The integration of auditory and visual stimuli is crucial for recognizing objects, communicating effectively, and navigating through our

Attention depends on figure-ground organization: figures draw attention, while shapes of the ground tend to be ignored. Recent research has demonstrated mechanisms of figure-ground organization in the visual cortex, but how they relate to the attention process remains unclear. Here we show that the influences of figure-ground organization and volitional (top-down) attention converge in single neurons of area V2. While assignment of border ownership was found for attended as well as for ignored figures, attentional modulation was stronger when the attended figure was located on the neuron's preferred side of border ownership. When the border between two overlapping figures was placed in the receptive field, responses depended on the side of attention, and enhancement was generally found on the neuron's preferred side of border ownership. This correlation suggests that the neural network that creates figure-ground organization also provides the interface for the topdown selection process.Perception tends to segregate visual images into figures and ground, and process the figure regions, but not the ground regions (Fig. 1). 1,2 Apparently, the system is able to group the visible borders at an early stage to configurations that are likely to be objects and process this information with priority. Objects can be selected by spatial filtering when they are separated ('spotlight of attention', Fig. 2a), but such a mechanism fails when objects are partially occluded by others as in everyday images. When trying to select the bottom square in Figure 2b for example, such a mechanism would select contours in the form of an L rather than a square. Observers generally perceive the square-not the L. Apparently, the visual system first subtracts the contours of the occluding object, to use only the remaining contours for further analysis, acknowledging that information is missing (Fig. 2c). Thus, an essential step in the interpretation of images is the correct assignment of the visible borders (contours, edges) to foreground regions. 3,4 Regions of occluded objects are bounded by two types of contour, those that are inherently related to the object (intrinsic contours), and those formed accidentally by interposition of another object (extrinsic contours). 3 Only the intrinsic contours should be processed together for shape recognition; extrinsic contours should be excluded. Single cell recordings from monkey visual cortex have shown that assignment of border ownership occurs at stages as early as areas V1 and V2. 5-7 Neurons in V2 are also influenced by top-down attention. 8-12 How these two processes are related is not clear. Is figure-ground organization the result of selective attention, or is it an independent process? If it is independent, as we shall argue, what is its role in the deployment of attention? Does it enable the attention process to select contours according to border ownership (interface hypothesis), or is attentional modulation determined merely by the distance of a contour from the focus of attentio...

Sugihara T, Qiu FT, von der Heydt R. The speed of context integration in the visual cortex.

No abstract

An object viewed from different angles can be recognized and distinguished from similar distractors after the viewer has had experience watching it rotate. It has been assumed that as an observer watches the rotation, separate representations of individual views become associated with one another. However, we show here that once monkeys learned to discriminate individual views of objects, they were able to recognize objects across rotations up to 60 degrees , even though there had been no opportunity to learn the association between different views. Our results suggest that object recognition across small or medium changes in viewing angle depends on features common to similar views of objects.