CHARACTERIZATION OF THE BRAIN-STEM AUDITORY-EVOKED POTENTIAL (BAEP) IN THE GREY SHORT-TAILED OPOSSUM (MONODELPHIS-DOMESTICA)

Brainstem auditory evoked potentials (BAEP) have been measured and cha racterized in the marsupial Monodelphis domestica in response to toneb urst stimulation. Five peaks are usually identified. The BAEP occurs w ithin a lime window of 5 ms starting 1.2 ms after onset of stimulation . Latencies decrease with increasing stimulus level at a rate of about -11 mu s/dB. At high stimulus frequencies latencies are shorter than with lower frequencies and shorten at a rate of about -0.2 ms/octave, The wave pattern changes in dependence on stimulus frequency and stimu lus level. An additional peak between peaks ii and iii occurs for freq uencies above 12 kHz at stimulus levels well above threshold.