Recovery from early cortical damage in rats, VII. Comparison of the behavioural and anatomical effects of medial prefrontal lesions at different ages of neural maturation.

Rats with removal of the medial prefrontal (mPFC) cortex at days 3, 6, 9, 15, or 30 were compared behaviourally and anatomically to littermate controls. In contrast to adult operates, mPFC lesions at all young ages led to the development of an abnormally thin cortical mantle. In addition, although there was an obvious cavity in brains examined in the early postoperative period, the brains of animals with lesions at day 9 or 15 had no lesion cavity in adulthood as part of the cortex appeared to regrow. The differential anatomical consequences of the lesions at days 9 and 15 was correlated with a differential behavioural outcome as well. Thus although rats in all young lesion groups showed a milder behavioural syndrome than rats with comparable lesions in adulthood, the functional outcome was best for animals with lesions at 9 days of age.