![]() ![]() ( b) For each stimulus condition, depth-tuning curves are shown for an example MT neuron. Background dots near the receptive field (RF) were masked. The dynamic perspective condition is the same as the retinal motion condition except that a three-dimensional cloud of background dots was added to the display. In the retinal motion condition, the animal's head and eyes are stationary, but visual stimuli replicate the image motion experienced in the motion parallax condition. In the motion parallax condition, animals experience full-body translation and make counteractive eye movements to maintain fixation on a world-fixed target (yellow cross). ( a) Frontal views for each experimental condition. Stimulus conditions used in the dynamic perspective experiment of Kim et al. Thin curves represent average eye position and velocity traces for a single session, in equivalent stimulus units. Thick black and grey curves represent the head movement trajectory for two possible starting phases. Movement followed one cycle of a modified sinusoid in the frontoparallel plane, and animals were trained to maintain fixation on a world-fixed target. ( d) Animals were passively translated laterally using a motion platform. ![]() Three depths-far (+1°), near (−1°) and zero-are illustrated. ( c) Random-dot stimuli were scaled so that size and density were identical across simulated depths. Without pictorial depth cues, an extra-retinal signal is needed to determine depth-sign. ( b) The opposite occurs during leftward head movement. ( a) As the head moves to the right, the image of a near object moves leftward, while the image of a far object moves rightward. to establish neural correlates of depth from motion parallax. Schematic of motion parallax and stimulus design used by Nadler et al. We examine a potential neural substrate in the middle temporal visual area for depth perception based on motion parallax, and we explore the nature of the signals that provide critical inputs for disambiguating depth-sign.This article is part of the themed issue 'Vision in our three-dimensional world'.ĭepth motion parallax neural computation. We review recent advances in elucidating the neural mechanisms for representing depth-sign (near versus far) from motion parallax. Although perception of depth based on motion parallax has been studied extensively in humans, relatively little is known regarding the neural basis of this visual capability. When an observer translates relative to their visual environment, the relative motion of objects at different distances (motion parallax) provides a powerful cue to three-dimensional scene structure. In addition to depth cues afforded by binocular vision, the brain processes relative motion signals to perceive depth. ![]()
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