ON THE MEASUREMENTS OF THE SPONTANEOUS MOTOR ACTIVITY OF SMALL LABO RATORY ANIMALS

Abstract

For the study of different aspects of spontaneous motor activity in mice and rats three kinds of activity cage have been devised.
The activity cage for recording the small movements has been designed upon the principle of condensor pick-up. The amplifier and ink-writing system of E.E.G. machine are utilized for this device. The instrument is capable of detesting small rapid as well as gross movements (e.g., respiratory, washing, grooming and running movements). and is also applicable for measuring the responsiveness of an animal to external stimuli.
The second, main activity cage is a revolving one with a counter modified from those described by Richter and Wang.
The third revolving cage is of the same size as the second, specially provided with a handle by which the experimenter can revolve the cage from outside. When a running mouse in the cage is about to repose, the experimenter gives instantly a bit of movement to the cage, then the mouse, provoked by the stimulus, resumes running continuously. The mean velocity of the free running without repose for five minutes is regarded as an index for the running ability (physical motor strength) of the animal.
Based on these measurements, some observations on spontaneous motor depression indued by chronic administration of methamphetamine or methylthiouracil are described.
During these experiments no physical constraint is imposed on and stressful situations for the animals are cautiously avoided.