The development of vision in cats after extended periods of dark-rearing

Abstract

The time course of development of visual acuity for square wave gratings was measured behaviourally in a number of cats that were reared in total darkness until they were either 4 (5 cats) or 6 (1 cat) months of age. Less extensive measurements were also made on animals reared in a similar manner until they were either 1 1/2 or 10 months old. Initially, all the animals appeared to be blind, but signs of vision became evident after periods of time in an illuminated environment that ranged from a few days, in the case of animals dark-reared for only 1 1/2 to 4 months, to 1 to 2 months for those animals that were deprived for 6 months or more. Thereafter, visual acuity as measured on a jumping stand progressively improved, reaching, in the case of animals deprived for 4 months, values that were comparable to those of normal animals (6.9 cycles/deg) after 4 months of exposure to light. The animal deprived for 6 months remained apparently blind for a month and eventually attained an acuity (5.7 cycles/deg) that was somewhat less than that of normal animals. The fact that such high acuities can be achieved after periods of binocular deprivation that extend throughout the classically defined "critical period" suggest that the effect of dark-rearing is somehow to impede the natural decline with age in the degree to which cortical neurones are susceptible to environmental modification.

Environmental Influences on Visual Cortex Development and Plasticity

“…This is confirmed by results obtained in enriched rats raised in darkness during development [63]. It is well known that rearing mammals in total darkness affects the maturation of visual cortical circuits, prolonging the duration of the critical period and impairing the process of visual acuity maturation until normal visual experience is re-established [64,65]. We found that both effects of dark rearing were completely counteracted by EE [63].…”

Vision Triggers an Experience-Dependent Sensitive Period at the Retinogeniculate Synapse

“…Greater visual cortical plasticity is found during chronic deprivation in rats, causing deficits in RF size, acuity, and orientation selectivity (Fagiolini et al, 1994). In cat, binocular deprivation (Wiesel and Hubel, 1965) and dark rearing (Timney et al, 1978) resulted in reduced visual acuity and cortical cells that were unresponsive or had poorly defined receptive field responses.…”

Nurturing brain plasticity: impact of environmental enrichment

“…Adult animals reared in darkness from birth (dark rearing, DR) display serious physiological deficits in their visual cortex, including reduced orientation and direction tuning, lower cell responsiveness, larger receptive field sizes, altered spontaneous activity, immature ocular dominance (OD) distribution and lower visual acuity (VA). [7][8][9][10] Ocular dominance plasticity refers to the rapid change in visual cortex physiology resulting from unbalanced inputs from the two eyes. Hubel and Wiesel 11,12 first reported in kittens that reducing input from one eye by lid suture (monocular deprivation, MD) during development dramatically affects the binocularity of V1, leading to a loss of cortical responses to that eye and an increase in the number of neurons preferentially driven by the open eye.…”