Morphometry of the effect of increased experience and training on synaptic density in area CA3 of the rat hippocampus.

A morphometric analysis of the effect of differential experiences on synapses was performed in area CA3 of the rat hippocampus. Two methods of quantitation that used a superimposed lattice grid were employed. In the first method squares overlying synapses were measured as a proportion of the total number of squares scanned; in the second method intersections of lattice lines with synapses were counted as a proportion of the total length of lines. Both measures showed that rats which were housed in an enriched environment and received 10 weeks of training had a significant increase in total area of synaptic contacts compared to both nonenriched controls and a croup with increased motor activity.