Regeneration of Brain Cells

Brave New World of Adult Neurogenesis

Brain Neural Network

Alfred Pasieka / Science Photo Library / Getty Images

For almost 100 years, it had been a mantra of biology that brain cells or neurons do not regenerate. It was thought that all your significant brain development happened from conception to age 3. Contrary to that widely held popular belief, scientists now know that neurogenesis continuously occurs in specific regions in the adult brain.

In a startling scientific discovery made in the late 1990s, researchers at Princeton University found that new neurons were continually being added to the brains of adult monkeys. The finding was significant because monkeys and humans have similar brain structures.

These findings and several others looking at cell regeneration in other parts of the brain opened up a whole new line of research about "adult neurogenesis," the process of the birth of neurons from neural stem cells in a mature brain. 

Pivotal Research on Monkeys

Princeton researchers first found cell regeneration in the hippocampus and the subventricular zone of the lateral ventricles in monkeys, which are important structures for memory formation and functions of the central nervous system. 

This was significant but not quite as important as the 1999 finding of neurogenesis in the cerebral cortex section of the monkey brain. The cerebral cortex is the most complex part of the brain and scientists were startled to find neuron formation in this high-function brain area. The lobes of the cerebral cortex are responsible for higher-level decision making and learning.

Adult neurogenesis was discovered in three areas of the cerebral cortex:

  • The prefrontal region, which controls decision-making
  • The inferior temporal region, which plays a role in visual recognition
  • The posterior parietal region, which plays a role in 3D representation

Researchers believed that these results called for a fundamental reassessment of the development of the primate brain. Although the cerebral cortex research had been pivotal for advancing scientific research in this area, the finding remains controversial since it has not yet been proved to occur in the human brain.

Human Research

Since the Princeton primate studies, newer research has shown that human cell regeneration occurs in the olfactory bulb, which is responsible for sensory information for the sense of smell, and the dentate gyrus, a part of the hippocampus responsible for memory formation.

Continued research on adult neurogenesis in humans has found that other areas of the brain may also generate new cells, particularly in the amygdala and the hypothalamus. The amygdala is the part of the brain governing emotions. The hypothalamus helps maintain the autonomic nervous system and the hormone activity of the pituitary, which controls body temperature, thirst, and hunger and is also involved in sleep and emotional activity.

Researchers are optimistic that with further study scientists might one day unlock the key to this process of brain cell growth and use the knowledge to treat a variety of psychiatric disorders and brain diseases, like Parkinson's and Alzheimer's.

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