Symmetry considerations and development of pinwheels in visual maps

TL;DR

This paper investigates the symmetry properties and development of pinwheel structures in visual cortical maps, combining statistical analysis and modeling to understand their stability and formation.

Contribution

It demonstrates that reduced symmetry involving orientation and topography is essential for pinwheel development, supported by empirical data and stability analysis in models.

Findings

Pinwheels are statistically present in monkey and cat visual cortex maps.

Coupled orientation-topography models show pinwheels are generically stable.

Reduced symmetry is crucial for the formation of pinwheel structures.

Abstract

Neurons in the visual cortex respond best to rod-like stimuli of given orientation. While the preferred orientation varies continuously across most of the cortex, there are prominent pinwheel centers around which all orientations a re present. Oriented segments abound in natural images, and tend to be collinear}; neurons are also more likely to be connected if their preferred orientations are aligned to their topographic separation. These are indications of a reduced symmetry requiring joint rotations of both orientation preference and the underl ying topography. We verify that this requirement extends to cortical maps of mo nkey and cat by direct statistical analysis. Furthermore, analytical arguments and numerical studies indicate that pinwheels are generically stable in evolving field models which couple orientation and topography.