Integration of contours: new insights.

Psychophysical, neurophysiological and anatomical research of the last few years has converged on a new explanation of how the components of a contour become integrated. Borrowing from the Gestalt rules of good continuation, this research suggests that components of a curved contour become integrated when the alignment follows specific rules. Here, we review some of the behavioral, anatomical and physiological findings that support the notion of an 'association field' that integrates the outputs of neurons through the use of long-range lateral connections. These results provide an interesting insight into how the information from arrays of neurons distributed across the visual field might be integrated. What emerges is a new concept of a 'receptive field', in which the output of a neuron is a time-dependent, complex combination of feedforward, feedback and lateral connections that produce a rich description of the visual world at early stages of visual processing.