title: Compression, adaptation and efferent control in a revised outer hair cell functional model.
abstract: In the cochlea of the inner ear, outer hair cells (OHC) together with the local passive structures of the tectorial and basilar membranes comprise non-linear resonance circuits with the local and central (afferent-efferent) feedback. The characteristics of these circuits and their control possibilities depend on the mechanomotility of the OHC. The main element of our functional model of the OHC is the mechanomotility circuit with the general transfer characteristic y=ktanh(x-a). The parameter k of this characteristic reflects the axial stiffness of the OHC, and the parameter a working position of the hair bundle. The efferent synaptic signals act on the parameter k directly and on the parameter a indirectly through changes in the membrane potential. The dependences of the sensitivity and selectivity on changes in the parameters a and k are obtained by the computer simulation. Functioning of the model at low-level input signals is linear. Due to the non-linearity of the transfer characteristic of the mechanomotility circuit the high-level signals are compressed. For the adaptation and efferent control, however, the transfer characteristic with respect to the initial operating point should be asymmetrical (a>0). The asymmetry relies on the deflection of the hair bundle from the axis of the OHC.
authors.affiliation: Department of Applied Electronics, Kaunas University of Technology, LT-3031 Kaunas, Lithuania.
authors.forename: Antanas
authors.initials: A
authors.lastname: Stasiunas
authors.forename: Antanas
authors.initials: A
authors.lastname: Verikas
authors.forename: Marija
authors.initials: M
authors.lastname: Bacauskiene
authors.forename: Rimvydas
authors.initials: R
authors.lastname: Miliauskas
authors.forename: Natalija
authors.initials: N
authors.lastname: Stasiuniene
authors.forename: Kerstin
authors.initials: K
authors.lastname: Malmqvist
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D003051:Cochlea / Q000294:innervation / Q000502:physiology; D019245:Compressive Strength / Q000502:physiology; D004525:Efferent Pathways / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008954:Models, Biological; D009476:Neurons, Efferent / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods