A Study of Electrical Middle Latency Response in a Cat: Effect of Stimulation Rate and Pulse Duration

Ahn, Soo Yong; Park, Ji Sang; Bae, Woo Yong; Kim, Lee Suk; Jeong, Sung Wook

Abstract

BACKGROUND AND OBJECTIVES: Electrically evoked middle latency response (EMLR) has several advantages over electrically evoked auditory brainstem response (EABR). The major component peaks of EMLR lie outside the region of stimulus artifacts and it reflects the activation of a more significant portion of the auditory pathway than EABR. It is known that several conditions alter the general morphology, amplitude, and latency of the waveforms of EMLR. The purpose of this study was to record and evaluate the effects of stimulation rate and pulse duration on detectability, latency and amplitude of EMLR in the cat. MATERIALS AND METHOD: EMLR was recorded in response to 9 experimental conditions-3 conditions of pulse duration (150, 200, 250 micron sec biphasic) at each of 3 conditions of stimulation rate (2, 6 and 10/sec)-after electrical stimulation at the round window in 7 cats.
RESULTS
PA was identified in all conditions. PB was obtained from 17 of the 63 waves. The latency of PA was significantly shorter and the amplitude of PA was significantly larger for the stimulation rate of 10/sec and the pulse duraion of 250 micron sec compared with other conditions.
CONCLUSION
We found that based on the present data, the optimal stimultion condition for EMLR in our laboratory was the stimulation rate of 10/sec and the pulse duration of 250 micron sec. This data can provide a basis for the appropriate stimulation condition of EMLR in human.