Activity-Dependent Self-Organization of Orientation Preference Predicts a Transient Overproduction of Pinwheels during Visual Development
The pinwheel-like arrangement of iso-orientation domains around orientation centers is a ubiquitous structural element of orientation preference maps in primary visual cortex. Here we investigate how activity-dependent mechanisms constrain the way in which orientation centers can form during visual development. We consider the dynamics of a large class of models for the activity-dependent self-organization of orientation preference maps. We prove for this class of models that the density of orientation centers which proliferate as the map arises from a homogeneous state exhibits a universal lower bound. Due to topological constraints the density of orientation centers can only change by discrete creation and annihilation events. Consequently activity-dependent self-organization of orientation preference implies that low densities of orientation centers develop through an initial overproduction and subsequent annihilation of pinwheels. Monitoring the density of orientation centers during development therefore offers a powerful novel approach to test whether orientation preference arises by activity-dependent mechanisms or is genetically predetermined.
KeywordsOrientation Preference Nonlinear Phase Orientation Selectivity Gaussian Random Field Visual Development
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