Responses in early visual areas to contour integration are context dependent

@article{Qiu2016ResponsesIE,
  title={Responses in early visual areas to contour integration are context dependent},
  author={Cheng Qiu and Philip C. Burton and Daniel J. Kersten and Cheryl A. Olman},
  journal={Journal of Vision},
  year={2016},
  volume={16}
}
It has been shown that early visual areas are involved in contour processing. However, it is not clear how local and global context interact to influence responses in those areas, nor has the interarea coordination that yields coherent structural percepts been fully studied, especially in human observers. In this study, we used functional magnetic resonance imaging (fMRI) to measure activity in early visual cortex while observers performed a contour detection task in which alignment of Gabor… 

Figures from this paper

Perceptual integration and attention in human extrastriate cortex
TLDR
FMRI measurements and wide-field brain mapping methods provide evidence that some area beyond V1 might be the likely candidate for the site of crowding, thus supporting the view of visual crowding as a mid-level visual phenomenon.
Normalization by orientation anisotropy in human V1-V3
TLDR
A computational model is proposed, in which responses are normalized not by the sum of the contrast energy, but by the orientation anisotropy, computed as the variance in contrast energy across orientation channels.
Integration of contours defined by second-order contrast-modulation of texture
TLDR
It is concluded that humans can integrate second-order contours, even when they are curved, however there is however reduced performance compared to first- order contours.
Fragmented ambiguous objects: Stimuli with stable low-level features for object recognition tasks
TLDR
A set of line segment-based images that are matched for luminance, contrast, and orientation distribution but result in a range of object and non-object percepts, and identify a set of 100 images that all have the same low-level properties but cover a rangeof recognizability and semantic stability.
Distinct effects of contour smoothness and observer bias on visual persistence
TLDR
The strong modulatory effects of contour smoothness on persistence are due to the sustained reverberation of local and global contour-binding mechanisms in visual cortex, which form an important basis of perceptual continuity and stable object perception.
...
...

References

SHOWING 1-10 OF 131 REFERENCES
Contour Saliency in Primary Visual Cortex
Perceptual grouping and the interactions between visual cortical areas
The Representation of Illusory and Real Contours in Human Cortical Visual Areas Revealed by Functional Magnetic Resonance Imaging
TLDR
Physiological signals obtained from human visual cortex while subjects viewed different types of contours suggest a role in surface perception for this lateral occipital region that includes V3A, V4v, V7, and V8 and finds evidence for overlapping sites of processing.
Perceptual Organization of Local Elements into Global Shapes in the Human Visual Cortex
Top-down Modulations in the Visual Form Pathway Revealed with Dynamic Causal Modeling
TLDR
The aim of this study was to characterize top-down effects that originate in the visual cortex and that are involved in the generation and perception of form, and showed that recognizable stimuli cause larger activations in anterior visual and frontal areas.
Cortical feedback improves discrimination between figure and background by V1, V2 and V3 neurons
TLDR
It is shown that feedback connections facilitate responses to objects moving within the classical receptive field; enhance suppression evoked by background stimuli in the surrounding region; and have the strongest effects for stimuli of low salience.
Contour integration in striate cortex. Classic cell responses or cooperative selection?
TLDR
The results are interpreted as selective cooperation and mutual facilitation of cortical V1 cells, thereby supporting the saliency of borders and contours in perception of visual scenes.
Cortical Regions Involved in Perceiving Object Shape
TLDR
Results suggest that common regions in the LOC are involved in extracting and/or representing information about object structure from different image cues, including contours, shading, and monocular depth cues.
...
...