Acoustical Determinants of Audiogenic Seizures in Laboratory Mice

Abstract

Albino mice were tested for susceptibility to audiogenic seizures in sound fields of various frequencies and intensities. An attempt to fix the ears of the mice with respect to the sound source by suspending the mice with a large spring clip which grasped the dorsal skin-fold proved fruitless, for too few seizures were induced at any intensity. The mice were therefore tested in a small wire mesh cage suspended in front of the sound-transducer, and the positions of their ears during the treatment were recorded. At 10 kc, at least 92 db was needed to induce seizures in mice which had no previous seizures, while only 83 db were needed for animals which had previous seizures. The most effective frequencies for the induction of seizures were between 12 and 25 kc. Below 10 kc, the effectiveness dropped off sharply and was very low at 5 kc. Studies were not made above 25 kc. The peak of the mouse's audiogram is probably near the frequencies which are most effective for induction of seizures and is thus a little lower than that of the rat and about 1.5 octaves above that of man. The ability of mice to hear at frequencies which are ultrasonic for the human ear is probably the reason for the intense reactions of mice to complex sounds which seem of moderate intensity to man.