Lateral connectivity as a scaffold for developing orientation preference maps

In the visual cortex of the cat and ferret, it is established that orientation selectivity is the consequence of experience-dependent plasticity. Recent experiments, however, indicate that the layout of orientation maps is remarkably stable and experience-independent. We present a model to account for these seemingly paradoxical results. In this model, a scaaold consisting of anisotropic lateral connections is laid down in horizontal circuitry prior to visual experience. These lateral connections provide an experience-independent framework for the developing orientation map by inducing broad orientation tuning. Adult-like, sharp orientation tuning emerges as the result of experience-dependent plasticity of the feedforward connections. This plasticity is modeled by the BCM synaptic plasticity rule in a natural scene environment. This model simultaneously satisses the requirements of plasticity and stability that are seen in experiment. In addition, this model provides an explanation of the phenomenon where two eyes without common visual experience develop similar orientation maps.