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At least 163 records · Page 9Linked to original sources
PubMed2000

Molecular genetics of color vision and color vision defects.

Color is an extremely important component of the information that we gather with our eyes. Most of us use color so automatically that we fail to appreciate how important it is in our daily activities. It serves as a nonlinguistic code that gives us instant information about the world around us. From observing color, for example, we can find the bee sting on an infant's arm even before it begins to swell by looking for the little spot where the infant's skin is red. We know when fruit is ripe; the ripe banana is yellow not green. We know when meat is cooked because it is no longer red. When watching a football game, we can instantly keep track of the players on opposing teams from the colors of their uniforms. Using color, we know from a distance which car is ours in the parking lot--it is the blue one--and whether we will need to stop at the distant traffic light, even at night, when we cannot see the relative positions of red and green lights.

Color Perception↗
PubMed1980

Spatial characteristics of movement detection mechanisms in human vision. I. Achromatic vision.

Threshold illumination levels, It, for visual detection of white light targets, moving across spatially structured background fields, have been measured and it is shown that, for a given background illumination level, It depends upon the spatial characteristics of the background field structure. Thus, with the background composed of a square-waveform grating of fundamental spatial frequency f cycles/deg, It is maximum for an intermediate value of f, and falls as f increases or decreases from this value. The relationship between It and f characterizes the interaction between movement detection and the background grating, and is designated the IMG function. The parametric properties of the IMG functions are described and it is established that the mechanisms which give rise to these functions are sensitive to the movement, but not the spatial structure of the target. They correspond, therefore, to the movement-sensitive Y-type mechanisms, observed in electrophysiological studies of cat and primate visual pathways. The spatial distribution of sensitivity associated with the IMG functions has been computed by 2-D transform methods, the computation yielding circularly symmetric, centre-surround antagonistic "receptive field" distributions.

Adult↗
PubMed1995

Frontal lobe mechanisms subserving vision-for-action versus vision-for-perception.

In the typical course of daily events, we often gaze at an object, attend to its features and its place, reach toward it and grasp it, all with an awareness of what we are doing at the time. But behavior is not always thus. Gaze, attention, limb movement direction and awareness can be behaviorally dissociated from each other, and this review focuses on one such dissociation: that between the perception of an object and the use of that object's inherent spatial and nonspatial information for mediating visuomotor control. We review evidence that partially different neuronal systems underlie these two aspects of visual information processing. In neurophysiological studies of the primate frontal lobe, it has been possible to demonstrate that neural signals appearing to be visual responses reflect, at least in part, the motor significance of a stimulus. This finding has been confirmed, in separate studies, for both spatial and nonspatial visual information and supports the hypothesis that some frontal cortex activity reflects the selection and guidance of action rather than the properties of visual stimuli, per se. These findings are discussed in the context of neuropsychological studies indicating that accurate and appropriate movements are possible without perceptual awareness of the information guiding those movements.

Animals↗