Reversal of the physiological effects of monocular deprivation in kittens: further evidence for a sensitive period

Abstract

2. Kittens were monocularly deprived until various ages, from 5 to 14 weeks, at which time reverse suturing was performed: the initially deprived right eye was opened and the left eye closed for a further 9 weeks before recording from the visual cortex.3. Reverse suturing at 5 weeks caused a complete switch in ocular dominance: every cell was dominated by the initially deprived right eye. Reverse suturing at 14 weeks, however, had almost no further effect on ocular dominance: most cells were still driven solely by the left eye. Animals reverse sutured at intermediate ages had cortical neurones strongly dominated by one eye or the other, and they were organized into clear columnar groups according to ocular dominance.4. Thus, between 5 weeks and 4 months of age, there is a period of declining sensitivity to both the effects of an initial period of monocular deprivation and the reversal of those effects by reverse suturing.5. The small proportion of binocular cells in reverse sutured kittens (which have never had simultaneous binocular vision) often differed considerably in their receptive field properties in the two eyes. In particular, if the cells were orientation selective in both eyes the two preferred orientations could differ by up to 70°.6. The relative importance of innate and environmental contributions to the properties of cortical cells is discussed.

Rapid recovery from the effects of early monocular deprivation is enabled by temporary inactivation of the retinas

“…These findings establish 7 d of early MD in mice as a useful protocol to investigate strategies for reversing ocular dominance plasticity and promoting recovery from amblyopia. It has been known for many years from work in kittens and monkeys that deprivation-induced synaptic depression can be reversed if normal vision is restored in the weak (amblyopic) eye and the fellow eye is occluded (11,12). However, gains in the amblyopic eye often come at the expense of vision in the fellow eye, may be temporary, and are rarely accompanied by improvement in binocularity (9,(17)(18)(19).…”

“…This "reverse occlusion" approach has been validated in animals (11,12) and represents the cornerstone of current treatment (patching therapy) of human amblyopia (13)(14)(15)(16). However, this treatment has well-known limitations that include poor compliance, potential loss of vision through the newly patched eye, failure to recover binocular vision, and a declining treatment efficacy with age (15,(17)(18)(19)(20)(21).…”

Neural mechanisms of recovery following early visual deprivation

“…The extent to which the initial effects of deprivation can be reversed and the speed of the changes depend upon the age at which reverse occlusion begins (Blakemore & Van Sluyters 1974;Movshon 1976a;Blakemore et al 1978Blakemore et al , 1981. Indeed, it has been argued that the temporal profile of the declining ability to reverse prior deprivation-induced effects represents a separate critical period for recovery (Daw 1998(Daw , 2002(Daw , 2003Lewis & Maurer 2005).…”

Structural and functional recovery from early monocular deprivation in adult rats

“…Indeed, studies in animals have shown that monocular deprivation (MD) impairs visual cortical responses to the deprived eye and affects axonal morphology and dendritic spine density only if performed during a critical period of postnatal development (2)(3)(4)(5)(6). The ability to recover from the deficits induced by MD declines with age; reopening the previously deprived eye or reverse lidsuturing (RS) in young animals results in full recovery of ocular dominance, but these procedures become progressively less effective with age and are practically ineffective in the adult (7)(8)(9). Recovery from the amblyopic effect of MD is also progressively less efficient during development.…”