Biomaterial Database

Interactions among spatial frequency and orientation channels adapted concurrently. 1988

M W Greenlee, and S Magnussen

Neurologische Universitätsklinik mit Abteilung für Neurophysiologie, Freiburg, F.R.G.

Interactions between size and orientation-specific mechanisms in the human visual system were investigated using a sequential adaptation technique. Subjects adapted to a vertical, 4 c/deg high-contrast (0.7) sinewave grating that was interleaved at a rate of 0.5 Hz with another adapting grating differing either in (1) spatial frequency or (2) orientation. Before and after adaptation contrast thresholds were measured for a vertical 4 c/deg sinewave test grating. The resultant elevation in contrast threshold was plotted as a function of the (1) spatial frequency or (2) orientation differences between the first and second adapting gratings. Maximum threshold elevation was found when both adapting gratings shared the same spatial frequency and orientation. Minimum elevations were found when the second grating's spatial frequency or orientation differed by approx. 1.5 octaves or 45 deg, respectively. Beyond these values threshold elevations reapproached the baseline value measured in a control condition, where the 4.0 c/deg adapting grating was interleaved with a blank. The minimum threshold elevations were 0.2-0.3 log units below the baseline level. The results suggest the existence of inhibitory interactions between neural mechanisms tuned to the size and orientation of retinal images.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009433	Neural Inhibition	The function of opposing or restraining the excitation of neurons or their target excitable cells.	Inhibition, Neural
D010364	Pattern Recognition, Visual	Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.	Recognition, Visual Pattern,Visual Pattern Recognition
D005556	Form Perception	The sensory discrimination of a pattern, shape, or outline.	Contour Perception,Contour Perceptions,Form Perceptions,Perception, Contour,Perception, Form,Perceptions, Contour,Perceptions, Form
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
D012399	Rotation	Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Clinorotation,Clinorotations,Rotations
D012684	Sensory Thresholds	The minimum amount of stimulus energy necessary to elicit a sensory response.	Sensory Threshold,Threshold, Sensory,Thresholds, Sensory
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