Primitives for motion segmentation in the retina

The center surround structure of ganglion cells receptive fields is suited for edge detection, a first step towards image segmentation. However, in a dynamical visual scene with moving, textured objects, it is less clear how the retina represents the local boundaries of these objects. Here, we show that the spatial selectivity of ganglion cells changes during their responses to a moving object. Specific cell types only respond to contrast changes near the edges of the moving object, while being insensitive to changes in other parts of their receptive field. Using a non-linear model to reproduce this result, we could isolate the mechanism responsible for this selective representation. These types of ganglion cells represent selectively textures only when they are near moving edges, and may thus provide useful primitives for motion segmentation.