scholarly journals Ventral pathway visual cortex: Representation by parts in a whole object reference frame

2012 ◽  
Vol 12 (9) ◽  
pp. 1382-1382
Author(s):  
C. E. Connor ◽  
A. Pasupathy ◽  
S. L. Brincat ◽  
Y. Yamane ◽  
C.-C. Hung
Keyword(s):  
Visual Cortex ◽  
Reference Frame ◽  
Ventral Pathway ◽  
Object Reference

Shape representation in ventral pathway visual cortex

2004 ◽  
Vol 1269 ◽  
pp. 23-25
Author(s):  
Charles E. Connor ◽  
Anitha Pasupathy
Keyword(s):  
Visual Cortex ◽  
Shape Representation ◽  
Ventral Pathway

A New Approach of Generating Object Reference Frame for Maxillary Dental Arch

2016 ◽  
Vol 74 (9) ◽  
pp. e26-e27
Author(s):  
D.C. Ho ◽  
J. Li ◽  
C.M. Chang ◽  
P. Yuan ◽  
J. Teichgraeber ◽  
...  
Keyword(s):  
Reference Frame ◽  
Dental Arch ◽  
New Approach ◽  
Object Reference

scholarly journals Short-term plasticity of the human adult visual cortex measured with 7T BOLD

2018 ◽  
Author(s):  
Paola Binda ◽  
Jan W. Kurzawski ◽  
Claudia Lunghi ◽  
Laura Biagi ◽  
Michela Tosetti ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Frequency Tuning ◽  
Ocular Dominance ◽  
Monocular Deprivation ◽  
Homeostatic Plasticity ◽  
Short Term ◽  
Parvocellular Pathway ◽  
Human Adult ◽  
Spatial Frequencies ◽  
Ventral Pathway

AbstractVisual cortex, particularly V1, is considered to be resilient to plastic changes in adults. In particular, ocular dominance is assumed to be hard-wired after the end of the critical period. We show that short-term (2h) monocular deprivation in adult humans boosts the BOLD response to the deprived eye, changing ocular dominance of V1 vertices, consistently with homeostatic plasticity. The boost is strongest in V1, present in V2, V3 & V4 but absent in V3a and MT. Assessment of spatial frequency tuning in V1 by a population Receptive-Field technique shows that deprivation primarily boosts high spatial frequencies, consistent with a primary involvement of the parvocellular pathway. Crucially, the V1 deprivation effect correlates across participants with the perceptual increase of the deprived eye dominance assessed with binocular rivalry, suggesting a common origin. Our results demonstrate that visual cortex, particularly the ventral pathway, retains a high potential for homeostatic plasticity in the human adult.

scholarly journals Functional specialization in rat occipital and temporal visual cortex

2014 ◽  
Vol 112 (8) ◽  
pp. 1963-1983 ◽  
Author(s):  
Ben Vermaercke ◽  
Florian J. Gerich ◽  
Ellen Ytebrouck ◽  
Lutgarde Arckens ◽  
Hans P. Op de Beeck ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Functional Properties ◽  
Temporal Cortex ◽  
Direction Selectivity ◽  
The Other ◽  
Functional Specialization ◽  
Gradual Change ◽  
Visual Areas ◽  
Ventral Pathway ◽  
Awake Rats

Recent studies have revealed a surprising degree of functional specialization in rodent visual cortex. Anatomically, suggestions have been made about the existence of hierarchical pathways with similarities to the ventral and dorsal pathways in primates. Here we aimed to characterize some important functional properties in part of the supposed “ventral” pathway in rats. We investigated the functional properties along a progression of five visual areas in awake rats, from primary visual cortex (V1) over lateromedial (LM), latero-intermediate (LI), and laterolateral (LL) areas up to the newly found lateral occipito-temporal cortex (TO). Response latency increased >20 ms from areas V1/LM/LI to areas LL and TO. Orientation and direction selectivity for the used grating patterns increased gradually from V1 to TO. Overall responsiveness and selectivity to shape stimuli decreased from V1 to TO and was increasingly dependent upon shape motion. Neural similarity for shapes could be accounted for by a simple computational model in V1, but not in the other areas. Across areas, we find a gradual change in which stimulus pairs are most discriminable. Finally, tolerance to position changes increased toward TO. These findings provide unique information about possible commonalities and differences between rodents and primates in hierarchical cortical processing.

scholarly journals Representation of Gravity-Aligned Scene Structure in Ventral Pathway Visual Cortex

2016 ◽  
Vol 26 (6) ◽  
pp. 766-774 ◽  
Author(s):  
Siavash Vaziri ◽  
Charles E. Connor
Keyword(s):  
Visual Cortex ◽  
Scene Structure ◽  
Ventral Pathway

scholarly journals Visual Awareness Is Limited by the Representational Architecture of the Visual System

2015 ◽  
Vol 27 (11) ◽  
pp. 2240-2252 ◽  
Author(s):  
Michael A. Cohen ◽  
Ken Nakayama ◽  
Talia Konkle ◽  
Mirta Stantić ◽  
George A. Alvarez
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Visual Masking ◽  
Visual Awareness ◽  
Neural Responses ◽  
Dorsal Pathway ◽  
Visual Hierarchy ◽  
Early Visual Cortex ◽  
Ventral Pathway ◽  
Brain Behavior

Visual perception and awareness have strict limitations. We suggest that one source of these limitations is the representational architecture of the visual system. Under this view, the extent to which items activate the same neural channels constrains the amount of information that can be processed by the visual system and ultimately reach awareness. Here, we measured how well stimuli from different categories (e.g., faces and cars) blocked one another from reaching awareness using two distinct paradigms that render stimuli invisible: visual masking and continuous flash suppression. Next, we used fMRI to measure the similarity of the neural responses elicited by these categories across the entire visual hierarchy. Overall, we found strong brain–behavior correlations within the ventral pathway, weaker correlations in the dorsal pathway, and no correlations in early visual cortex (V1–V3). These results suggest that the organization of higher level visual cortex constrains visual awareness and the overall processing capacity of visual cognition.

Practical Realization of a Reference System for Earth Dynamics by Satellite Methods

1975 ◽  
Vol 26 ◽  
pp. 341-380 ◽  
Author(s):  
R. J. Anderle ◽  
M. C. Tanenbaum
Keyword(s):  
Reference Frame ◽  
Polar Motion ◽  
Pole Position ◽  
Control Points ◽  
Significant Information ◽  
Crustal Motion ◽  
Average Reference ◽  
Future Data ◽  
Existing Data

AbstractObservations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.

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