Auditory collusion and a coupled couple of outer hair cells

The discrepancies between measured frequency responses of the basilar membr ane in the inner ear and the frequency tuning found in psychophysical exper iments led to Bekesy's idea of lateral inhibition in the auditory nervous s ystem(1). We now know that basilar membrane tuning can account for neural t uning(2), and that sharpening of the passive travelling wave depends on the mechanical activity of outer hair cells (OHCs)(3), but the mechanism by wh ich OHCs enhance tuning remains unclear. OHCs generate voltage-dependent le ngth changes at acoustic rates(4-8), which deform the cochlear partition(9- 11). Here we use an electrical correlate of OHC mechanical activity, the mo tility-related gating current, to investigate mechano-electrical interactio ns among adjacent OHCs. We show that the motility caused by voltage stimula tion of one cell in a group evokes gating currents in adjacent OHCs. The re sulting polarization in adjacent cells is opposite to that within the stimu lated cell, which may be indicative of lateral inhibition. Also such intera ctions promote distortion and suppression in the electrical and, consequent ly, the mechanical activity of OHCs. Lateral interactions may provide a bas is for enhanced frequency selectivity in the basilar membrane of mammals.