Design of a miniature evoked potential testing system for animal assessment of hearing

A specially built apparatus has been designed to allow novel methodologies for simultaneous measurement of early, middle and late evoked potentials. Evoked potentials can be measured in active, unsedated, unrestrained rats. Typically, early evoked potentials are measured with animals that are anesthetized. Middle and late evoked potentials must be measured in awake animals. Chronically implanted electrodes provide the bioelectric potentials. To accomplish this active measurement, data are transferred wirelessly from a portable unit attached to the rat, to a computer via wireless Bluetooth. The system is controlled with a Raspberry Pi. Included are a differential input amplifier, A/D converter and low and high pass filters. The miniature system also includes a means to provide a wide range of auditory stimuli typically driving a small insert earphone. All programs and auditory stimuli are stored on micro SD cards. The pack stays in place and is not removable by the animal. This system is ideally suited for measurements of backward masking middle latency responses as a marker for Auditory Processing Disorders (APD). The pack is light and easily attachable.