Click evoked eighth nerve and brain stem responses (electrocochleogram)--experimental observations in the cat.

The origin of waves two to five occurring in the first 10 milliseconds after repetitive click stimuli is not definitely established. Published studies have suggested that waves two and three are derived from the cochlear nucleus and superior olivary complex respectively and that waves four and five are generated by the inferior colliculus. Our studies of the effect of chronic brain stem lesions in the cat do not support this hypothesis of specific localization, but reveal that a more general reduction in amplitude, and at times prolongation in latency, occurs with lesions in the pons and lower midbrain and that wave one amplitude is also diminished with brain stem lesions.