[Properties of the derived cochlear action potential during tonal forward masking in guinea pigs]

In awake preimplanted guinea pigs, characteristics of auditory nerve and derived action potentials were investigated using a pure-tone forward masking paradigm. Auditory nerve action potentials are recorded from round window. The derived potential was obtained by subtracting the masked action potential from unmasked response. The results show that the derived potential is more sensitive to changes in auditory nerve action potential during masking than widely used indicator of masking--the decrement in auditory nerve action potential. Derived response reflects the response changes both in amplitude and waveform induced by masker. The differences between the auditory nerve and derived action potentials suggest that the amplitude and time changes in the derived potential give a more detailed information on the characteristics of the auditory nerve fibers responses.