More Good News for Aging Brains

By Ellen Kuwana
Neuroscience for Kids Staff Writer
November 16, 1999


Research in animals such as rats, lizards, and birds has shown that new neurons are produced in the part of their brains called the hippocampus. This production of new neurons is called neurogenesis. It was a logical step for scientists to suspect that neurogenesis might also occur in adult humans. They were correct.

About a year ago, research showed that new neurons were produced in the hippocampus of human brains. Now scientists are looking at parts of the brain to see if new neurons are produced there, too. To look for new neurons, researchers use a chemical called bromodeoxyuridine, or BrdU for short. BrdU is incorporated into new cells, thus making them distinguishable from old cells. When researchers examine brain tissue, they can look for cells that contain BrdU.

Dr. Elizabeth Gould, a professor of Psychology at Princeton University, has reported (Science, October 15, 1999) that new neurons are added to other parts of the brain in adult macaque monkeys. These areas include those involved in "higher functions" such as learning, problem solving, and memory. Dr. Gould and her research group saw the generation of neurons in the prefrontal cortex, inferior temporal cortex, and the posterior parietal cortex. Each of these areas has been implicated in cognitive functions. The prefrontal region is thought to be involved in short-term memory and decision making; the inferior temporal area contributes to visual recognition (e.g., recognition of faces); and the posterior parietal cortex aids in interpreting the positions of objects in space.

There is some evidence that the new cells are functional. The cells originated in the subventricular zone, an area around the ventricles, the fluid-filled cavities deep within the brain. These cells then migrated from this area to the cortex, where they developed axons. The fact that the new cells formed axons suggests that they are functioning.

This new study indicates that neurogenesis in the brain is more widespread than previously thought. If researchers can find out how new neurons appear, what conditions are necessary for generating new neurons, what factors need to be present or what chemicals must be absent, perhaps this information can be used to fight neurodegenerative diseases. Answers to these questions may provide treatments for disorders such as Alzheimer's disease and Parkinson's disease.

The Ventricles
Image adapted from Biodidac


  1. "Neurogenesis in the Neocortex of Adult Primates," by E. Gould, A.J. Reeves, M.S.A. Graziano and C.G. Gross. Science, 15 October 1999.
  2. "Princeton University Press Release." Scientist Discover Addition of New Brain Cells in Highest Brain Area, October 14, 1999.
  3. "Science Friday Brain Update."
  4. "Do Brain Cells Regenerate?" Princeton Weekly Bulletin, April 5, 1999.

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