For example, the slow (differential pressure across the OCC) component showed no pressure notch

For example, the slow (differential pressure across the OCC) component showed no pressure notch. components of the active feedback are considered explicitlyorgan of Corti mechanics, and outer hair cell electro-mechanics. Physiological properties for the outer hair cells were incorporated, such as the active force gain, mechano-transduction properties, and membrane RC time constant. Instead of a kinematical model, a fully deformable 3D finite element model was used. We show that the organ of Corti mechanics dictate L 006235 the longitudinal trend of cochlear amplification. Specifically, our results suggest that two mechanical conditions are responsible for location-dependent cochlear amplification. First, the phase of the outer hair cells somatic force with respect to its elongation rate L 006235 varies along the cochlear length. Second, the local stiffness of the organ of Corti complex felt by individual outer hair cells varies L 006235 along the cochlear length. We describe how these two mechanical conditions result in greater amplification toward the base of the cochlea. Author summary The mammalian cochlea encodes sound pressure levels over six orders of magnitude. This wide dynamic range is definitely achieved by amplifying fragile seems. The outer hair cells, one of two types Rabbit polyclonal to EDARADD of receptor cells in the cochlea, are known as the cellular actuators that provide power for the amplification. It is well known that high rate of recurrence sounds encoded in the basal change of the cochlea are amplified more than low rate of recurrence sounds encoded in the apical change of the cochlea. This difference in amplification has been ascribed to a difference in electrophysiological properties, such as the membrane capacitance and conductance of the outer hair cells at different locations. Whether the outer hair cells have a sufficient range of electrophysiological properties to explain the location dependent amplification has long been a topic of scientific argument. In this study, we present an alternative explanation for how the low and high rate of recurrence sounds are amplified in a different way. Using a detailed computational model of the cochlear epithelium (the organ of Corti), we demonstrate the micro-mechanics of the organ of Corti can clarify the variance of amplification with longitudinal location in the cochlea. Intro The mammalian cochlea encodes sounds with pressure levels ranging over six orders of magnitude into neural signals. This wide dynamic range of the cochlea is definitely achieved by the amplification of low amplitude seems. The outer hair cells have been identified as the mechanical actuators that generate the causes needed for cochlear amplification [1]. Cochlear amplification is dependent on location along the cochlear size. For example, relating to measurements of the chinchilla cochlea, the L 006235 amplification element of basilar membrane (BM) vibrations was about 40 dB in basal locations while it was 15 dB in apical locations [2C4]. Theoretical studies possess reproduced location-dependent cochlear amplification by adopting tonotopic electrophysiological properties, such as the active feedback gain of the outer hair cells [5, 6], or the mechano-transduction properties of the outer hair cell stereocilia [7, 8]. These studies are based on experimental reports concerning the tonotopy of the outer hair cells electrophysiological properties [e.g., 9, 10C12]. On the other hand, recent experimental observations suggest that organ of Corti mechanics may play a role in cochlear amplification. For example, organ of Corti micro-structures vibrate either in phase or out of phase depending on activation level and rate of recurrence [13C16]. These observations challenge a long-standing platform for modeling the organ of Corti mechanicsrigid body kinematics, launched by ter Kuile [17]. A fully deformable organ of Corti may have implications for cochlear amplification. Micro-mechanical aspects of cochlear power amplification were investigated in our earlier study, using a computational model of the cochlea [18]. The model features detailed organ of Corti mechanics analyzed using a 3-D finite element method, and up-to-date outer hair cell physiology. In that earlier work [18], it was shown the stiffness of the organ of Corti complex (OCC) felt.