Depth perception after infant and adult visual neocortical lesions in light‐ and dark‐reared rats

Abstract

In 2 experiments the behavior of light- and dark-reared infant- and adult-operated striate rats were compared at 20-160 days of age on a visual cliff apparatus in which the depth of the deep side could be varied. Differential depth thresholds revealed that depth discriminative ability did not develop normally following removal of the striate cortex in infancy. Further, infant-operates who were reared in darkness following their operations performed less well than their light-reared, infant-operated counterparts. The infant-operated animals, regardless of their postoperative rearing condition, performed significantly better than did adult-operated animals after comparable post-operative recovery periods and testing. The results are discussed in terms of further specification of the role played by age of operation and by the interaction between visual experience and age of operation.

Behavioral effects of early rearing conditions and neonatal lesions of the visual cortex in kittens.

“…Perhaps early enrichment helps later maze learning by increasing the sensitivity to nonvisual spatial cues, but such increased sensitivity does not permit adequate performance on the visual cliff, where only visual cues are available. This explanation of our findings is not completely satisfactory, however, since it fails to explain why rats with neonatal lesions of the visual cortex choose the shallow side of a visual cliff reliably more often than rats with comparable lesions made in adulthood (Bauer & Hughes, 1970;Tees, 1976). In any case, the results from both the pen-reared and the cage-reared kittens confirm the previous findings that relatively complete lesions of the visual cortex impair performance of cats on the version of the visual cliff used in the present study whether the lesions are made in infancy (Cornwell et al, 1978) or in adulthood (Cornwell, Overman, & Campbell, 1980;Cornwell et al, 1976).…”

“…Several studies of rats with lesions of the visual cortex indicate at least limited effects of environmental enrichment on sparing or recovery from brain damage. Rearing or rehabilitation in an enriched environment improves the maze-learning ability of rats with lesions of the visual cortex (Schwartz, 1964;Smith, 1959;Will, Rosenzweig, & Bennett, 1976;Will, Rosenzweig, Bennett, Hebert, & Morimoto, 1977), and rats with such lesions select the shallow side of the visual cliff more frequently if they are reared in the light than if they are reared in the dark (Tees, 1976). Growing up in an environment rich in opportunity for visuomotor experience does not, however, attenuate the deficit in pattern vision produced by neonatal damage of the rat's visual cortex (Bland & Cooper, 1969Tees, 1975).…”