Neurogenesis: Mechanisms of Change

Until the recent past, the exact mechanism of the brain’s reorganization, learning, and memory was unknown.  With the advent of the human genome project and its subsequent research findings, we now have a greater understanding of how genetic factors contribute to human learning. The draft sequence of the human genome provides us a fundamental roadmap to understanding how the brain stores information beginning from at the genetic level which alters neural networking (our cognitive faculties), and culminates in behavioral change.  In upcoming articles, I’ll shine a light on various mechanisms of change beginning with neurogenesis.

Neurogenesis

In the past, it was thought that the brain did not create new brain cells after early childhood development.  Scientists were convinced that humans were born with a set of brain cells that steadily decrease as we age. Research at the Salk Institute found that patients as mature as 72 were actually creating new brain cells. The formation of new brain cells is termed neurogenesis.  Furthermore, the Salk Institute’s research revealed that mice that were stimulated environmentally – for instance made to run – produced more new cells than did their counterparts who were sedentary.  This growth was witnessed significantly in the hippocampus, the brain’s center for memory and learning.

While Dr. Fred Gage of the Salk Institute found neurogenesis commonplace, he did not know whether the new cells became functional neurons taking an active role in the brain to aid in learning or memory until it was revealed in later research that these cells do indeed become active neurons that grow axons for communication between other neurons and produce dendrites to receive more messages from other neurons.

Use it or lose it!

This finding presents possibility that the mature brain may be more flexible and dynamic than had previously been thought. Experience seems to shape this flexibility – we have a use it or lose it proposition.  This new growth may be due to the brain’s need to replace dying cells. However, Dr. Gage says, “Another possibility is that young neurons provide a greater degree of plasticity to the mature brain. This enhanced plasticity would become apparent from the integration of new functional units whose connectivity may be shaped by experience.”

Dr. Gage’s work coincides with our current understanding of neuroplasticity and is but one wonderful example of how the brain grows and adapts to environmental challenges.