"We believe that new brain cells help us to distinguish between memories that are closely related in space," says senior author Fred H. Gage, Ph.D., a professor in the Laboratory for Genetics at the Salk Institute and the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Diseases, who co-directed the study with Timothy J. Bussey, Ph.D., a senior lecturer in the Department of Experimental Psychology at the University of Cambridge, UK, and Roger A. Barker, PhD., honorary consultant in Neurology at Addenbrookes Hospital and Lecturer at the University of Cambridge.
When the first clues emerged that adult human brains continually sprout new neurons, one of the central tenets of neuroscience—we are born with all the brain cells we'll ever have—was about to be overturned. Although it is never easy to shift a paradigm, a decade later the question is no longer whether neurogenesis exists but rather what all these new cells are actually good for.
"Adding new neurons could be a very problematic process if they don't integrate properly into the existing neural circuitry," says Gage. "There must be a clear benefit to outweigh the potential risk."