An apparatus for the assessment of prepulse inhibition in the frog

A system for studying prepulse inhibition in the leopard frog is described herein. It entails a modification of an apparatus developed almost a century ago, by Yerkes, for his investigations of hearing in the frog. With the present system, a frog is restrained in a cylindrical vessel (constructed from a 35-mm film canister), and the canister is positioned in the apparatus so that the animal’s legs hang downward. A miniature solenoid is used to deliver a startle eliciting tap to the frog’s head, and the resulting leg movement is detected by an optical densitometer. In addition to providing a convenient way to restrain frogs, our system enabled us to, in part, replicate Yerkes’s basic procedures with these subjects. As did Yerkes, we found that an acoustic signal just prior to a tap on a frog’s head inhibits the leg movement that would otherwise be elicited.