scholarly journals Local motion-contrast Interactions Influence Global Shape Perception

2013 ◽  
Vol 13 (9) ◽  
pp. 377-377
Author(s):  
G. Gurariy ◽  
G. Caplovitz
Keyword(s):  
Shape Perception ◽  
Local Motion ◽  
Global Shape ◽  
Motion Contrast

scholarly journals Allocation of attention to biological motion: Local motion dominates global shape

2011 ◽  
Vol 11 (3) ◽  
pp. 4-4 ◽  
Author(s):  
M. Hirai ◽  
D. R. Saunders ◽  
N. F. Troje
Keyword(s):  
Biological Motion ◽  
Local Motion ◽  
Global Shape

Center-Surround Interactions in the Middle Temporal Visual Area of the Owl Monkey

2000 ◽  
Vol 84 (5) ◽  
pp. 2658-2669 ◽  
Author(s):  
Richard T. Born
Keyword(s):  
Visual Motion ◽  
Receptive Fields ◽  
Visual Area ◽  
Motion Processing ◽  
Wide Field ◽  
Local Motion ◽  
Middle Temporal ◽  
Visual Motion Processing ◽  
Owl Monkey ◽  
Motion Contrast

Microelectrode recording and 2-deoxyglucose (2dg) labeling were used to investigate center-surround interactions in the middle temporal visual area (MT) of the owl monkey. These techniques revealed columnar groups of neurons whose receptive fields had opposite types of center-surround interaction with respect to moving visual stimuli. In one type of column, neurons responded well to objects such as a single bar or spot but poorly to large textured stimuli such as random dots. This was often due to the fact that the receptive fields had antagonistic surrounds: surround motion in the same direction as that preferred by the center suppressed responses, thus rendering these neurons unresponsive to wide-field motion. In the second set of complementary, interdigitated columns, neuronal receptive fields had reinforcing surrounds and responded optimally to wide-field motion. This functional organization could not be accounted for by systematic differences in binocular disparity. Within both column types, neurons whose receptive fields exhibited center-surround interactions were found less frequently in the input layers compared with the other layers. Additional tests were done on single units to examine the nature of the center-surround interactions. The direction tuning of the surround was broader than that of the center, and the preferred direction, with respect to that of the center, tended to be either in the same or opposite direction and only rarely in orthogonal directions. Surround motion at various velocities modulated the overall responsiveness to centrally placed moving stimuli, but it did not produce shifts in the peaks of the center's tuning curves for either direction or speed. In layers 3B and 5 of the local motion processing columns, a number of neurons responded only to local motion contrast but did so over a region of the visual field that was much larger than the optimal stimulus size. The central feature of this receptive field type was the generalization of surround antagonism over retinotopic space—a property similar to other “complex” receptive fields described previously. The columnar organization of different types of center-surround interactions may reflect the initial segregation of visual motion information into wide-field and local motion contrast systems that serve complementary functions in visual motion processing. Such segregation appears to occur at later stages of the macaque motion processing stream, in the medial superior temporal area (MST), and has also been described in invertebrate visual systems where it appears to be involved in the important function of distinguishing background motion from object motion.

scholarly journals Using classification images to reveal the critical features in global shape perception

2010 ◽  
Vol 10 (7) ◽  
pp. 1174-1174
Author(s):  
I. Kurki ◽  
A. Hyvarinen ◽  
J. Saarinen
Keyword(s):  
Shape Perception ◽  
Global Shape ◽  
Classification Images

scholarly journals Temporo-parietal brain regions are involved in higher order object perception

2020 ◽  
Author(s):  
Sophia Nestmann ◽  
Daniel Wiesen ◽  
Hans-Otto Karnath ◽  
Johannes Rennig
Keyword(s):  
Object Perception ◽  
Brain Regions ◽  
Shape Perception ◽  
General Mechanism ◽  
Complex Object ◽  
List Type ◽  
Brain Areas ◽  
Visual Stream ◽  
Object Processing ◽  
Global Shape

AbstractLesions to posterior temporo-parietal brain regions are associated with deficits in perception of global, hierarchical shapes, but also impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies and lesion patterns observed in patients with simultanagnosia and agnosia for object orientation suggest similar brain regions to be involved in perception of global shapes and processing of objects in atypical (‘non-canonical’) orientation. In a localizer experiment, we identified individual temporoparietal brain areas involved in global shape perception and found significantly higher BOLD signals during the processing of non-canonical compared to canonical objects. In a multivariate approach, we demonstrated that posterior temporo-parietal brain areas show distinct voxel patterns for non-canonical and canonical objects and that voxel patterns of global shapes are more similar to those of objects in non-canonical compared to canonical viewing conditions. These results suggest that temporo-parietal brain areas are not only involved in global shape perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting specific dorsal contributions in more demanding viewing conditions.HighlightsPosterior temporo-parietal brain areas in the TPJ region that are involved in global shape perception are significantly involved in object perceptionIndividual global shape TPJ ROIs identified with a specific localizer experiment prefer objects in non-canonical over objects in canonical orientationsUnivariate activations and multivariate voxel patterns in global shape TPJ ROIs distinguish canonical and non-canonical object presentations

scholarly journals Local motion versus global shape in biological motion: A reflexive orientation task

2010 ◽  
Vol 10 (7) ◽  
pp. 786-786
Author(s):  
M. Hirai ◽  
D. R. Saunders ◽  
N. F. Troje
Keyword(s):  
Biological Motion ◽  
Local Motion ◽  
Global Shape ◽  
Orientation Task ◽  
Motion Versus

Auroral event detection using spatiotemporal statistics of local motion vectors

2013 ◽  
Vol 24 (3) ◽  
pp. 175 ◽  
Author(s):  
Qian WANG ◽  
Jimin LIANG ◽  
Zejun HU
Keyword(s):  
Event Detection ◽  
Local Motion ◽  
Motion Vectors
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