Responses from Single Auditory Units in the Eighth Nerve of the Leopard Frog

Auditory units in the eighth nerve of the leopard frog (Rana pipiens) are frequency selective with best frequencies from less than 100 Hz to near 2000 Hz. There are two distinct types of units, simple and complex. Simple units are most sensitive to high-frequency tones, are usually spontaneous, and cannot be inhibited by sound. Complex units usually have best frequencies below 700 Hz and each can be inhibited by tones with frequencies above its best frequency. The primary auditory units of the leopard frog are similar to those found in the bullfrog and the green frog. A preliminary study of the spectral characteristics of R. pipiens mating calls indicates that both types of units would be excited by these sounds. This suggests that mating-call detection in the leopard frog may depend upon the excitation of simple and complex units, as it does in the bullfrog.