Studies of Motion Vision

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

De Valois/ De Valois (0111059) Studies of Motion Vision Lay Abstract This project is designed to increase our understanding of how the brain analyzes visual motion. Telling the difference visually between stationary and moving objects is a very difficult problem. The physiological responses of neurons in the visual system of macaque monkeys to stationary and moving objects will be examined and compared to the behavioral responses of human observers in similar tasks. Two major subtopics will be considered. An early step in the analysis of visual motion is the creation in the first visual cortical area (V1) of directionally-selective neurons, neurons that respond only if an object moves in a particular direction within the limited visual region from which the cell receives inputs. One topic of investigation will be how these cells are created; in particular, where do their inputs come from and how are they combined to produce directional selectivity. A specific model will be tested by several experiments on both directional V1 cells and on the cells in the lateral geniculate nucleus (LGN) that provide inputs to the directional cells. The results of these experiments will be compared to the results from related psychophysical studies on human observers. A second topic will be the way the color-vision system provides input to or interacts with the visual motion system. Psychophysical experiments on human observers will examine the effects of color alternation on the discrimination of the direction of motion of a luminance-varying grating. Different chromatic combinations will be used, including those that preferentially excite specific classes of photoreceptors or neurons in the LGN. Earlier work predicts differential effects for different color combinations. Physiological studies will examine the effects of color alternation on the responses of directionally-selective neurons in V1 for comparison to behavioral responses from humans. These studies will significantly advance our understanding of the initial mechanisms of the visual motion system in humans and other primates. In addition to increasing our knowledge of the brain and its organization, this work will contribute to the advancement of health and human understanding. The fuller understanding gained from these studies may also have direct application in the design of lighting systems, particularly for moving vehicles, and in other situations in which human factors concerns are significant. This project will contribute to the scientific education and training of both undergraduate and graduate students. Graduate students will be involved in the design, performance, analysis and publication of these studies. Undergraduate students will work as laboratory technicians and psychophysical subjects. When possible, they will also be involved in the design, performance, analysis and publication of the studies. Many former graduate students who have worked on similar projects in these laboratories have built distinguished careers in the study of vision. Several former undergraduates who have worked in these laboratories have become health workers or scientists. Students employed on similar projects in the past have come from both genders and many ethnic groups. This research, like previous work in these laboratories, is expected to increase the opportunities for students from minority groups to participate in scientific research and prepare for future careers of their own.