Early-life polysensorial stimulation and nutrition: topographic levels of susceptibility in the rat visual cortex.

The effects of environmental-nutritional interactions upon the development of the visual cortex were studied in Sprague-Dawley albino rats during lactation (5-22 postnatal days). Morphometric evaluations were assessed by measuring layer V pyramidal neurons, under camera lucida. The Golgi-Cox-Sholl technique permits quantitative studies of neurons by the precipitation of metallic mercury at random, without any selectivity. Length and frequency of dendritic segments showed significant differences due to rearing, nutrition, and topographic localization. Early environmental enrichment exerted its maximal benefits in undernourished pups, the influences being highly prominent in the lateroventral sector of the cortical plate that receives conspicuous inputs during development. These findings may provide bases for the design of clinical strategies to palliate the adverse effects of undernourishment and sensory deprivation on brain development, since their effects seem to follow pari passu the topographic sequences of cortical morphogenesis.