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Cue combination encoding via contextual modulation of V1 and V2 neurons

Authors Zarella MD, Ts'o DY

Received 2 February 2016

Accepted for publication 21 April 2016

Published 21 October 2016 Volume 2016:8 Pages 177—193


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 3

Editor who approved publication: Professor Margaret Wong-Riley

Supplementary video 1 shows the homogeneous stimulus for a bar orientation of 45° and motion direction of 90°.

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Mark D Zarella, Daniel Y Ts’o

Department of Neurosurgery, SUNY Upstate Medical University, Syracuse, NY, USA

Abstract: Neurons in early visual cortical areas encode the local properties of a stimulus in a number of different feature dimensions such as color, orientation, and motion. It has been shown, however, that stimuli presented well beyond the confines of the classical receptive field can augment these responses in a way that emphasizes these local attributes within the greater context of the visual scene. This mechanism imparts global information to cells that are otherwise considered local feature detectors and can potentially serve as an important foundation for surface segmentation, texture representation, and figure–ground segregation. The role of early visual cortex toward these functions remains somewhat of an enigma, as it is unclear how surface segmentation cues are integrated from multiple feature dimensions. We examined the impact of orientation- and motion-defined surface segmentation cues in V1 and V2 neurons using a stimulus in which the two features are completely separable. We find that, although some cells are modulated in a cue-invariant manner, many cells are influenced by only one cue or the other. Furthermore, cells that are modulated by both cues tend to be more strongly affected when both cues are presented together than when presented individually. These results demonstrate two mechanisms by which cue combinations can enhance salience. We find that feature-specific populations are more frequently encountered in V1, while cue additivity is more prominent in V2. These results highlight how two strongly interconnected areas at different stages in the cortical hierarchy can potentially contribute to scene segmentation.

Keywords: striate, extrastriate, extraclassical, texture, segmentation

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