Rate and frequency interactions in the auditory brainstem response of the adult rat.

Tone pip stimuli were used at different repetition rates to examine influences upon auditory brainstem response components. Rate increases to 80.1/s result in significant latency increases in waves IV and V at all test frequencies. Rate effects occur in rostral brainstem response components which show frequency related latencies different from wave I. Amplitude measures decline at higher repetition rates for waves I and IV at most test frequencies. Rate effects are most pronounced at 8 kHz stimulation which is around the optimal behavioral frequency in rat. At higher rates the second peak of wave I is enhanced at 8 kHz, whereas the third peak of wave I at 40 kHz disappears. These results demonstrate that tone-specific stimuli provide sensitive measures of latency, amplitude and wave morphology of components of the auditory brainstem response as a function of stimulus repetition.