Contrast-sensitive perceptual grouping and object-based attention in the laminar circuits of primary visual cortex

Abstract

Recent neurophysiological studies have shown that primary visual cortex, or V1, does more than passively process image features using the feedforward filters suggested by Hubel and Wiesel. It also uses horizontal interactions to group features preattentively into object representations, and feedback interactions to selectively attend to these groupings. All neocortical areas, including V1, are organized into layered circuits. We present a neural model showing how the layered circuits in areas V1 and V2 enable feedforward, horizontal, and feedback interactions to complete perceptual groupings over positions that do not receive contrastive visual inputs, even while attention can only modulate or prime positions that do not receive such inputs. Recent neurophysiological data about how grouping and attention occur and interact in V1 are simulated and explained, and testable predictions are made. These simulations show how attention can selectively propagate along an object grouping and protect it from competitive masking, and how contextual stimuli can enhance or suppress groupings in a contrast-sensitive manner.

Attention in hierarchical models of object recognition

“…However, there are other ideas that are not captured by the UNI framework, either because they describe the neurobiological processes at a more detailed level than is provided by the UNI framework, or because they make use of information from sources that fall outside the framework, such as visual context. Grossberg and Raizada (2000) and Raizada and Grossberg (2001), for instance, proposed a model of attention and visual grouping based on biologically realistic models of neurons and neural networks. Their model relies on grouping edges within a laminar cortical structure by synchronous firing, allowing it to extract real as well as illusory contours.…”

The complementary brain: unifying brain dynamics and modularity

“…Recent modeling work predicts some of the cells and circuits that are proposed to carry out these complementary types of matching. For example, recent modeling has suggested how top-down sensory matching is controlled in visual cortex, notably from cortical area V2 to V1, and by extension in other sensory and cognitive neocortical circuits 53,54 . This top-down circuit is part of a larger model of how bottom-up, top-down, and horizontal interactions are organized within the laminar circuits of visual cortex; see Figure 5.…”

“…For example, when ratio processing and normalization occur during visual perception, they help to control brightness constancy and contrast 15,16 as well as perceptual grouping and attention 53,54,84,85 . At higher levels of cognitive processing, these mechanisms can provide a neural explanation of the 'limited capacity' of cognitive short-term memory 68 .…”

Predictions of a model of spatial attention using sum- and max-pooling functions

“…Such a case was not discussed in earlier models of attention and the model of Reynolds et al [31] predicts a bias similar to our model using the -pooling. Comparisons with other models that are able to simulate the interactions among stimuli under di erent attentional conditions [13,6] are di cult, because neither a quantitative comparison with the experimental data discussed here nor an investigation of spatial pooling was made.…”