Remapping of Border Ownership in the Visual Cortex

Abstract

We see objects as having continuity even though the retinal image changes frequently. How such continuity is achieved is hard to understand, because neurons in the visual cortex have small receptive fields that are fixed on the retina, which means that a different set of neurons is activated every time the eyes move. Neurons in areas V1 and V2 signal the local features that are currently in their receptive fields and do not show “remapping” when the image moves. However, subsets of neurons in these areas also carry information about global aspects such as figure-ground organization. Here we carried out experiments to find out if figure-ground organization is remapped. We recorded single neurons in macaque V1 and V2 where figure-ground organization is represented by assignment of contours to regions (border ownership). We had previously found that border ownership signals persist when a figure edge is switched to an ambiguous edge by removing the context. We now used this paradigm to see if border ownership transfers when the ambiguous edge is moved across the retina. In the new position, the edge activated a different set of neurons at a different location in cortex. We found that border ownership was transferred to the newly activated neurons. The transfer occurred whether the edge was moved by a saccade or by moving the visual display. Thus, while the contours are coded in retinal coordinates, their assignment to objects is maintained across movements of the retinal image.

A neural model of border-ownership from kinetic occlusion

“…Single cell data indicate that in the case of a figure defined by luminance contrast that moves from one location on the retina to another, border-ownership signals ''remap'' (O'Herron & von der Heydt, 2013). That is, border-ownership signals transfer from B cells whose receptive fields are initially centered on the edges of the figure to those centered on the edges as the figure moves.…”

Border-ownership coding

“…O'Herron and von der Heydt (2009,2011) discovered that the border ownership signals in V2 neurons often persist for over a second when the figure-ground assignment becomes ambiguous (see Figure 9). Even more interesting, this border ownership persistence can be remapped during saccades and moves with the ambiguous displays if they jump to a new location (O'Herron & von der Heydt, 2013). These findings show that border ownership selectivity reflects a mechanism that helps to maintain a stable visual percept.…”

“…O'Herron & von der Heydt (2013) showed how this model could be extended to explain the remapping of border ownership signals.…”

“…Example displays and approximate time course of the population border ownership signal of experiments by O'Herron and von der Heydt (2009, 2013). In the figure phase of (A,B), a square is shown with one border aligned to a CRF, such that the square is on the preferred (A) or non-preferred (B) side-of-figure.…”

Border-ownership-dependent tilt aftereffect for shape defined by binocular disparity and motion parallax

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Discerning objects from their surrounds (i.e., figure-ground segmentation) in a way that guides adaptive behaviours is a fundamental task of the brain. Neurophysiological work has revealed a class of cells in the macaque visual cortex that may be ideally suited to support this neural computation: border-ownership cells (Zhou, Friedman, & von der Heydt, 2000).These orientation-tuned cells appear to respond conditionally to the borders of objects. A behavioural correlate supporting the existence of these cells in humans was demonstrated using two-dimensional luminance defined objects (von der Heydt, Macuda, & Qiu, 2005).However, objects in our natural visual environments are often signalled by complex cues, such as motion and depth order.

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