Early undernutrition and later hippocampal damage. I. DRL performance in rats

Rats from dams that were well fed or underfed (50% food reduction) during lactation received either large lesions of the dorsal hippocampus of sham operations at sexual maturity. The animals then were tested on an increasing series of DRL reinforcement schedules. As expected, rats with lesions performed worse than those with sham operations. The two sham-operated groups generally performed comparably. However, the underfed rats with lesions, although impaired, performed significantly better than the well-fed rats with lesions in efficiency and responses per reinforcement, especially on the higher-valued DRL schedules. These findings show that early nutritional history can influence the later response to brain damage. The notion that the functional integrity of the late-developing hippocampus had been seriously affected by poor early nutrition, and the idea that other, less-affected parts of the brain were compensating for it from infancy on are presented to account for these findings.