October 2003

Neuroplasticity

by Dr. Christopher Kent

In a recent issue of Scientific American, Michael M. Merzenich noted, "The brain was constructed to change."[1] This challenge to the conventional worldview that the mature adult brain is stable and unchanging ‑‑ the only exception being the death of brain cells ‑‑ has profound implications for the chiropractor.

As Gage stated, "Researchers first demonstrated that the central nervous systems of mammals contain some innate regenerative properties in the 1960s and 1970s, when several groups showed that axons, or main branches, of neurons in the adult brain and spinal cord can regrow to some extent after injury."[2]

The ability of the brain to change both anatomically and functionally is known as neuroplasticity. Clifford reviewed three types:

1. Experience‑independent plasticity refers to changes which are not the result of environmental changes or influence.

2. Experience‑expectant plasticity occurs when the brain uses input from the external environment to effect normal developmental changes in its structure.

3. Experience‑dependent plasticity is when a modification to the internal or external environment produces change in a feature of the brain.[3]

Holloway explained how the brain reconfigures itself, and the implications of doing so:

"Change the input‑be it a behavior, a mental exercise...or a physical skill‑and the brain changes accordingly. Magnetic resonance imaging machines reveal the new map: different regions light up...

"[T]he brain can be extensively remodeled throughout the course of one's life, without drugs, without surgery. Regions of the brain can be taught to do different tasks if need be...This sort of thing will be a part of normal future life...healing plasticity can be driven by behavior."[1]

Vertebral subluxation may result in dysafferentation,[4] a process where aberrant afferent input results in qualitatively and quantitatively distorted perception of the external and internal environment. In 1996, I described how this could lead to dysponesis and inappropriate motor function. Today, we know the stakes are much higher‑dysafferentation may result in anatomical and functional changes in the brain itself.

Dr. Fred Barge, in his book, "One Cause, One Cure" stated that the cause of disease is "The body's inability to comprehend itself and/or it's environment."[5] Such "comprehension" is dependent upon interference‑free afferent input. This sculpts the brain, and as a result, our very sense of self.

References

1. Holloway M: "The mutable brain." Scientific American 2002;289(3):79.

2. Gage FH: "Brain, repair yourself." Scientific American 2002;289(3):47.

3. http://hcs.harvard.edu/~husn/BRAIN/vol6/p16‑20‑Neuronalplasticity.pdf

4. http://www.jvsr.com/archives/kent.pdf

5. Barge FH: "One Cause, One Cure." LaCrosse, WI. 1990.

(Dr. Christopher Kent, president of the Council on Chiropractic Practice, is a 1973 graduate of Palmer College of Chiropractic. The WCA's "Chiropractic Researcher of the Year" in 1994, and recipient of that honor from the ICA in 1991, he was also named ICA "Chiropractor of the Year" in 1998. He is director of research and a co‑founder of Chiropractic Leadership Alliance. With Dr. Patrick Gentempo, Jr., Dr. Kent produces a monthly audio series, "On Purpose," covering current events in science, politics and philosophy of vital interest to the practicing chiropractor. For subscription information call 800/892‑6463.)