scholarly journals Exploring the role of curvature for neural shape representations across hV4 and Lateral Occipital visual field maps

2017 ◽  
Vol 17 (10) ◽  
pp. 292
Author(s):  
Richard Vernon ◽  
Andre Gouws ◽  
Samuel Lawrence ◽  
Bruce Keefe ◽  
Declan McKeefry ◽  
...  
Keyword(s):  
Visual Field ◽  
Shape Representations ◽  
Visual Field Maps

The Psychologist-Educator Views the Relationship of Vision to Reading and Related Learning Disabilities

1981 ◽  
Vol 14 (10) ◽  
pp. 565-567 ◽  
Author(s):  
Jules C. Abrams
Keyword(s):  
Learning Disabilities ◽  
Visual Field ◽  
Visual Perception ◽  
Learning Disability ◽  
Visual Defects ◽  
Considerable Controversy ◽  
Visual Problems ◽  
Relationship Of ◽  
The Relationship

The role of visual problems in learning disability has been a source of considerable controversy for many years. One major issue in the continuing argument is the frequent confusion of labels and concepts in the visual field. It is important to view vision as a psychophysiologic mechanism and to differentiate it from a mechanistic orientation emphasizing the eyes. Most visual problems related to learning disability represent a breakdown in the ability of the eyes to function in an harmonious fashion, that is, some interference in binocular function. While visual defects should not be confused with defects in visual perception, the identification and treatment of visual problems is an important element in the diagnosis and remediation of learning disabilities.

scholarly journals Visual field map clusters in human cortex

2005 ◽  
Vol 360 (1456) ◽  
pp. 693-707 ◽  
Author(s):  
Brian A Wandell ◽  
Alyssa A Brewer ◽  
Robert F Dougherty
Keyword(s):  
Visual Field ◽  
Functional Mri ◽  
Spatial Organization ◽  
Perceptual Processing ◽  
Large Set ◽  
Human Cortex ◽  
General Properties ◽  
Visual Field Maps

We describe the location and general properties of nine human visual field maps. The cortical location of each map, as well as many examples of the eccentricity and angular representations within these maps, are shown in a series of images that summarize a large set of functional MRI data. The organization and properties of these maps are compared and contrasted with descriptions by other investigators. We hypothesize that the human visual field maps are arranged in several clusters, each comprising a group of maps that share a common foveal representation and semicircular eccentricity map. The spatial organization of these clusters suggests that the perceptual processing within each cluster serves related functions.

Stereopsis and the random element in the organization of the striate cortex

1979 ◽  
Vol 204 (1157) ◽  
pp. 415-434 ◽  
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Striate Cortex ◽  
Preferred Orientation ◽  
Field Orientation ◽  
Depth Discrimination ◽  
Striate Neurons ◽  
Random Scatter ◽  
Field Position

Receptive field position and orientation disparities are both properties of binocularly discharged striate neurons. Receptive field position disparities have been used as a key element in the neural theory for binocular depth discrimination. Since most striate cells in the cat are binocular, these position disparities require that cells immediately adjacent to one another in the cortex should show a random scatter in their monocular receptive field positions. Superimposed on the progressive topographical representation of the visual field on the striate cortex there is experimental evidence for a localized monocular receptive field position scatter. The suggestion is examined that the binocular position disparities are built up out of the two monocular position scatters. An examination of receptive field orientation disparities and their relation to the random variation in the monocular preferred orientations of immediately adjacent striate neurons also leads to the conclusion that binocular orientation disparities are a consequence of the two monocular scatters. As for receptive field position, the local scatter in preferred orientation is superimposed on a progressive representation of orientation over larger areas of the cortex. The representation in the striate cortex of visual field position and of stimulus orientation is examined in relation to the correlation between the disparities in receptive field position and preferred orientation. The role of orientation disparities in binocular vision is reviewed.

scholarly journals An Eye Movement Study on the Role of the Visual Field Defect in Pure Alexia

PLoS ONE ◽  
2014 ◽  
Vol 9 (7) ◽  
pp. e100898 ◽  
Author(s):  
Tobias Bormann ◽  
Sascha A. Wolfer ◽  
Wibke Hachmann ◽  
Wolf A. Lagrèze ◽  
Lars Konieczny
Keyword(s):  
Visual Field ◽  
Eye Movement ◽  
Visual Field Defect ◽  
Pure Alexia ◽  
Movement Study ◽  
Field Defect

The Role of Constant Curvature in 2-D Contour Shape Representations

Perception ◽  
10.1068/p6970 ◽  
2011 ◽  
Vol 40 (11) ◽  
pp. 1290-1308 ◽  
Author(s):  
Patrick Garrigan ◽  
Philip J Kellman
Keyword(s):  
Retention Interval ◽  
Constant Curvature ◽  
Visual Information ◽  
Recognition Performance ◽  
Shape Representations ◽  
Contour Shape ◽  
Position And Orientation ◽  
Retention Intervals ◽  
Invariant Shape

In early cortex, visual information is encoded by retinotopic orientation-selective units. Higher-level representations of abstract properties, such as shape, require encodings that are invariant to changes in size, position, and orientation. Within the domain of open, 2-D contours, we consider how an economical representation that supports viewpoint-invariant shape comparisons can be derived from early encodings. We explore the idea that 2-D contour shapes are encoded as joined segments of constant curvature. We report three experiments in which participants compared sequentially presented 2-D contour shapes comprised of constant curvature (CC) or non-constant curvature (NCC) segments. We show that, when shapes are compared across viewpoint or for a retention interval of 1000 ms, performance is better for CC shapes. Similar recognition performance is observed for both shape types, however, if they are compared at the same viewpoint and the retention interval is reduced to 500 ms. These findings are consistent with a symbolic encoding of 2-D contour shapes into CC parts when the retention intervals over which shapes must be stored exceed the duration of initial, transient, visual representations.

scholarly journals Rivalry Onset in and around the Fovea: The Role of Visual Field Location and Eye Dominance on Perceptual Dominance Bias

Vision ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 51
Author(s):  
Jody Stanley ◽  
Jason D. Forte ◽  
Olivia Carter
Keyword(s):  
Visual Field ◽  
Binocular Rivalry ◽  
Visual Space ◽  
Peripheral Visual Field ◽  
Eye Dominance ◽  
Initial Onset ◽  
Onset Period ◽  
Trained Observers ◽  
Field Location

When dissimilar images are presented to each eye, the images will alternate every few seconds in a phenomenon known as binocular rivalry. Recent research has found evidence of a bias towards one image at the initial ‘onset’ period of rivalry that varies across the peripheral visual field. To determine the role that visual field location plays in and around the fovea at onset, trained observers were presented small orthogonal achromatic grating patches at various locations across the central 3° of visual space for 1-s and 60-s intervals. Results reveal stronger bias at onset than during continuous rivalry, and evidence of temporal hemifield dominance across observers, however, the nature of the hemifield effects differed between individuals and interacted with overall eye dominance. Despite using small grating patches, a high proportion of mixed percept was still reported, with more mixed percept at onset along the vertical midline, in general, and in increasing proportions with eccentricity in the lateral hemifields. Results show that even within the foveal range, onset rivalry bias varies across visual space, and differs in degree and sensitivity to biases in average dominance over continuous viewing.

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