The Infinite Mind

Presents information on nerve cells growing in tissue taken from the brains of elderly patients who died of cancer. Detection from the hippocampus; Patients given a radioactive tag called bromodeoxyuridine that highlights dividing cells; Possibility that cells could be replaced by young neurons.

By Jamie Talan, published on March 01, 1999

NEUROLOGY

It's been one of biology's most vexing and long-held tenets: that the number of neurons in our brains is fixed at birth and we can't generate any more. Finally, that diehard belief is being overturned. Scientists at California's Salk Institute have discovered new nerve cells growing in tissue taken from the brains of elderly patients.

"We've always learned that the brain cannot self-renew," says Salk neurobiologist Fred Gage, Ph.D. "This suggests that the brain can make new neurons." The developing cells were detected in the hippocampus, a brain area known to regulate learning and memory. Gage and colleagues from the Sahlgrenska University Hospital in Sweden made their remarkable finding when examining brain tissue from older adults who had died of cancer. These patients had been given a radioactive tag called bromodeoxyuridine (BrdU) that highlights dividing cells, such as tumor cells. But the scientists noted non-cancerous cells in the brain marked with BrdU, meaning that these neurons must have been dividing--and growing--as well.

No one knows whether these neurons could be functional. Still, the news offers hope that the aging brain could renew itself when old cells become damaged or die, says Gage. It's also possible that these cells could be replaced by young, thriving neurons. If scientists can coax the new cells to produce crucial neurotransmitters, they may have the ultimate treatment for illnesses--such as Alzheimer's and Parkinson's diseases--that tamper with mental ability.

PHOTO (COLOR): The Infinite Mind