National Geographic

in the recent issue on memory:

in the chirps and twitters of pocket-sized birds, Fernando Nottebohm heard the anthem of a brain-science revolution. The Rockefeller University biologist discovered that adult canaries do something a century of neuroscience dogma declared impossible: They generate new neurons to replace lost brain cells. Replacement peaks during peak memory load -- when birds learn new songs, find new food sources, or meet new social partners. Other researchers have extended Nottebohm's findings, confirming that mammals, including humans, also make new neurons. "With luck and much effort," Nottebohm says, "the simple insight I got from studying how birds learn their songs will help us find the means to repair broken brains."