Finding reverses long-held beliefs and has implications for designing therapies
PRINCETON, N.J. -- In a finding that eventually could lead to new methods for treating brain diseases and injuries, Princeton scientists have shown that new neurons are continually added to the cerebral cortex of adult monkeys. The discovery reverses a dogma nearly a century old and suggests entirely new ways of explaining how the mind accomplishes its basic functions, from problem solving to learning and memory.
Elizabeth Gould and Charles Gross report in the Oct. 15 issue of Science that the formation of new neurons or nerve cells -- neurogenesis -- takes place in several regions of the cerebral cortex that are crucial for cognitive and perceptual functions. The cerebral cortex is the most complex region of the brain and is responsible for highest-level decision making and for recognizing and learning about the world. The results strongly imply that the same process occurs in humans, because monkeys and humans have fundamentally similar brain structures.
"This is an absolutely novel result," says William T. Greenough, director of the neuroscience program at the University of Illinois' Beckman Institute. "These data scream for a reanalysis of human brain development."
The traditional view among neuroscientists has been that the primate brain is different from other organs in that it is not capable of repairing itself or growing new cells, that no new neurons are added to the brain in maturity. This dogma has gradually eroded in the last decade as evidence accumulated for neurogenesis in several evolutionarily older parts of the brain such as the olfactory system and the hippocampus, which is believed to play role in memory formation. In the last year, Gould and her colleagues helped this erosion by proving neuro-genesis in the hippocampus of several types of monkeys.