Biomaterial Database

Temporal properties of the red-green chromatic mechanism. 1994

R T Eskew, and C F Stromeyer, and R E Kronauer

Division of Applied Sciences, Harvard University, Cambridge, MA 02138.

The temporal properties of the red-green chromatic mechanism were studied with red and green equiluminant flashes of 1 deg diameter presented in the center of a bright (800-3000 td) yellow adapting field. A subthreshold 200 msec red or green flash makes an immediately subsequent, suprathreshold yellow luminance flash appear tinged with the complementary color. The chromatic flash also makes a subsequent chromatic flash of the same hue harder to detect and identify, and makes a flash of the opposite hue easier to detect and identify. These results indicate that the response of the red-green mechanism changes polarity during its time-course, suggesting that the chromatic temporal impulse-response function has a negative lobe. Pairs of chromatic pulses were used to estimate the shape of the chromatic impulse-response. The estimated impulse-response function has a zero crossing near 90 msec, followed by a long, shallow negative lobe. We also measured threshold-duration functions; the critical duration for the chromatic and luminance flashes is about 95 and 45 msec, respectively. Chromatic sensitivity (measured in cone contrast units) is 10 times greater than luminance sensitivity for long durations, and is 3 times greater for all durations less than 45 msec.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D003118	Color Perception	Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.	Color Perceptions,Perception, Color,Perceptions, Color
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000221	Adaptation, Ocular	The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)	Light Adaptation,Adaptation, Light,Adaptations, Light,Adaptations, Ocular,Light Adaptations,Ocular Adaptation,Ocular Adaptations
D012684	Sensory Thresholds	The minimum amount of stimulus energy necessary to elicit a sensory response.	Sensory Threshold,Threshold, Sensory,Thresholds, Sensory
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D015350	Contrast Sensitivity	The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate VISUAL ACUITY and to detect eye disease.	Visual Contrast Sensitivity,Sensitivity, Contrast,Sensitivity, Visual Contrast