Chapter 5: The Human Brain

Overview

Before we go any further we shall look into some of the basics of how the human brain functions.

Your brain is made up of something like 10 “1000 billion neurons or nerve cells. Most of these cells develop at an early stage in life.

Each of these cells is capable of developing thousands of synapses, which are the connections to other cells in the brain. The more of these synapses you have, the more connections you are able to make. The early experiences in your life determine how well those connections will function and how many you are able to make.

The organism with the highest number of connections produces the most complex, ˜ intelligent behaviour. A low number of connections gives only a low number of possible reactions .

Those parts of the human body that perform the most complex movements demand a relatively higher portion of neurons in the brain. A hand, for example, is served by a larger number of neurons than a foot .

The human ability to speak is inherited, which is shown in the brain by the larger number of neurons that serve the mouth, the tongue and the larynx, compared with monkeys or other close relatives. The brain coordinates impulses from our senses to produce the appropriate behaviour.

The fact that the brain has two sides is not new, but the research that has been done mainly since the 1960s has led to some interesting discoveries.

The American Roger Sperry, who was later awarded the Nobel Prize in Medicine, led that research. He started a number of experiments on monkeys, which had their corpus callosum (the band of some 300 million nerve cell fibres connecting the two cerebral hemispheres) cut off. He found the monkeys could still behave in an apparently normal way and they could still learn new things. What he discovered was that the two hemispheres of the monkey brain seemed to live their own lives without knowing what the other half was doing.

Sperry then heard about similar operations on human beings with severe epilepsy. They also functioned in a normal way after the operation without any consequences on their memory learning abilities . In cooperation with these split-brain patients he then performed a number of interesting experiments.

It was already known that the ability to speak is a left hemisphere activity. Could the patients then talk about something that only the right hemisphere had ˜seen ? As the left hemisphere directs the activities of the right half of the body and the right hemisphere directs the left half of the body, the experiments were arranged so that a picture could only be seen by one eye. When the patient was asked to tell what he had seen he could only name the pictures he had seen with his right eye. However, he could use his left hand to pick out the objects he had seen with his left eye.

The right hemisphere is ˜mute , but is very skilled at distinguishing colours and forms. The right hemisphere also seems to be more skilled at distinguishing dimensions, patterns and wholeness, while the left hemisphere is more verbal and handles information in a sequential, logical way.

As a simplification, one could say that the left hemisphere can t see the forest because of the trees, while the right hemisphere can see the forest but not the trees. This means that each hemisphere is susceptible to different types of impulse. Logical, structured language is more suitable to the left hemisphere,

while associations, pictures and analogies , the language of poetry and myths, is the kind of language that suits the right hemisphere. These two types of language also give different descriptions of reality, where intellect is opposed to intuition and feelings.

In western societies ˜left-brain skills are highly appreciated. During the last five to ten years we have become aware of the imbalance and its consequences. We have begun to value creativity in people more and to train people in whole-brain skills. We know from schools which put a lot of emphasis on art, music, literature and other creative skills that the students perform a lot better also in mathematics, languages and other ˜left- brain skills .