Visual depth perception in normal and deprived rats: effects of environmental enrichment

A proper maturation of stereoscopic functions requires binocular visual experience and early disruption of sensory-driven activity can result in long-term or even permanent visual function impairment. Amblyopia is one paradigmatic case of visual system disorder, with early conditions of functional imbalance between the two eyes leading to severe deficits of visual acuity and depth-perception abilities. In parallel to the reduction of neural plasticity levels, the brain potential for functional recovery declines with age. Recent evidence has challenged this traditional view and experimental paradigms enhancing experience-dependent plasticity in the adult brain have been described. Here, we show that environmental enrichment (EE), a condition of increased cognitive and sensory-motor stimulation, restores experience-dependent plasticity of stereoscopic perception in response to sensory deprivation well after the end of the critical period and reinstates depth-perception abilities of adult amblyopic animals in the range of normal values. Our results encourage efforts in the clinical application of paradigms based on EE as an intervention strategy for treating amblyopia in adulthood.