Increases in dendritic length in occipital cortex after 4 days of differential housing in weanling rats.

To assess the capacity for experience to induce rapid alterations in the dendritic fields of cortical neurons, male Long-Evans hooded rats aged 30-31 days were housed in either a complex environment (EC) or an individual cage (IC) for 4 days. The basilar dendrites of layer III pyramidal cells in area 17 of visual cortex were measured in Golgi-stained sections. EC rats exhibited significant increases in total dendritic length and total number of branches. This finding demonstrates that the structural modifications previously reported after 30 days in the complex environment are well underway after only 4 days.