The effect of alcohol on neurogenesis. As shown in the left panel, a single 5g/kg dose of alcohol causes a 40-percent decrease in cell proliferation (newly dividing bromodeoxyuridine [BrdU+]–marked cells) 5 hours later. The right panel shows calculated neurogenesis based on the number of surviving cells 4 weeks after alcohol exposure. By this time, 70 percent of surviving cells (calculated as a percentage of the number of surviving cells in the control group) have migrated and differentiated into neurons, 20 percent have differentiated into glia, and about 10 percent are unclassified. These percentages were multiplied by the number of BrdU+ cells surviving at 4 weeks (right y axis), showing the decrease in neurogenesis that resulted from decreased proliferation.