Understanding the Brain

Understanding human brain

Rakesh Mohan Hallen

Believe it or not, the biggest challenge to the best brains in the world today is to understand and emulate the brain. It is the center of perception whether of the universe or the self. No wonder we strive to understand it. Our efforts have yielded some results. How far we understand it today is reflected in the following queries.

The Organ

* What is brain?

* How does our brain control the entire body?

* What is the weight of a human brain?

* How does the human brain function?

* How does a neuron work in the nervous system, electrically or chemically?

* It is said that a fold in the upper surface of human brain is the seat of wisdom of the person. Is it true?

* What is the difference between the brain of an ape and a human brain?

* Why are some people more intelligent than others?

* What is the difference between human brain and a computer?

* What is the difference between mind and brain?

Brain is the master control organ in a living organism. Although, most invertebrates (animals without a backbone) do not have a well-developed brain, they do have clusters of nerve cells, called ganglia, that coordinate the activities of their body. On the other hand, all vertebrates (animals with a backbone) have some kind of brain. The function of a brain is to receive information from the sensory organs and nerves, about conditions both inside the body and outside it, rapidly analyze this information and then send out messages that control the various functions and actions of the body. The brain also stores information from past experience, which makes learning and remembering possible. In addition, the brain is the source of thoughts, moods, and emotions.

The human brain is a grayish-pink, jelly-like structure with many ridges and grooves on its surface. It is largely made up of several billion neurons (nerve cells). These neurons contribute to the mental activity, by firing electric impulses. The firing of nerve impulses depend on changes in permeability of the membranes of nerve cells to inorganic ions, in particular sodium and potassium. These changes are brought about either by electrical stimulation, or by specific chemical transmitters ( e.g. acetylcholine) released from the nerve endings at the synaptic junctions (synapse). Thus each neuron can communicate with its near or distant neighbors. Neurons have branches, like trees. As a nerve cell branches out, it allows for more subtle connections with other far away neurons, not just the nearby ones that do similar things.

Although the brain makes up only about 2 per cent of the total body weight, it uses about 20 per cent of the oxygen used by the entire human body when at rest.. A newborn baby's brain weighs less than 0.5 kilogram. By the time a child is 6 years old, the brain has reached its full weight of about 1.4 kilograms. However this increase in weight is not due to addition of more nerve cells. Most of the brain's nerve cells are present at birth. The increase in weight comes from growth of nerve cells, development and growth of supporting cells, and development of connections among cells. During this six-year period, a person learns and acquires new behaviour patterns at the fastest rate in life.

We are yet to know many intricacies of the human brain. Yet scientists believe that we now understand the basic functions fairly well. Millions of lines of communication in the neural network connect one region of the brain with another, and these in turn to the other parts of the body. Thus the brain is in communication with all the vital organs of the body -- the lungs, the kidneys; the heart and other organs. It gets information from various specialized cells (receptors) about the sensations of touch, heat, cold, taste, smell, vision and hearing and controls the muscles to produce action. However, every act of the human body is not a direct result of the electrical impulses of the neurons alone, some actions are also controlled by the secretion of some chemicals into the blood. For example, a particular part of the brain, known as the pituitary gland is responsible for many such secretions. Similarly some actions of the body known as the involuntary reflex actions, like the pulling back of our hand on accidentally touching a hot object, are mediated not by the brain but by the spinal cord. This is so because of the fact that the time necessary for a nerve impulse to travel to the brain is a trifle bit more than to the spinal cord.

The mechanism of learning and analysis are still an enigma. When the brain receives a totally novel signal from any of its sensory receptors, like when we taste something totally new; or we get an electric shock for the first time, somewhere in the middle of the head a diffuse foliage of nerve cells and tendrils pick up from stream of incoming messages a series of hints that something has happened. This information, crude, unspecific but emphatic, is broadcast to many distant regions. The effect is to alert the whole brain. When the situation is novel and the intensity of signals is high, the widespread responses are almost in the nature of an alarm. But familiarity breeds indifference, the brain learns to assess the message and file it away unless it is of some vital importance. Thus in the course of time, after many trials, the brain establishes the meaning and importance of new messages..

The brain has three main parts: the brainstem, the cerebellum and the cerebrum. Different parts of the cerebrum are involved in different functions. The left half, for example specializes in speech, language and numerical calculations; the right, in five senses and recognition of patterns. The most vital component of the human brain is the cereberal cortex. It is also known as the gray matter. It controls the functions of inquiry and foresight, of planning, initiative and creating of new ideas. Beginning as an insignificant segment of the brain tissue of a human embryo, this gray mantle eventually grows so large that it must fold in on itself in wrinkles to accommodate its expanding surface within the skull. In a way it is the seat of wisdom.

Intelligence can be defined as the ability to analyze and synthesize a complex situation using past experience. Although several scientists have tried to find out which features of a human brain may be linked