The effects of neonatal striate lesions and visual experience on form discrimination in the rat.

Abstract

In two experiments the behaviour of light-and dark-reared infant-and adult-operated striate rats was compared on four discrimination tasks and a variety of related transfer and discrimination reversal tests. Infant-operated Tats learned all of the discriminations significantly faster and with less failure than did adult-operated animals. Post-operative rearing condition was not found to play a significant role in this performance difference due to age of operation. Though results of transfer tests for neonatal striate animals were comparable to those of controls, results of initial discrimination (and reversal) revealed significant differences in performance between infant operates and control groups. These results are discussed in terms of specification of the nature of the partial "recovery" of sensory and non-sensory functions by the neonatal operate.THE EFFECT OF ABLATION of the visual neocortex on form discrimination seems relatively clear. Although there is evidence that striate rats (Cowey & Weiskrantz, 1971; Mize, Wetzel & Thompson, 1971), cats (Spear & Braun, 1969), and primates (Pasik, Pasik, & Schilder, 1969) can respond to some aspects of contour information under optimal conditions, and with extensive post-operative training, most form and pattern discriminations cannot be learned by striate rat, cat, or primate (Lashley, 1935; Kliiver, 1941;Smith, 1938). Some studies, however, have not yielded the impairments cited above. These appear to show that large, appropriately placed sensory lesions result in little or no deficit if the operations are performed when die animals are very young. The observation that animals operated on in infancy show substantially less impairment than animals operated on as adults has been reported by a number of investigators, using several different species and lesions (e.g., Stewart & Riesen, 1972). For example, striate cats operated on within a few days of birth can discriminate patterns and forms as well as normals when tested at maturity (Doty, 1961; Wetzel, Thompson, Horel, & Meyer, 1965). Bauer and Hughes (1970) have tested the depth

The effect of bias-rearing on transfer after form discrimination training in the rat

“…The results of this experiment provide little evidence of anomalous transfer as described by Dodwell (1965Dodwell ( , 1970. This replicates similar findings by Tees (1975) and Tees et a1. (in press).…”

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

“…The effect of pen versus cage rearing of kittens on maze learning but not on pattern discrimination is parallel to the effects of early enrichment in rats. Enriched rearing does not attenuate the effects of visual decortication on pattern discrimination in rats (Bland & Cooper, 1969Tees, 1975), but enriched early experience consistently reduces the number of errors that both normal rats and rats with posterior neocortical lesions make in learning maze problems (Schwartz, 1964;Smith, 1959;. In the present experiment the effect of early enrichment on maze learning was of about the same size for the controls as for the operated kittens.…”

“…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). The purpose of the present experiment was to determine whether rearing in an environment full of opportunity for visuomotor coordination would attenuate or eliminate the detrimental effects of perinatal damage to the visual cortex on maze learning and pattern vision that are seen in cats reared in laboratory cages.…”