  In animal experiments, the observed orientation preference (OP) and ocular
dominance (OD) columns in the visual cortex of the brain show various pattern
types. Here, we show that the different visual map formations in various
species are due to the crossover behavior in anisotropic systems composed of
orientational and scalar components such as easy-plane Heisenberg models. We
predict the transition boundary between different pattern types with the
anisotropy as a main bifurcation parameter, which is consistent with
experimental observations.
