Compound action potentials recorded intracranially from the auditory nerve in man

We describe the characteristics of the compound action potentials recorded from the intracranial part of the auditory nerve in man and the ralation between this potential and the various peaks in the auditory brain stem evoked potential. Recorded using a monopolar electrode, the shape of this potential varies from subject to subject. It often has a triphasic shape as can be expected of the field potentials of a long nerve. The main negative peak occurs 3.0 to 3.8 ms after the onset of a 2000-Hz stimulus tone at 90 dB. Recordings from two sites on the nerve have a similar wave shape. The difference in the latencies of these two recordings is associated with the estimated conduction velocity of the nerve. The latency of the main negative peak in the compound action potential of the auditory nerve was found to match the latency of the second mastoid-positive (vertex-negative) peak of the brain stem evoked potentials recorded from the scalp.