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 group with increased motor activity.