The optokinetic head nystagmogram of the frog

An electronic device for recording optokinetic head nystagmus is described. By feeding a point-like mass (radiator) with an alternating current generator, alternating voltage can be measured on a large flat plate (receptor), which depends on the distance of the radiator from the receptor. The radiator was fixed on the head of the frog, and could move between a pair of receptors. Voltage changes during head motions can be recorded in the form of nystagmogram. The head nystagmogram of the frog proved to be similar to that of mammals. Rotation of the optokinetic drum to one direction for several minutes resulted in habituation (decrease of frequency or stopping of head motions). Based on the frequency and amplitude pattern several types of optokinetic head nystagmus could be identified.