synapse ◽  
Reliable Signaling

Synaptic transmission at the inner hair cell (IHC) afferent synapse, the first synapse in the auditory pathway, is specialized for rapid and reliable signaling. Here we investigated the properties of a hyperpolarization-activated current ( Ih), expressed in the afferent dendrite of auditory nerve fibers, and its role in shaping postsynaptic activity. We used whole cell patch-clamp recordings from afferent dendrites directly where they contact the IHC in excised postnatal rat cochlear turns. Excitatory postsynaptic potentials (EPSPs) of variable amplitude (1–35 mV) were found with 10–90% rise times of about 1 ms and time constants of decay of about 5 ms at room temperature. Current–voltage relations recorded in afferent dendrites revealed Ih. The pharmacological profile and reversal potential (−45 mV) indicated that Ih is mediated by hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels. The HCN channel subunits HCN1, HCN2, and HCN4 were found to be expressed in afferent dendrites using immunolabeling. Raising intracellular cAMP levels sped up the activation kinetics, increased the magnitude of Ih and shifted the half activation voltage ( Vhalf) to more positive values (−104 ± 3 to −91 ± 2 mV). Blocking Ih with 50 μM ZD7288 resulted in hyperpolarization of the resting membrane potential (∼4 mV) and slowing the decay of the EPSP by 47%, suggesting that Ih is active at rest and shortens EPSPs, thereby potentially improving rapid and reliable signaling at this first synapse in the auditory pathway.

scholarly journals Inner hair cell stereocilia are embedded in the tectorial membrane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Hakizimana ◽  
Anders Fridberger
Keyword(s):  
Electron Microscopy ◽  
Hair Cell ◽  
Mechanical Stimulation ◽  
Hair Cells ◽  
Viscous Drag ◽  
Tectorial Membrane ◽  
Inner Hair Cell ◽  
Inner Hair Cells ◽  
Inward Currents

AbstractMammalian hearing depends on sound-evoked displacements of the stereocilia of inner hair cells (IHCs), which cause the endogenous mechanoelectrical transducer channels to conduct inward currents of cations including Ca2+. Due to their presumed lack of contacts with the overlaying tectorial membrane (TM), the putative stimulation mechanism for these stereocilia is by means of the viscous drag of the surrounding endolymph. However, despite numerous efforts to characterize the TM by electron microscopy and other techniques, the exact IHC stereocilia-TM relationship remains elusive. Here we show that Ca2+-rich filamentous structures, that we call Ca2+ ducts, connect the TM to the IHC stereocilia to enable mechanical stimulation by the TM while also ensuring the stereocilia access to TM Ca2+. Our results call for a reassessment of the stimulation mechanism for the IHC stereocilia and the TM role in hearing.

Free radical scavenger protects against inner hair cell loss after cochlear ischemia

Neuroreport ◽  
2003 ◽  
Vol 14 (14) ◽  
pp. 1881-1884 ◽  
Author(s):  
Toshiki Maetani ◽  
Nobuhiro Hakuba ◽  
Masafumi Taniguchi ◽  
Jun Hyodo ◽  
Yoshitaka Shimizu ◽  
...  
Keyword(s):  
Free Radical ◽  
Hair Cell ◽  
Cell Loss ◽  
Free Radical Scavenger ◽  
Radical Scavenger ◽  
Hair Cell Loss ◽  
Inner Hair Cell

scholarly journals A Complex of RIM2alpha and RIM-Binding Protein 2 Stabilizes Slow Voltage-Dependent Inactivation of Cochlear Inner Hair Cell Cav1.3 L-Type Ca2+ Channels

2018 ◽  
Vol 114 (3) ◽  
pp. 637a-638a
Author(s):  
Nadine J. Ortner ◽  
Alexandra Pinggera ◽  
Anita Siller ◽  
Nadja Hofer ◽  
Niels Brandt ◽  
...  
Keyword(s):  
Hair Cell ◽  
Binding Protein ◽  
Inner Hair Cell ◽  
Dependent Inactivation ◽  
Voltage Dependent ◽  
Ca2 Channels

scholarly journals Individual synaptic vesicles mediate stimulated exocytosis from cochlear inner hair cells

2018 ◽  
Vol 115 (50) ◽  
pp. 12811-12816 ◽  
Author(s):  
Chad Paul Grabner ◽  
Tobias Moser
Keyword(s):  
Hair Cells ◽  
Synaptic Vesicles ◽  
Basolateral Membrane ◽  
Mean Amplitude ◽  
Auditory Pathway ◽  
Inner Hair Cell ◽  
Excitatory Postsynaptic Currents ◽  
High Level ◽  
High Degree ◽  
Channel Type

Spontaneous excitatory postsynaptic currents (sEPSCs) measured from the first synapse in the mammalian auditory pathway reach a large mean amplitude with a high level of variance (CV between 0.3 and 1). This has led some to propose that each inner hair cell (IHC) ribbon-type active zone (AZ), on average, releases ∼6 synaptic vesicles (SVs) per sEPSC in a coordinated manner. If true, then the predicted change in membrane capacitance (Cm) for such multivesicular fusion events would equate to ∼300 attofarads (aF). Here, we performed cell-attached Cm measurements to directly examine the size of fusion events at the basolateral membrane of IHCs where the AZs are located. The frequency of events depended on the membrane potential and the expression of Cav1.3, the principal Ca2+-channel type of IHCs. Fusion events averaged 40 aF, which equates to a normal-sized SV with an estimated diameter of 37 nm. The calculated SV volumes showed a high degree of variance (CV > 0.6). These results indicate that SVs fused individually with the plasma membrane during spontaneous and evoked release and SV volume may contribute more variability in EPSC amplitude than previously assumed.

scholarly journals THE ULTRASTRUCTURE OF THE SENSORY HAIRS AND ASSOCIATED ORGANELLES OF THE COCHLEAR INNER HAIR CELL, WITH REFERENCE TO DIRECTIONAL SENSITIVITY

1966 ◽  
Vol 29 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Arndt J. Duvall ◽  
Åke Flock ◽  
Jan Wersäll
Keyword(s):  
Guinea Pig ◽  
Hair Cell ◽  
Basal Body ◽  
Organ Of Corti ◽  
Sensory Cells ◽  
Directional Sensitivity ◽  
Inner Hair Cell ◽  
Lateral Line Organ ◽  
Sensory Hairs ◽  
Line Organ

From the apical end of the inner hair cell of the organ of Corti in the guinea pig cochlea protrude four to five rows of stereocilia shaped in a pattern not unlike the wings of a bird. In the area devoid of cuticular substance facing toward the tunnel of Corti lies a consistently present centriole. The ultrastructure of this centriole is similar to that of the basal body of the kinocilium located in the periphery of the sensory hair bundles in the vestibular and lateral line organ sensory cells and to that of the centrioles of other cells. The physiological implications of the anatomical orientation of this centriole are discussed in terms of directional sensitivity.

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