Cochlear Electroanatomy: Influence on Information Processing

The term electroanatomy was introduced by von Bekesy (1951) during his studies aimed at determining the resistance and capacitance patterns that corresponded to the structural features of the cochlea. Considerations of gross impedance configurations (studied by several groups in recent years: Kurokawa, 1965; Johnstone et al., 1966: Honrubia and Ward, 1969; Strelioff, 1973; Honrubia et al. 1976; Cannon, 1976; Geisler et al., 1977) may now be refined by incorporating individual hair cell characteristics. Recent intracellular recordings from mammalian hair cells (Russell and Sellick, 1978; Dallos et al., 1982) provide various electrical measures that describe the properties of these cells and highlight differences between inner (IHC) and outer hair cells (OHC). The purpose of this paper is to consider a simple circuit model of a cochlear cross-section and to investigate relationships between computed electrical quantities and those obtained experimentally. It is shown that several hitherto baffling differences between IHC and OHC electrical properties are a simple consequence of their impedance configurations. The results also suggest that electrical interactions between OHCs and IHCs are highly unlikely.