title: Depth perception from moving cast shadow in macaque monkey.
abstract: In the present study, we investigate whether the macaque monkey can perceive motion in depth using a moving cast shadow. To accomplish this, we conducted two experiments. In the first experiment, an adult Japanese monkey was trained in a motion discrimination task in depth by binocular disparity. A square was presented on the display so that it appeared with a binocular disparity of 0.12 degrees (initial position), and moved toward (approaching) or away from (receding) the monkey for 1s. The monkey was trained to discriminate the approaching and receding motion of the square by GO/delayed GO-type responses. The monkey showed a significantly high accuracy rate in the task, and the performance was maintained when the position, color, and shape of the moving object were changed. In the next experiment, the change in the disparity was gradually decreased in the motion discrimination task. The results showed that the performance of the monkey declined as the distance of the approaching and receding motion of the square decreased from the initial position. However, when a moving cast shadow was added to the stimulus, the monkey responded to the motion in depth induced by the cast shadow in the same way as by binocular disparity; the reward was delivered randomly or given in all trials to prevent the learning of the 2D motion of the shadow in the frontal plane. These results suggest that the macaque monkey can perceive motion in depth using a moving cast shadow as well as using binocular disparity.
authors.affiliation: Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Department of Cognitive Neurobiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Saneyuki
authors.initials: S
authors.lastname: Mizutani
authors.affiliation: Department of Cognitive Neurobiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Usui
authors.affiliation: Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Yokota
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Mizusawa
authors.affiliation: Department of Cognitive Neurobiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Taira
authors.affiliation: Department of Cognitive Neurobiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: katz.cnb@tmd.ac.jp.
authors.forename: Narumi
authors.initials: N
authors.lastname: Katsuyama
mesh_terms: D000818:Animals; D003867:Depth Perception; D004192:Discrimination, Psychological; D005260:Female; D007088:Illusions; D008251:Macaca; D009039:Motion Perception; D010775:Photic Stimulation / Q000379:methods; D015357:Vision Disparity
keywords: Cast shadow; Depth cue; Disparity; Macaque monkey; Motion in depth