Cochlear potentials and auditory evoked potentials in the caiman (Caiman crocodilus (L.)).

Brain-stem auditory evoked potentials (BAEPs) and round window compound action potentials (CAPs) in response to rarefaction and condensation clicks were recorded from anaesthetized and artificially respired caiman. The recorded wave forms were substantially different from the brain-stem and round window potentials recorded in mammals, including man. In particular, wave latencies were much longer than in mammals. Wave amplitudes increased and latencies decreased significantly and reversibly with increases in stimulus intensity and body temperature. The latencies of the first positive wave (P1) in the BAEP and the first negative wave (N1) in the CAP are correlated and co-vary with stimulus level and body temperature. BAEP P1 thus represents the response of the auditory nerve. The cochlear microphonic (CM) latency in caiman is unaffected by stimulus intensity and by cooling of the animal.