[Brain stem auditory evoked responses in rats. Effects of the development, stimulation rate and electrode placement]

Brainstem auditory evoked responses (BAER) were studied in Long-Evans rats in relation to development, stimulation frequency and electrode placement. Recordings made on day 11 of life showed no BAER. From day 14 on, four BAER waves were observed and centripetal maturational changes in wave latency were evident. Wave I attained adult latency values at day 20-22, wave II at day 24-25, wave II at day 24-25, and wave IV at day 39 of life. BAER latencies elicited by 8,000-Hertz tone-pips were shorter than those obtained with clicks and 4,000 Hz. Only wave II latency measures were affected significantly by electrode location.