Contributing generator of frequency-following response in man.

A contributing generator of the frequency-following response (FFR) was identified in a patient with severe neurological impairment, by comparing latencies and phase shifts of the FFR to the latency of the auditory brainstem evoked responses (ABR), and by comparing the duration of the FFR to that of the acoustic stimulus. In this patient, the ABR comprised only waves I and II; activity in the inferior colliculus was not identified. Both onset and offset latencies and phase shifts of the FFR were substantially shorter than the latency of the first wave of the ABR. The duration of the FFR corresponded precisely to that of the acoustic stimulus. These results are interpreted as supporting the view that the cochlear microphonic potential (CM) contributes to the scalp-recorded FFR.