Effects of visual deprivation on the development of the monkey's lateral geniculate nucleus.

Abstract

SUMMARY1. We have studied the physiological properties of cells in the deprived layers of the lateral geniculate nucleus (l.g.n.) in monkeys monocularly deprived from birth for up to 27 weeks, and compared them with results from the non-deprived layers in the same animals and in a series of normal animals.2. Despite the relative shrinkage of cell bodies in the deprived layers, units were easily isolated, were visually responsive and could readily be classified as linear (X) or non-linear (Y) by means of tests of spatial summation. The laminar distribution of cell types and the proportion of Y cells did not seem to be affected by deprivation.3. The patterns and latencies of discharge produced by contrast-reversing gratings did not differ grossly between deprived and non-deprived cells. The peak firing frequencies for drifting gratings were also similar. The degree of surround antagonism (though very variable from cell to cell) seemed unaffected by deprivation.4. Most surprising of all, there was little or no deficit in the spatial resolution of the receptive fields of deprived cells. Recordings were always taken ipsilateral to the deprived eye, and neural 'acuity' tended to be slightly lower in the deprived laminae than the non-deprived. However, this nasal/temporal asymmetry in spatial resolution was not obviously more pronounced than in normal animals.5. Neural 'acuity' was not abnormally low in either contralateral or ipsilateral layers in the l.g.n. of an animal binocularly deprived from birth until a year of age.6. We have not examined chromatic properties or temporal characteristics adequately to say whether they are affected by deprivation.7. Paradoxically, although the post-natal maturation of visual acuity in normal monkeys seems to be mainly limited by peripheral factors, deprivation (which causes a profound defect of behavioural acuity) does not seem to interfere substantially with physiological development of the retina or the geniculate nucleus.

Is the Cortical Deficit in Amblyopia Due to Reduced Cortical Magnification, Loss of Neural Resolution, or Neural Disorganization?

“…Initially, animal studies (Eggers and Blakemore, 1978;Blakemore and Vital-Durand, 1986;Movshon et al, 1987;Crewther and Crewther, 1990) have sought to provide an explanation for amblyopia solely in terms of V1 processing as it is here where the competitive interaction between the eyes occurs (Blakemore and Eggers, 1978;Blakemore and Vital-Durand, 1992). There is now a consensus that extrastriate processing is also affected because of the wide range of visual functions affected (Levi, 1991;Levi et al, 1997;Simmers et al, 2003Simmers et al, , 2005Ho et al, 2006;Husk et al, 2012), the limited range of V1 neurophysiological deficits (Levi, 1991;Levi et al, 1997;Kiorpes et al, 1998;Kiorpes and McKee, 1999;Simmers et al, 2003Simmers et al, , 2005Ho et al, 2006;Husk et al, 2012), and the extent of the human fMRI cortical deficit (Barnes et al, 2001;Li et al, 2007b).…”

Organization and post‐natal development of the monkey's lateral geniculate nucleus.

“…One factor that might contribute to the gradual improvement in spatial resolution of l.g.n. cells is the rise in maximum Table 2 of Blakemore & Vital-Durand (1986). The triangles (filled for the left eye, open for the right) show the acuity for the best cell in each sample.…”

The Influence of Binocular Visual Deprivation on the Development of Visual-Spatial Attention

“…For all affected visual functions, the deficits are largest when the deprivation began at birth. Studies of monkeys indicate that binocular deprivation exerts its effect at the level of the striate cortex and beyond: there are no changes in photoreceptors (Hendrickson & Boothe, 1976) in the electroretinogram (Crawford, Blake, Cool, & von Noorden, 1975), or in the physiological properties of neurons in the lateral geniculate nucleus (Blakemore & Vital-Durand, 1986;Boothe, Dobson, & Teller, 1985). In contrast, striate neurons respond sluggishly, are poorly tuned, have receptive fields that are abnormally large, and are less likely than normal to be driven by both eyes (Crawford et al, 1975;Crawford, Pesch, von Noorden, Harwerth, & Smith, 1991;reviewed in Maurer & Lewis, in press).…”