Cochlear function reflected in mammalian hair cell responses.

This report describes response patterns recorded in inner and outer hair cells in the apical three turns of the guinea pig cochlea. Characteristic frequencies (CF) in these regions are approximately 270 Hz in turn four, 1000 Hz in turn three and 4000 Hz in turn two. Although the two receptor types exhibit differences in resting membrane potentials and in response phase at low stimulus frequencies, they both produce ac and dc receptor potentials in response to sound. When measured around CF, both cell types produce a depolarizing dc response at low and moderate levels. This contrasts with results published for basal-turn outer hair cells (Russell and Sellick, 1983; Cody and Russell, 1987) whose responses become asymmetrical only at very high levels.