No two minds think alike

Earlier this month, the federal government began implementing long-overdue spending cuts. At the same time, President Obama announced plans to dedicate $100 million for another “big science” political project–a new neuroscience initiative called the Brain Activity Map. Set to launch next year, the Obama administration says it hopes the new research will lead to advances in the treatment of Alzheimer’s disease, epilepsy, and traumatic brain injuries.

I’ve seen way too much political science in Washington to expect much return from this $100 million “investment” of taxpayer dollars for more of the same tired, old, high tech, and unnatural approaches. And I don’t have a lot of faith that it will lead to any major breakthroughs in how we treat brain diseases and injuries.

Especially when you hear the names of the government agencies involved in the initiative. The Office of Science and Technology Policy will run the initiative. And the National Institutes of Health, the Defense Advanced Research Projects Agency, and the National Science Foundation will also participate.

Plus, this project sounds all too familiar. During the 1990s, there was big political fanfare over the so-called “Decade of the Brain.” So I guess we can call this “Decade Two”?

The good news is, we already know a lot about the human brain. Starting with the fact that, anatomically, there are actually multiple brains.

The cerebellum–the “little brain”–sits at the back of the brain, on top of the brainstem. It is responsible for balance, coordination, and fine motor movements.

The cerebrum–or the “big brain”–is much larger. It sits on top and to front of the brain. It does most of the brain’s “thinking.” (Or as Quick Draw McGraw would say, “I’ll do the thinnin’ around here.”)

The cerebrum itself is made up of two brains. The right half and the left half–or right and left hemispheres.

Because the nerve fibers crossover from side to side as they travel between the body and the brain, the right hemisphere connects to the left side of the body. And the left hemisphere connects to the right side of the body.

This is true, except when it comes to the nose. Olfactory nerves travel directly from the nose into the frontal lobe. So odors in the left nostril are processed in left hemisphere. Likewise, odors in the right nostril are processed in the right hemisphere.

But if you suffer a stroke that damages the right side of your brain, the left side of your body will not respond to stimuli. Likewise, if the stroke cuts off blood to the left side, the right side of the body is affected.

The left side of the brain is cheerful and positive. But it’s also prone to self-deception. It can make up reasons for far- fetched actions.

The right brain, on the other hand, sees the world as a dangerous place. When not moderated by the left, the right brain tends to sadness. Perhaps because it sees the world more accurately without self-deception. You can have anxiety and sleep problems with over-activity on the right side of the brain.

The left brain thinks in a linear and sequential manner. It evaluates parts of the whole, in a reductionist manner. And it’s extremely literal.

If asked to interpret the statement “a rolling stone gathers no moss,” the left brain would start talking about stones or pebbles on a hillside. And the effects of gravity. And what kinds of surfaces different plants can grow on.

You might say our modern biomedical research paradigm is built using the left brain. While “holistic” approaches use the right brain.

The left brain also excels at linear mathematics, such as arithmetic and algebra. It recognizes geometric forms. But it can’t visualize, manipulate or copy them.

Over on the right, the brain is intuitive, creative, and holistic. It can simultaneously grasp the whole of an idea without need for dissecting the parts. It performs spatial math, such as geometry and calculus. And it can estimate with remarkable accuracy, without conducting detailed calculations. It can also manipulate and reproduce geometric forms.

Hopefully, you are beginning to see the pattern.

Many people don’t realize the left brain is also responsible for complex verbal ability. It helps us with abstract verbal concepts in our native–or first–language. The left side also interprets alphabet-based writing such as English, Chinese kana or Japanese hiragana, and cursive writing. These are all analytical tasks.

During waking hours, the talkative left dominates the relatively silent right brain. The left brain also creates long-term memory and verbal memory. But it does not contribute much to athletic ability.

Trained musicians use the left side of their brains. They analyze and interpret chords, notes, and rhythms on the left side. Untrained listeners process music on the right side, however.

Marijuana depresses left brain activity. Therefore, it depresses verbal ability. It can also lead to over-activity in your right side. This is why some people on marijuana experience anxiety.

We also see that in abused children left side activity of the brain can become depressed. The left side can even shrink in size in abused children.

Now, back to the right side…

The intuitive right side creates short-term and visual memory. It holds images and dreams that fade within seconds. Its verbal ability is poor. So that’s why dreams–when you remember them–have so little talking.

But the right side can sing, recite poetry, and swear. It “speaks” through images, dreams, and physical actions. Foreign languages learned during adulthood are processed here on this side, via tone and rhythm.

The right side reads printed words and pictographs, such as Chinese characters. It handles visual clues, facial recognition, expressions, body language and social contexts, as well as shades of color.

The right side is also responsible for complex athletic ability.

The right scans both sides of space, shifting attention as appropriate. It also recognizes melody, rhythm, and memorization. So when you play a piano piece by ear, you use your right side. You recognize auditory patterns and your “fingers know the piece.”

Damage to the right side may cause hyperactivity, poor focus, and inattention to stimuli coming from the left side of body.

Drinking alcohol depresses the right side more quickly and to a greater extent than the left. So, a drunk may be able to speak coherently, but fail to recognize a stop sign. Or fail to read social cues accurately. And they certainly lose athletic ability with the more they drink.

We really need both sides of the brain to function normally. And they are connected to communicate with each other through the fibers of the corpus callosum.

The corpus callosum may be absent at birth. And it’s even been surgically transected to control epileptic seizures. In these cases, individuals are still able to lead a somewhat “normal” life. But, they do experience problems. For example, the right hand–controlled by the left brain–will be unable to write a coherent sentence. And the left hand–controlled by the right brain–will be unable to draw a simple three-dimensional figure.

Studies also show that Alzheimer’s disease patients suffer progressive atrophy–or wasting away–of their corpus collosums. And without a functioning corpus collosum, the two sides of the brain can’t communicate with each other.

So, the next time you or someone else says, “I am of two minds” about something, you should realize that you are describing an anatomical and physiological reality about the human brain.  And not just assessing different sides of an issue.

In my consulting medical practice, the facts and analyses often lend to saying, “on the one hand, this; on the other hand, that.” Then, like a lot of medicine, it comes down to weighing the probabilities.

Here’s hoping that my pessimistic view of President Obama’s Brain Mapping Project is just my overactive right brain. He seems to be thinking with his left.



2. Arch Neurol. 2002 Feb;59(2):243-8.