The Necessity of Amblyopia

Abstract

A general property of nervous system development is that correlated activity is used to organize topographic projections. This correlated activity is typically produced by electrical coupling of adjacent neurons; however, electrical coupling is not possible for retinal ganglion cells in separate eyes that need to be precisely mapped to the same place in the brain. This forces the visual system to rely on environmental stimuli to produce the correlated activity that drives the development of binocularity, with amblyopia as necessary consequence when visual experience is abnormal. The characteristic visual deficits in both the amblyopic and the sound eyes can be understood in the context of these normal developmental processes. The auditory system provides another example—where precise connections between paired sense organs must rely on environmental stimuli for normal development—in which the analogous condition of amblyaudia occurs.