Simulation studies of the role of intracortical inhibition in the formation of sensitivity to cross-shaped figures.

The receptive fields of detector neurons for cross-shaped figures in the visual cortex were modeled in conditions of blockade of intracortical inhibition. The tuning of simulated neurons was compared with and without inhibition in the receptive field. In a simulated detector with convergence from two orientation detectors, acute tuning to the cross widened in the absence of inhibition, becoming invariant to the shape and orientation of the cross. A detector based on the disinhibition mechanism lost cross sensitivity when inhibition was blocked and became a detector for the orientation of a single bar. A model of a receptive field in which the inhibitory zones mask the tuning to a cross-shaped figure and in which blockade of inhibition affects only sensitivity is also proposed. We identified which of the properties of receptive field (configuration, location, zone weightings) allow them to simulate the properties of cat visual cortex field 17 neurons, these being sensitive to the shape and orientation of cross-shaped figures.