Recovery from early cortical damage in rats. II. Effects of experience on anatomy and behavior following frontal lesions at 1 or 5 days of age.

Perinatal cortical damage is often associated with significant overall shrinkage of the remaining cortex and severe behavioral impairments. Environmental experience was manipulated in order to determine if the anatomical and behavioral effects of neonatal frontal decortication might be attenuated by rearing in a complex environment. Rats received frontal decortication on the day of birth or 5 days later and were subsequently raised, along with littermate controls, in a complex environment or in standard laboratory cages. In adulthood, the animals were tested on a battery of behavioral tests which showed that enrichment markedly attenuated the effects of the early lesions, especially for the 5-day operates, even on tests such as tongue extension that would not be expected to benefit from specific practice in the complex environment. Analysis of the remaining cortex revealed that all groups raised in the complex environment developed thicker cortex, the increase being most dramatic in the rats given lesions at 5 days of age.