Interaction between mechanical and electrical stimuli in hair cell systems

Abstract

In order to determine the effects of electrical potentials upon mechanically evoked responses of hair cell systems, the neural activity of single afferent fibers innervating the lateral line organ of the African clawed toad Xenopus laevis was recorded during stimulation with combinations of sinusoidal mechanical and electrical stimuli. It was found that a 2-Hz electrical stimulus modulated the amplitude of the response evoked by a 32-Hz mechanical stimulus by the same proportion that it modulates the spontaneous activity in the absence of mechanical stimuli. It was also found that responses to a 32-Hz electrical stimulus could be modulated by a 2-Hz mechanical stimulus. These results demonstrate that the gain of this hair cell system for one type of stimulus is determined by the instantaneous magnitude of the other stimulus. Similar interactions between mechanical stimuli and potentials generated by adjacent hair cells probably occur in other hair cell systems and may play an important role in signal processing. [Supported by grants from the Deafness Research Foundation and NINDS.]