Cerebral hemispheres of the brain

Cerebral Hemispheres

How many brains do you have - one or two? Actually, this is quite easy to answer...you have only one brain. However, the cerebral hemispheres are divided right down the middle into a right hemisphere and a left hemisphere. Each hemisphere appears to be specialized for some behaviors. The hemispheres communicate with each other through a thick band of 200-250 million nerve fibers called the corpus callosum. (A smaller band of nerve fibers called the anterior commissure also connects parts of the cerebral hemispheres.)

Handedness

Are you right-handed or left-handed? As you probably know, most people (about 90% of the population) are right-handed - they prefer to use their right hand to write, eat and throw a ball. Another way to refer to people who use their right hand is to say that they are dominant. It follows that most of the other 10% of the population is left-handed or "left hand dominant." There are few people who use each hand equally; they are "ambidextrous." (Most people also have a dominant eye and dominant ear...test your "sidedness" here.)

Exactly why people are right-handed or left-handed is somewhat of a mystery. Dr. William Calvin has developed a fascinating theory about the origin of handedness and has written an essay called The Throwing Madonna to explain it.

Right Side - Left Side

The right side of the brain controls muscles on the left side of the body and the left side of the brain controls muscles on the right side of the body. Also, in general, sensory information from the left side of the body crosses over to the right side of the brain and information from the right side of the body crosses over to the left side of the brain. Therefore, damage to one side of the brain will affect the opposite side of the body.

In 95% of right-handers, the left side of the brain is dominant for language. Even in 60-70% of left-handers, the left side of brain is used for language. Back in the 1860s and 1870s, two neurologists (Paul Broca and Karl Wernicke) observed that people who had damage to a particular area on the left side of the brain had speech and language problems. People with damage to these areas on the right side usually did not have any language problems. The two language areas of the brain that are important for language now bear their names: Broca's area and Wernicke's area.

Images courtesy of Slice of Life.

Cerebral Dominance

Each hemisphere of the brain is dominant for other behaviors. For example, it appears that the right brain is dominant for spatial abilities, face recognition, visual imagery and music. The left brain may be more dominant for calculations, math and logical abilities. Of course, these are generalizations and in normal people, the two hemispheres work together, are connected, and share information through the corpus callosum. Much of what we know about the right and left hemispheres comes from studies in people who have had the corpus callosum split - this surgical operation isolates most of the right hemisphere from the left hemisphere. This type of surgery is performed in patients suffering from epilepsy. The corpus callosum is cut to prevent the spread of the "epileptic seizure" from one hemisphere to the other.

Dominant Functions

You might also like

ALCOHOL FACTS and Effects on the Human Body (1949
ALCOHOL FACTS and Effects on the Human Body (1949 ...
Development of the Declarative Memory System in the Human
Development of the Declarative Memory System in the Human ...
Top Ten Myths About the Brain
Top Ten Myths About the Brain
7 Incredible Things Your Brain Didnt Know About Your Brain
7 Incredible Things Your Brain Didnt Know About Your Brain
10 Amazing Facts about the Human Body
10 Amazing Facts about the Human Body
7 FACTS ABOUT HUMAN BRAIN
7 FACTS ABOUT HUMAN BRAIN

Q&A

avatar
What is an Interesting fact about the power of the human brain?

Although the brain accounts for less than 2% of a person's weight, it consumes 20% of the body's energy. !

Copyright © . All Rights Reserved