Relationships between trapezoidal EP variations and auditory nerve fiber responses in gerbils and guinea pigs

Abstract

It has been shown [Sokolich et al., J. Acoust. Soc. Am., 59, 963–974 (1976)] that most gerbil auditory nerve fibers show one of three time patterns of response to acoustically‐evoked trapezoidal time patterns of EP change. Pattern “A” is characteristic of fibers with CFs below 2 kHz, pattern “B”, of fibers with CFs between 3 and 6 kHz, and pattern “C”, of fibers with CFs above 8 kHz. Although all three patterns contain four distinct response components reflecting both static and dynamic aspects of trapezoidal EP change, the patterns differ in that the sign of one or more components depends on fiber CF. The present comparative study reveals that pattern “A” is exhibited by all guinea pig fibers with CFs below and by many fibers with CFs above 7 kHz. Nonetheless, some guinea pig fibers with CFs above 7 kHz show pattern “B”. In spite of the difference in the dependence of response pattern on CF, all patterns observed in both species support the conclusion that neither excitation nor inhibition of auditory nerve fibers is uniquely related to specific aspects of either static or dynamic changes in EP or to associated aspects of basilar membrane motion.