Dendritic spines analysis
At least eight to ten layer V pyramidal neurons from the visual cortex monocular region were selected from each brain for analysis utilizing light microscopy. Each of these neurons had to have an apical dendrite of at least 80μm long and exhibited full Golgi impregnation represented by a lack of floating spine heads. Each neuron underwent analysis of the apical dendrite, and following regions if present: apical oblique (branch protruding from apical dendrite), first order basilar branch (branching directly from pyramidal cell), second order basilar branch (separated from first order branch), third order basilar branch (from second order branch) and forth order basilar branch (from third order branch). A segment of at least 10μm long and at least 2μm away from bifurcations, was selected from the structures mentioned above, and analyzed based on the number of dendritic spines and morphology of dendritic spines. Each dendritic spine was categorized based on similarity to 12 categories (Figure 1) modified from those described in Irwin et al., 2002 as seen in Figure 2. All final analyses were done under 100X magnification. Length of the each segment was recorded, as well as the thickness of the segment at the starting and end points. The segment thickness was recorded to ensure that any differences in dendritic spine density was not due to differences in dendritic branch thickness.
All data collection and analyses were conducted