Finally, I have come to say goodbye to you. As you probably know, there is a saying “Leave the best till last.” I am the greatest of all the organs and systems that have described themselves to you so far. I am an integrative system that forms a chain between every organ in your body. Just as your veins are spread out to carry nutrients and oxygen to every part of your body, I also embrace your entire system like a network, without leaving the tiniest space; I am informed of everything that goes on inside your body. Even if a tiny insect settles on your arm, you sense it immediately. I make you aware of a tiny drop of sweat on your body. I induce pain in suitable measures to inform you of any illnesses in your inner organs. In fact, I not only inform you, I also warn you to seek help.

However, it is hard for me to describe myself. When you hear the words “nervous system,” what comes to mind is a cluster of cells called neurons. But this is a great mass of cells, and we should always remember that we are referring to the most complex matter in all of creation. The very important main nervous systems, which are very close to one another, are the huge masses positioned beneath the skull, the extensions of my system and secondary nervous system; this latter is spread out through various regions of the body. It would take up too much of your time to describe each region and branch of my system individually to you each month, but in this way I could prove what a perfect and incredible duty each of them performs within your body. However, I will try to explain the subject briefly to avoid boring you. Nevertheless, please forgive me if I ramble on too much; we are describing the most excellent organ created by God so it is inevitable that there will be some complicated matters that need clarification.

Instead of allowing each of my sections to describe themselves to you individually, I will speak on their behalf as the “brain.” It may be easier for you to understand the system if we divide it into two. One of them is me and the nervous system which I lead; we can briefly describe this as the thalamus, hypothalamus, cerebellum, the medulla, and the spine. The other part is the peripheral nervous system, which emerges from the central nervous system and is distributed, rather like fiber optic telephone cables, throughout the entire body. In addition to me, the brain, and my two large cerebral hemispheres, there is another smaller section, which is known as the brain stem. The brain and its cerebral hemispheres and the sections of the brain stem which are protected beneath the skull (the cerebellum, medulla, thalamus, and hypothalamus) are very important. The spinal cord, which is also a part of the central nervous system, however is not in the skull, but positioned within the vertebrae that constitute the spine. Due to its connection with the central nervous system, any damage to the spinal cord can endanger life.

Although damage to regions of the body where the nerves are distributed from the central nervous system may cause paralysis, or functional disorder for the specific organ, such an incident is not life threatening.

If you recall, when the heart and circulation system described themselves they boasted – indeed the veins also seemed to brag a bit when they stated that they measured 75,000 miles (long enough to go around the world almost three times). But the nerves are approximately 477,000 miles, long enough to stretch from the earth to the moon, and back again… the nerves which are distributed throughout the various parts of your body measure 250,000 miles, and the total length of the central nervous system is 228,000 miles. Almost 200,000 signals pass through just one cell at a time, which means that every moment thousands of signals pass through millions of my cells all throughout your body, and flow from the central nervous system to the whole body and then back to the central nervous system. There are about 30 billion cells in my system. 10 billion of these cells are in the cortex, 10 billion in the cerebellum, and the remainder forms the structure of the nerves and other sections. As a comparison, a fly’s brain contains 100 thousand cells, and a rat’s brain has 10 million cells. The total number of connections and contact points (synapses) that my 30 billion cells use to send and receive signals is 100 trillion. The number of combinations that these connections can establish to send signals to one another is greater than the number of atoms in the universe. At the beginning of a thinking process, the number of cells activated is between 10 and 100 million, and according to the depth and intensity of the activity, these figures can increase to astounding numbers. Every second 4 billion signals are exchanged between the left and right hemispheres. When you were an embryo, just a few weeks old, I consisted of 92% water. When you were first born, the ratio of water was 90%. And when you were fully developed, the water ratio remains at 77%. Peter! Can you imagine, a heap of mass consisting of 77% water, the remainder made up of various element. Our Lord, the bearer of eternal power places me in you, in the head of the most honorable creation, and with me you form civilizations; you invent and discover. And even more important, with my mediation you have the ability to contemplate and reach your Creator. What we are learning about here is how with me you are able to recognize the wisdom of the entire universe. The electric signals of the various sense organs, such as the eyes, ears, nose, tongue and skin, all of which have previously described themselves, are transmitted by the receptive cells on various wavelengths; these are then conveyed to you in the form of sight, noise, smell and taste. In fact I am inducing you to write these words at this very moment. The evaluation of everything you do passes through me, but you are not even aware of it. When you walk, eat, talk, speak or sleep, the information I receive from every part of your body is reviewed and responded to in a suitable manner. Dear Peter! Could a single nucleus of a single one of my cells possibly position itself alone?

The Lord has created me so magnificently that you are still only aware of a very few of my mysteries. Each of the sections that I mentioned above has a distinct and important vital function. On their behalf, I will briefly explain their duties: The cerebellum is the nerve center from which the harmony of balance and muscle movement is controlled. As this section of me has no sense of perception, it is impossible to voluntarily change the functions of this region. The pyramid shaped medulla oblongata, which connects the spinal cord to the midbrain and the pons; the latter constitutes the other end of the brainstem through a hole in the back of the skull in the form of the spinal cord and enters into the vertebral column. Here, there are many nerve centers which regulate autonomic nervous system activity, such as the heart rate, breathing, and digestion process. This is also the center from which the reflexes are controlled, the body’s inner environment is regulated, and this center, working with the cerebellum also controls movement and coordinates signals received from the nerves of inner organs. Moreover, activities such as excitement and sleep are also controlled here in collaboration with the thalamus.

The thalamus lies between the brainstem and the hemispheres of the brain, performing a function rather like a junction or relay station. This section gathers all the signals sent by the sense receptors, except for those from the olfactory (smell) receptors, and conveys these signals to the cortex reflecting the information; there is also a role played in consciously identifying sensations such as pain, touch and noise. There is also a role played in the sensory changes that occur with the perception of senses in our consciousness and awareness, as well as in the regulation of sleep and paying attention. The hypothalamus, which is located below the thalamus, is an important center that controls sexual senses; the sensations of pain, pleasure, hunger, and thirst, as well as blood pressure, temperature and other functions of the inner organs. It also performs the important duty of regulating hormone release. The nerve fibers that enter this center, which is the location of a very complex network of nerves coming from the olfactory bulb, thalamus, and the frontal lobe, reach the autonomic nervous system, the reticular formation in the stem section, and the posterior lobe behind the pituitary gland (hypophysis). The pituitary gland, one of the most important systems that earlier described itself in the endocrine system, produces hormones that stimulate secretion in the anterior section, as well as the oxytocin and antidiuretic hormones which are stored and released from the posterior pituitary.

On the base of the deep grove that separates the two hemispheres of the large brain there is a callus-like body; this is a bundle of axon (nerves) called the corpus callosum which connects the two hemispheres. Because the nerve fibers cross and change direction in the medulla, the left side of the brain controls your right side, and the right controls your left. Although my two hemispheres may look like a reflection of one another, there are some variations in their duties; for example, the left hemisphere controls speech, but the section which controls the perception of location is in the right hemisphere. Whilst you use the left hemisphere for duties that must be performed in a specific order (activities such as adding and subtracting or buttoning a shirt), you use the right hemisphere in thinking with images (for example, mapping the route from your home to the market). If the callus substance that connects my two hemispheres did not exist, there would be no communication between the two, therefore, you could read the word “fish,” but you would not be able to picture the image of a fish in your mind without the right hemisphere to achieve this.

The brain, the grey-colored mass of folds and grooves that covers the top of my anatomic hemispheres, the region where the main stems of my cells are found, is called the cortex or grey matter; the lighter colored matter that lies beneath this, the region where the axons (stems of neurons) are found, is called the white matter. My cortex region, which is composed of six layers of cells, is the center where the sensory signals are received and analyzed and where voluntary muscle movement is controlled, while also being the center of activities, such as learning, reasoning, and remembering. My two hemispheres, the focal point of conscious activity and thought that forms the large brain, constitute 85% of the whole brain. When you were first born I weighed 400 grams, but I grew very quickly, and by the time you were a year old I weighed 800 grams. When you were four years old, I weighed 1,200 gr. However, my growth began to slow down after the age of seven, and when you reach twenty, I will weigh approximately 1,379–1,434 grams. When you begin to pass your first youth, my weight begins to decrease every year by 1 gram, so when you reach seventy-five, I would have shrunk in comparison to when you were twenty. The reason for this decrease in weight is that approximate 50,000 neurons die, or cease to function daily, after you reach the age of twenty. The body cells of the cartilage, bone, skin, ligaments and the liver divide, regenerate and increase in number; however, the nerve cells that are part of me continue to increase until they reach the figure set out for you when you were formed in your mother’s womb; they then lose the ability to segregate. So if there is any damage, relative functions fail because the cells in that region have died. Then the question arises: As there is no increase in the numbers of cells, how does the weight continue to increase until the age of twenty? Well, there is not an increase in the numbers of cells; rather, there is an increase in the number and growth of connections between the cells and this is how my weight increases. Of course, nutrients are added to build and stimulate these connections. Subsequently, with age these connections begin to decrease. With ever experience you have, all the things that you learn or see during your youth these connections increase, and in turn this increases my capacity for thought and reasoning. If you continue to activate your brain by reading, writing and other social activities in old age, these connections continue to increase. Even if there is a decrease in my cells, you are able to continue your usual activities without losing any functions of the brain. But as soon as you say that is enough, it is time for a rest, my cells begin to withdraw their connections immediately, and in time you will certainly see the difference in my capacity. If the cells in my central nervous system are injured or damaged, they cannot repair themselves. However, if the cell bodies of my cells in the peripheral nervous system are not damaged the stems are repairable.

Thanks to this special feature if a severed arm, leg or finger can be carefully replaced with microsurgery, the nerves can repair themselves, and the limb will continue its normal functions. The visible cause of this characteristic is found in the nerves of the arms and legs, but not in the brain or spine, is the casing that surrounds this bundle of nerves that transmits signals for the cells to grow. Even with the greatest of techniques, no surgeon could sew the severed nerve fibers. However, thanks to the nerve casing that holds these fibers together (like the plastic that covers the electric cable, consisting of thin wires) the severed limb can be replanted. Then with guidance from this outer casing, each of the hundreds of fibers found inside grow 1 mm every day, and in a period of between 1 month and a year, they will begin to function again.

Irfan Yilmaz is a professor of biology at Dokuz Eylul University, Izmir. 

Programs and documents on the computer are held in two areas: software and hardware. For scientists, one of many goals is to make the processors or chips, which are like the human brain that consists of nerves, much smaller, but still powerful enough to process many more calculations. There are many differences between the current chips and earlier ones. Chips which will be produced in the future will be smaller and probably process more calculations more quickly.

Programs, which can be seen as being the mechanical counterpart of the human mind, bring the above-mentioned improvements into daily life. New programs boost the capability of the computer in parallel with the capability of their chips. Without these programs, computers would be no more than ordinary electronic machines.

Developed technologies in fields like industry, communication, or the military bring us face to face with new developments and have made the computer an undeniable part of our lives. Mobile phones equipped with new features, medical machines which can easily make a large number of analyses and provide ease in diagnosis and treatment, robots that can operate with minimum error and have a low cost when used in production, and weapons that automatically focus on the target are all part of this progress.

With time, software and hi-tech sensors have enabled computers to communicate with people; there are now systems that are controlled by the voice, which are able to recognize a person from their iris or fingerprints, control systems which are carried out by touching a screen, etc. Such systems are operated with the help of special sensors or by some signals that carry messages from the person or the environment to the computer. The most important feature of these sensors is that the signals produced at the output are very weak and there are few differences between them. An ATM can recognize a particular person’s iris, thanks to the ability of its computer to compare the signals from the ATM’s iris scanner with previously recorded data. In this process, the computer uses the small differences that one person’s iris has to another’s. In this or similar systems, complicated programs are used, called “expert systems” or “artificial intelligence”. These programs imitate human senses, but they aim to operate with an even keener sensitivity and clearer criteria.

A question that is a subject of fiction comes to mind; “Will computers vie with or even fight with human beings?” In the mid-term, the rapid development of technology will create computers which can communicate with humans, which can understand them, and put forward ideas. A negative outcome of such a situation depends, once again, on man. Such a horrific situation could be the result of technology that can cause environmental disasters; this technology is almost identical to the one that we have described above. If we are able to establish an understanding of “civilization” which does not ignore human values for the sake of technological development, then such fears will be groundless.

Artificial Nervous Systems

As we all know, people have imitated nature in many of their inventions. In a way, artificial nervous systems imitate how a nerve cell learns and how it works. Fuzzy systems however imitate how the judgment of a human being works, rather than the nerve cells of the brain. In these systems people try to form a decision making criterion by assuming that there are endless grey tones between white and black or by assuming that there are infinite values between zero and one.

The purpose of the research on artificial nervous systems is to understand how the brain operates, then to make a system that imitates it and carries out the same operations. Artificial nervous systems are made of simple nerve cells which are bound in parallel, called process elements; these allow for real objects to be seen as if they were biological systems.

Here, the program that resembles the nerve cell operates in the same way as a nerve cell. The main part of a nerve cell is formed from the body, called a “soma”, an “axon” that is bound to the body and many “dendrites”. There are many “roots”, or synapses, on the dendrite of a cell which make contact with the dendrites of other cells. A nerve cell either transmits the electrical stimulus that comes through the axon to the other nerve cells through the synapse, or it does not transmit it, depending on whether or not the signal is over or below the threshold value. So a nerve works by itself, but its activity becomes meaningful when working as a part of a nervous system. It would be useful if we consider how the learning process occurs here. It is thought that the required data are stored in the memory center and this fact is taken as a model for some artificial nervous system software that has been successfully developed to date.

A nerve cell and the process of transporting signals from one cell to another can be written as software. It is clear that a natural nerve cell is more complex and that it is bound to more cells than an artificial one can be. The number of communication ports (synapses) of a natural nerve can vary from between 1,000 to 10,000.

An artificial cell produces output if the input value is over the cell’s threshold value; if this is not the case then there is no production. If there is output – as in natural cells – then this output is transported to the next cell group. Each cell produces its output as an input for the next cell.

A cell is separated into three groups: input, the hidden layer and output. Each group is considered to be made up of one layer, while the hidden layer can consist of more than one, according to the complexity of the job. As can be seen, the placement of the layers is similar in the process of the human body. We can compare the cells on the input layer with human senses. In this way we can teach a robot to avoid heat and cold, we can make them see and act according to this information. (Do not forget that a robot is in fact a computer.) It is natural that some sensors must be bound to the cells on the input layer. For instance, a sensor which is sensitive to heat can make the robot react to heat when the temperature is over the limit value or when the temperature is dramatically low it can move closer to a heat source. Or if pictures received from a video-camera are similar to an object that has been fed into the robot such data input can cause the robot to move to that object.

Artificial nervous systems are not only used in robot applications. They are commonly used in making clinical diagnoses, determining market-customer profiles, recognizing voices or pictures, classifications such as determining micro-structures, like germs and cell materials, economic profiles, energy sources, the futures of market shares, some predictive sciences, such as weather forecast, zipping data for computers, process control in industry, checking resources and some other matters in technological areas. As can be seen, there are many application areas for artificial nervous systems, all of which differ from one another.

The Basic Features of Artificial Nervous Systems

The features of artificial nervous systems can be simplified as follows: firstly, they can learn how to solve problems. In order to do this they use sample data and learning styles and while doing this they do not require any special help. Secondly, they can recognize important features and relations to help them distinguish different data forms.

When an artificial nervous system is operated, the first thing to be carried out is the training process. In order to do this, the program needs to have two alternating operations. It may obtain information concerning some results to be achieved, using results that come from the user, or the program is itself asked to produce some results. These two types of learning are not very different from how a human learns. One shows a young child an animal, and repeats the name. Now the child has learned the name of the animal and correlates it with the picture of the same. If no one teaches a child what a bird is, the child will all the same classify all animals that have wings and beaks and that have a certain physical shape, maybe even creating a name for the animal by him/herself. The difference between the computer and the human in this process is that a human has the ability to judge, while computers classify the animals according to their shapes and groups them thus. Naming and giving a naming feature to the computer is again a decision that a human will make. When the training process is finished, the data can be entered into the computer and the desired results can be attained.

Artificial nervous systems are changing and developing day by day. With each new development they become closer to the human nervous system; they are able to recognize different characteristics of different people and they are learning to make sorting decisions, even limited judgments. Whether or not these machines may one day enact a nightmare scenario, taking over from us is not a great threat, as whatever they are capable of doing is up to us to decide, as their “masters”. We should not fear these systems, but try to develop more of them; such systems help us in every day tasks, from drawing money out of the bank to our annual check-up at the doctor’s.