Latent Impact of Abnormal Visual Experience: Early Abnormal Vision Influences Impact of Subsequent Monocular Deprivation

Abstract

In vision research, monocular deprivation (MD) achieved through eyelid closure is used as a method to replicate the impact of amblyopia in humans and is commonly employed to explore visual system plasticity. Following a period of MD early in development, cats later manifest discernible alterations in the dorsal lateral geniculate nucleus (dLGN) and the primary visual cortex (V1). These alterations are characterized by a reduction of soma size and loss of neurofilament in the layer of the dLGN connected to the deprived eye. Additionally, there is an absence of activity in binocular cells of when the deprived eye is stimulated. Importantly, these changes can only be induced during a critical period occurring early in development, marked by heightened plasticity peaking before the first two postnatal months in cats. This plasticity gradually diminishes into early adulthood, reaching a point where the substantial alterations caused by a period of MD can no longer be induced. The focus of the current investigations explores modulations of the profile of the classical critical period through multiple instances of abnormal visual experiences. This was achieved through investigations of the influence of an early and transient MD or monocular inactivation on the alterations in soma size and reduction of neurofilament in the dLGN resulting from a subsequent period of MD near the end of the critical period. The findings reveal an influence of early monocular vision on the impact of later MD when the opposite eye is initially deprived or inactive. Moreover, there is a subtle influence when the same eye is subjected to both instances of monocular vision. These findings suggest the potential for a latent influence of early monocular vision on the capacity for plasticity later in life.