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Thursday, March 7, 2013

How The Brain Works


Our brain is a collection of separate parts that must learn to work together. To help explain this, neuro-physiologist, Dr. Paul Maclean, who headed the federal government laboratory of brain evolution, has developed the concept of an evolutionary "triune" brain structure in his revolutionary book, "The Triune Brain in Evolution."

At the top of the spine we have a brain stem. At one time in evolution of vertebrates this was all the brain the organism had. It is often called the reptilian brain. Most of our automatic and instinctual responses (fight or flee, etc.) come from the reptilian brain.

Also found on the back side of the brain stem is the cerebellum, a very old part of the brain from an evolutionary point of view, that is responsible for the subconscious coordination of all muscle movements.

On top of the brain stem, deep within the cerebral cortex, is found the next step in evolution, the primitive mammalian brain, often identified as the limbic lobes. The mammalian brain is found in all mammals including the most primitive mammal. This is the seat of our emotional responses.

As mammals became more highly evolved, they developed a cerebral cortex surrounding the mammalian brain. This is where our logical thinking is, voluntary muscle control, centers for vision and other senses.

When you look at a frontal view of the brain, it looks like a giant walnut. The brain has a deep notch running from front to back. It looks like half a shelled walnut. Thus in the cerebral cortex we have what are called left and right brain hemispheres.

The neurons running between the body and the brain cross over in the medulla (a part of the brain stem) so the left hemisphere is associated with the right side of the body and the right hemisphere with the left. Between the two hemispheres we have a narrow communication bridge that we call a corpus callosum.

We need to communicate between these two halves for many activities. The left hemisphere we can call the linear logic language hemisphere. The right hemisphere is the visual and integrating hemisphere. The left-hemisphere is reductionist and sees our world as little bits and pieces, and the right hemisphere sees the big picture. Western culture is primarily left-brained, and eastern culture is primarily right brained