Modulation of Voltage Responses to 100 Hz Tones by High Frequency Tones in Cochlear Hair Cells
Inner (IHC) and outer (OHC) hair cells have been ascribed separate roles in mechanosensory transduction in the cochlea. The role of IHCs is assumed to be largely passive in that IHCs respond to the shear displacement between the tectorial membrane and the reticular lamina. The OHCs, on the other hand, may have an interactive role which, through electromechanical feedback of energy to the cochlear partition, enables them to control the shear displacements imparted to the mcs. The relative gain and phase at which the OHCs feed back energy and the relative mechanical impedance of the major elements (the tectorial and basilar membranes) of the cochlear partition, are crucial to the effectiveness of the feedback process in bringing about the sharp tuning which has been observed in the mechanical properties of the cochlear partition (Sellick et aI., 1982) and in the response of hair cells (Russell and Sellick, 1978; Dallos et al., 1982) and auditory fibres. (e.g. Kiang et al., 1965). As a means of exploring some of the properties of the interactive electromechanical processes in the cochlea, we have made intra- and extracellular recordings from IRCs and OHCs in the basal, high frequency turn of the guinea-pig cochlea and measured the voltage responses to a combination of a low frequency (100 Hz) tone and a high frequency tone at frequencies within a bandwith of approximately half an octave above and one octave below the characteristic frequency (CF) of the hair cells.
KeywordsHair Cell Characteristic Frequency Outer Hair Cell Shear Displacement Basilar Membrane
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