Visual experience, unilateral cortical lesions, and lateralization of function in rats

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Measured the effects of early visual experience and later unilateral neocortical lesions on the behavior of 30 male hooded Long-Evans rats in an open-field, 17-arm spatial maze and on a visual field or perimetry test. 30 Ss were formed into 6 groups–3 light-reared (LR) and 3 dark-reared (DR)–of 5 Ss each in order to receive right-, left-hemisphere, or sham neocortical lesions. The comparison of behavior observed in the open field revealed that LR Ss with right-hemispheric lesions were more active and reared more than any of the other Ss. On the radial-maze task, in which 8 of 17 arms were baited, all Ss with lesions performed less effectively than did sham-operated Ss. The effect of the lesions was significantly greater for LR than for DR Ss. Perimetry testing revealed that, although the lesioned Ss did react to stimuli throughout their visual field, some contralateral neglect was evident in both LR and DR Ss; the lesions had a greater impact on orientation behavior of LR Ss, however. No evidence emerged of any functional asymmetry following the unilateral cortical lesions. Findings are discussed in terms of V. H. Denenberg's (1981) hypothesis about cerebral and functional asymmetry in the rat. (37 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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