Automated determinination of head gaze in rodents

Behavioral experiments to determine the sensory performance of mice or rats often require the measurement of the animal´s head gaze. Nevertheless, commercial systems for video tracking of laboratory animals are often restricted to tracking of the body position and sometimes the nose position, leading to defective estimates of the gaze direction or require several artificial markers. Most experimenters rely on subjective judgments of this important experimental measurement. In this study we present three algorithms to determine the exact gaze of freely moving rodents. Two of these algorithms rely on artificial markers which are attached to the animal´s head. One approach uses knowledge about the body shape of rodents to track gaze without the use of artificial markers. All three algorithms determine the direction of gaze more precisely than a human observer and avoid systematic errors occurring in previously available tracking algorithms.