Electrophysiological evidence for the existence of orientation and size detectors in the human visual system
F. W. Campbell,L. Maffei +1 more
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TLDR
The evoked potential in response to a grating alternating in phase at 8 c/s was recorded as a function of contrast from the occiput of man.Abstract:
1 The evoked potential in response to a grating alternating in phase at 8 c/s was recorded as a function of contrast from the occiput of man
2 It was found that a linear relation exists between the log of contrast and the amplitude of the evoked potential
3 Extrapolation to zero amplitude voltage of the regression line between the amplitude of the evoked potential and log contrast predicts the psychophysical threshold This law was found to hold over the wide range of spatial frequencies tested
4 Below 3 c/deg the results are best fitted with two regression lines; one of these is generated from the foveal and the other from the parafoveal representation in the cortex
5 The slope of the regression lines was found to be almost independent of either the spatial frequency or the area of the stimulus grating
6 The slope of the regression lines could be markedly increased by using as a stimulus either two different spatial frequencies, or two different orientations, presented simultaneously
7 Using the evoked potential the selectivity to orientation was found to be so high that a channel was not influenced by another orientation 15° away
8 The channels selectively sensitive to spatial frequency were highly selective and were not influenced by another spatial frequency one octave removed in spatial frequency
9 It is concluded that in man there exist neurones highly selective to both orientation and spatial frequencyread more
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Physiological and anatomical evidence for a magnocellular defect in developmental dyslexia
TL;DR: This paper found that dyslexic subjects showed diminished visual evoked potentials to rapid, low-contrast stimuli but normal responses to slow or high contrast stimuli, consistent with a defect in the magnocellular pathway at the level of visual area 1 or earlier.
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Perception and discrimination as a function of stimulus orientation: The "oblique effect" in man and animals.
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The steady-state visual evoked potential in vision research: A review.
Anthony M. Norcia,L. Gregory Appelbaum,Justin M. Ales,Benoit R. Cottereau,Benoit R. Cottereau,Bruno Rossion +5 more
TL;DR: The purpose of this article is to describe the fundamental stimulation paradigms for steady-state visual evoked potentials and to illustrate these principles through research findings across a range of applications in vision science.
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The orientation and direction selectivity of cells in macaque visual cortex
TL;DR: There is a bimodal distribution of direction-specific and nondirection-specific cells, with similar orientation tuning in each class, and three simple receptive field models are shown to differ in their abilities to account for results.
References
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Journal ArticleDOI
Optical and retinal factors affecting visual resolution.
F. W. Campbell,D G Green +1 more
TL;DR: An improved version of the well-known interference fringe technique which theoretically allows a sinusoidal pattern of very high contrast to be formed directly on the retina to be obtained without prior modification by the optics of the eye is reported.
Journal ArticleDOI
The representation of the visual field on the cerebral cortex in monkeys.
P. M. Daniel,D. Whitteridge +1 more
TL;DR: On the basis of his extensive and elegant anatomical investigations on the visual cortex, Poliak (1932) suggested that a mathematical projection of the retina on the cerebral cortex must exist and this work has made such a surface, folded it and compared it with the calcarine cortex of the monkey.
Journal ArticleDOI
Spatial and Temporal Contrast-Sensitivity Functions of the Visual System
TL;DR: In this paper, the reciprocal nature of these spatio-temporal interactions can be particularly clearly expressed if the threshold contrast is determined for a grating target whose luminance perpendicular to the bars is given by where m is the contrast, v the spatial frequency, and ƒ the temporal frequency of the target.
Journal ArticleDOI
The effect of orientation on the visual resolution of gratings
TL;DR: Experiments were designed to evaluate the optical and neurophysiological factors involved in visual resolving power for objects oriented obliquely as compared with horizontal and vertical orientations.
Journal ArticleDOI
Monocular versus Binocular Visual Acuity
F. W. Campbell,D G Green +1 more
TL;DR: The technique of Schade1 is modified so that a grating target is generated on an oscilloscope by supplying suitable signals to the x, y and z axes, and it could be continuously varied both in contrast and fineness without the mean luminance of the screen changing.
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