A Divide Mind Can Stand United

Unlike nations and houses, your mind apparently can stand strong while divided.  The individual parts work largely independent of each other for the majority of tasks. The unification of the human mind is actually an illusion.

Put very simply, the human brain is divided into two hemispheres that are largely symmetrical. Both hemispheres process sensory information and controls the motor functions from one half the human body. The left brain hemisphere gets the right side of the body’s sensory input and vis versa.  The left hemisphere is more dominate with speech and language, doing more of the heavy lifting in that area, while the right side focuses on nonverbal information.

For the average person, these two separate hemispheres operate in parallel just fine. This reinforces the “one mind” feeling that most of us have. But this breaks down once something happens to your brain. For example, when you have a stroke:

Mrs. Blanford was suffering a stroke. An interesting thing happened when I brought her left arm up across her face so she could see it. I asked, as I always ask such patients, “Whose arm is this?”

“That is your arm.”

“Then why am I wearing your ring?” I pointed to her wedding band.

“That wedding band belongs on the arm of Mrs. Blanford.”

“So whose arm is this?”

“That is your arm.”

Patients like Mrs. Blanford sometimes accuse me of stealing their rings or watches. Even if we demonstrate that their arm is attached to their body, they are never convinced the arm actually belongs to them. At most, one is able to render them briefly confused, and then the condition reestablishes itself. The condition is called “neglect.” There is nothing extraordinary here. Mrs. Blanford’s case is not rare. There are countless cases of left-side neglect due to right-brain strokes.

What is happening in this example is that the right hemisphere is dysfunctional, unable to process anything from the left side of her world. By default, it is not the left hemisphere’s job to recognize the left side of the body, and the left hemisphere can’t immediately step in to do that task. To the left brain, the left side of the body essentially does not exist. The right brain has failed, not only to process arm information, but failed to let the left hemisphere know it failed.

This can be a scary thought to consider: that you might not know your own body. But there are greater implications than this. Your physical actions are not the only thing dominated by your brain. Your entire personality, habits, speech pattern, etc are all created by the interplay of the two hemispheres of your brain.

Should one hemisphere completely stop functioning, your personality can shift in unpredictable ways. This is especially true when it is the left hemisphere is damaged. Because it controls the primary language functions, the patients ability to communicate is severely hindered. The ability to do simple things like identify common objects will hindered, let alone form complex and abstract thoughts. You can see signs if this in victims of split-brain.

The concept of a unified brain feels very intuitive to us. But the science shows that we are actually very much the sum of our parts. Makings you think.

-That is all.