Two symmetry breaking mechanisms for the development of orientation selectivity in a neural system

TL;DR

This paper explores two distinct symmetry breaking mechanisms in neural systems that develop orientation selectivity, highlighting how nonlinear interactions lead to biologically consistent columnar patterns.

Contribution

It identifies and compares two mechanisms of symmetry breaking in neural development, emphasizing the role of nonlinearity in forming realistic orientation columns.

Findings

Only the nonlinear spontaneous mechanism produces columnar patterns.

The competition-based mechanism does not lead to column formation.

Orientation selectivity emerges through symmetry breaking in receptive fields.

Abstract

Orientation selectivity is a remarkable feature of the neurons located in the primary visual cortex. Provided that the visual neurons acquire orientation selectivity through activity-dependent Hebbian learning, the development process could be understood as a kind of symmetry breaking phenomenon in the view of physics. The key mechanisms of the development process are examined here in a neural system. Found is that there are at least two different mechanisms which lead to the development of orientation selectivity through breaking the radial symmetry in receptive fields. The first, a simultaneous symmetry breaking mechanism, bases on the competition between neighboring neurons, and the second, a spontaneous one, bases on the nonlinearity in interactions. It turns out that only the second mechanism leads to the formation of a columnar pattern which characteristics accord with those observed in an animal experiment.