In our previous article where we discussed the mind-boggling complexity of our eyes’ retinas. We learned about the ten separate layers of cells, but we did not elaborate on the intricacies of their creation. We also learned how the substance in the cone cells, called rhodopsin, is destroyed on exposure to light and then regenerated in the dark. We thus touched on the wisdom behind the existence of both night and day.

The destruction of rhodopsin is caused by the generation of electricity after its contact with light. This electric impulse is transmitted from cones and rods to either horizontal or bipolar (having two poles) cells. The section between these two different layers of cells is called the outer plexiform layer, where horizontal cells receive electric impulses from rods and cones, and carry them to neighboring bipolar cells. The horizontal cells are also charged with transmitting electricity horizontally between rod and cone cells. The signals make it possible for shapes to be carried to the central nervous system in an appropriate contrast. Other signals are blocked so that the borders of the place of contact with light can be clarified in the brain, which does not receive an excessive load of signals. If it were not for these cells, it would be harder to perceive borders because the line of difference between two different colors would not become clear.

Bipolar cells have two opposite poles. They are created as one of two types, in accordance with their functions: one amplifies generated electric impulses, while the other inhibits the transmission of excessive impulses from around the perceived object to the brain. Bipolar cells provide the contrast necessary for making borders clear. They make clear vision possible, and yet most people have never heard of this wondrous gift inside their retinas!

How is contrast enabled?

Thanks to an innate ability, our brain does not occupy itself with regions that have the same color or the same light. It will not be stimulated much if, for example, a wall is completely white or a car is bright red all over. If, however, there are other colors on the wall, say, a white moon or star on a red background, then there will be more stimulation in the brain. Suppose we place the shape of a crescent on the wall. The stimulated parts of the brain will lie along the sharp ends of the crescent, not in the inside or outside of it. The stimulation in the brain is less associated with non-contrasting regions than contrasts in view. The higher the contrast, i.e. the greater the difference between light and dark areas, the greater the degree of stimulation.

Amacrine cells in the inner plexiform layer of the retina enable horizontal transmission. There are up to 30 different types of these cells, and they carry out at least five to six functions. For instance, one type of Amacrine cell transmits electric impulses from cones and rods to bipolar cells, then to other Amacrine cells, then to ganglion cells, and finally to the brain.

Another type of Amacrine cell responds strongly to the onset of the visual signal, while another to its completion. One other type reveals the difference in light intensity regardless of direction, while still others respond to the movement of a light point in a certain direction in the retina, causing a perception in the brain as to the direction of the light.

Further research may reveal yet more functions. Amacrine cells might have such functions as regulating the intensity of electric impulses specific to each wavelength and generating different levels of impulses for moving or stationary objects.

The function of the ganglion cells in the innermost layer of the retina is to help ensure that the electric impulse generated and corrected in the retina is eventually transmitted to the brain. Three distinct ganglion cells are identified in the retina. These cells are represented with the letters W, X, and Y. W cells are assigned the task of transmitting signals from rod cells, which produce black and white visual signals in the dark. Making up about 40 percent of all ganglion cells, they have diameters of less than 10 micrometers and transmit signals at a speed of 8 m/sec. It is evident that these cells are assigned the task of perceiving objects in the dark as rough, vague shapes.

X cells, on the other hand, transmit electric impulses to the brain, creating precise color pictures of objects. Making up 55 percent of ganglion cells, they have midsize diameters (10-15 micrometers) and transmit signals at a speed of 14 m/sec.

The largest of ganglion cells (with diameters as long as 35 micrometers), Y cells are assigned the task of transmitting instant changes in sight. Making up only 5 percent of ganglion cells, they send signals at speeds of 50 m/sec.

Sending intense signals in split seconds, Y cells inform the central nervous system immediately in case of a threat or an unusual encounter. When our body or eyes face a threat, these cells help protect us by warning the brain to move away from the threat or close our eyelids rapidly. If it were not for these cells, we would not be able to reflexively close our eyes and thus protect them. It’s incredible to ponder how complex these systems are – and how perfectly they’ve been created.

Between layers of cells there also lie layers of network that house neurons and their connections (synapses). These cells too have subgroups trained to carry out specific tasks. All of these cells are built according to certain specifications so that they can transmit stimuli to the brain when they receive light. Extremely severe visual problems develop when even a single layer of these types of cells is missing. Every one of the layers in our eyes is immensely special, and it is hard to imagine them to have been randomly placed there. It should be born in mind that this article simply skipped numerous elements of the retina and their chemical functions. Taking the precise measurements and mechanisms into account, we can only feel greater awe and love in the face of the incredible art devoted to the creation.

The first article can be found at https://fountainmagazine.com/2018/issue-126-november-december-2018/retina-the-mind-boggler

The dispersal of scent takes place via the thermal and light-like behavior of the fragrant particles in the air. Thousands of points, letters, and words are positioned in each and every air particle. Each molecule is created in a form to carry sounds, sights, and odor. Millions of sound waves, scents and images are being transported and translocated into each of the trillions of air particles without deforming or mixing. As our knowledge pertaining to this transport grows, new technological products that will enable the transport of odors will be offered to the service of mankind.

Our sense of smell occurs in the brain. The chemical molecules exiting a lemon peel stimulate the odor receptors in the nose, which are then transmitted to brain to be interpreted as electric signals. Our olfactory system can easily distinguish more than ten thousand scents. This has inspired scientists to design similar devices. These models are called “electronic noses.”

A series of chemical receptors are utilized in the electronic nose instead of the receptor proteins of the human nose. Each of these is designed to sense various scents. These devices are difficult to produce, as the cost grows for a more sensitive device. The signals that sensors collect from the environment are converted into binary codes via electronic systems and then sent to a computer. The role of human nerve cells in charge of sensing odor is replaced by the electronic systems of a computer.

Mostly in their early phases, electronic noses are beginning to be used in various sectors, primarily those involving foods and perfumes, as well as the medical and chemical industries.

How does odor transportation take place?

As I already mentioned, the aromatic molecules transported via air particles in their gaseous state are detected by the smell sensor system and converted into electric signals. Quite a few different materials are used as conductors: conductive polymers, semi-conductive metal oxides, a quartz-crystal micro-balance (QMB), surface acoustic wave (SAW) sensors, pellistors, and infrared sensors.

Once the electric signals are converted into binary, the odor information is determined via a software program in which algorithms such as artificial nerve networks and support vector machines are employed. This information is then transmitted to a remote medium via lines of communication, such as a computer network, the internet, or another form of mobile communication. The odor type is received in the target computer. This detection stage can be completed in the target PC when necessary.

Today’s technology can only permit the transmission of odor data. In order to perceive the transmitted information at the target location as smell, the scents must be present as stored in containers and must be triggered via received odor data to be dispersed. The research in this field is limited, with ongoing pilot studies.

How can diseases be diagnosed with odors?

The natural functions of the human body, such as sweat, blood, urine, and feces, can be used to help diagnose diseases. The odor of the gases in human breath holds significant information regarding body health. There are between two hundred and four hundred different gases found in human breath. Furthermore, the number of gas types detected and described in the breath can exceed three thousand. While blood gets cleaned in the lungs, the gases of the used blood pass to the breath via the alveoli. Therefore, many critical pieces of bodily information are present in the breath.

The gases exhaled through our breath are composed of various alkaline and aromatic compounds. Each of these is a potential indicator that provides information about a disease. The gases and their ratio in the breath of a healthy person are well established. Since the ratio of the gases in the breath gets altered depending on the cause of an illness – such as diabetes (Type I and II), cancer of the ear-nose-throat, tuberculosis, and women’s reproductive diseases – can be diagnosed by utilizing the electronic nose.

There are other uses for the technology, too. NASA is developing a highly sensitive artificial nose for space research. This device will almost be able to distinguish every type of chemical compound, making more sensitive measurements than a human nose. With this device, the detection of harmful substances in the space station will be possible.

Google has announced that significant progress has been made regarding the “Google nose” which helped revolutionize searching for aromas. The Google Aroma database (http://www.google.com.tr/intl/tr/landing/nose/) stores more than 15 million kinds of scent. The days when we will be able to smell the scent of any product through our internet based devices do not seem to be too distant. To make this possible, sound waves would be converted into odor signals. There is a partially-imaginary video prepared to show how this can feel.

New technologies will change our relationship with smell, which has always been deeply important to humanity. Reference is made of this in the Qur’an, especially when the Prophet Jacob of Canaan sensed the fragrance of his son, Joseph, who was hundreds of miles away. The verse, from the chapter of Joseph, reads, “Surely, I sense the fragrance of Joseph, unless you would consider me a dotard. “It shows how valuable scent is to us, as anyone who has had a long lost memory triggered by an unexpected smell understands. As the verse suggests, losing our sense of smell is akin to losing our minds. Research has borne this out, as one of the first symptoms of Alzheimer’s disease is the loss of smell. In fact, monitoring loss of scent has helped with the early detection and prevention of Alzheimer’s. This is yet another way that our body has been perfectly calibrated to cue us in to its messages. In this regard, as with many, technology is still trying to catch up to nature.

(continued from the previous issue)

Using the distinct groves and folds on the hemispheres as a guideline, a map drawn on the cortex identifies focal points, where the various senses are concentrated, and activities in particular regions. Each of these different colored schematic centers has a specific name and performs specific functions. For example, the region above the neck at the back of the head (occipital lobe) is the field of sight; the sections that coincide with the temporal region is the field of hearing; immediately in front of this, on the left, is (generally) the field of speech; in the forehead region (frontal lobe), on the anterior wall of the middle canal is the initial center of planning of movement; on the top section of the front region is the field of complex movement; immediately behind here, in the middle-side region, is the field of simple movement; the area behind this, next to the hearing field and extending upwards, is defined as the touch receptive field. However, these areas are not confined, but rather spread out, and have a very complex connection network. The duty of the adjoining areas of these regions is to display and decipher the meaning of the signals received from the nerves. As the received signals regenerate past experiences and memories, the object or event sending the signal is recognized. To perform voluntary complex movements, the plan of movement must initially be defined in the mind and then the combination of this plan is conveyed through my nerve fibers to the movement regions. As complicated activities in humans, such as talking, and activities that involve the sensory integration mechanisms are miracles in themselves, it is quite astonishing that certain people claim that humans evolved from apes, later learning how to speak. The spinal cord (medulla spinalis) that extends from the skull in the form of a long cord, is the central nervous system sending signals to the body regions under the neck. The grey matter of the brain is located on the surface, while the white matter lies beneath the cortex; however with the spine, the butterfly shaped grey matter is inside, and the white matter on the surface covers the grey matter. In this central nervous system, all of the sensual messages that are received from the entire peripheral system, in particular from your skin and muscle, are immediately connected with the synapses or connections of the movement cells, and thus a spinal reflex is produced. As a section of the connecting cells (synapses) responds with a reflex, the other section transmits the signal to me to determine the appropriate voluntary response. For instance, if you tread on a nail, as the nail goes into the foot, a signal is transmitted by the sensor fibers to the spine, and to avoid a loss of time, the spine immediately signals the movement nerves before me, and a command is transmitted to your muscle you to raise your foot. And after your foot is saved by instant reflex, you begin to perform the other conscious activities, for example; you avoid putting weight on the foot, and bandage the wound if it is bleeding.

31 pairs of nerves (right and left) emerge from the spinal cord; 12 pairs from the brain area lay beneath the skull. These are all nerves that emerge from the central nervous system, and are distributed to various organs of the peripheral nervous system. All of the head nerves that emerge from the skull, with the exception of the tenth nerve, called the vagus nerve, control activities related to movement and senses in the head and neck region. Each of the 31 nerves exit from a space in the side of the vertebrae, and each of these nerves has two roots, an afferent nerve (sensual nerve), and an efferent nerve (movement nerve). These roots join immediately outside the spinal cord, and form the cords that carry the sensual and movement nerve fibers. These nerve cords are distributed in a plan and system that is specific for each organ. For example, the receptor sensor cells that sense a needle pricking your finger transmits this signal to the spinal cord through the receptor cell of the arm. The responsive reflex of pulling the hand away, a reflex from the spinal cord, is sent to the arm and hand muscles, and you pull your hand away. This is an example of a simple reflex. The movement nerve cells of the peripheral nervous system are divided into two, the somatic nervous system, which is distributed to the skeletal muscles, and the autonomic nervous system, which is distributed to the inner organs. Whilst the majority of the activities of the somatic systems occur voluntarily at the conscious level, the activity of autonomic systems is mainly involuntarily, or below the level of consciousness. The autonomic nervous system controls the smooth muscles of the heart, glands, blood vessels, respiration, digestion, urination and reproduction systems without our even realizing it. Dear Peter! Could you manage to do all this if you were in control? Your self control can only intervene until you place food in your mouth. Then the digestive secretions, the stomach and bowel activity, and the excretion of waste are all conducted automatically, totally beyond your control. Your breathing continues while you sleep, your kidneys never cease to function, your heart never rests, and your liver never relaxes while you sleep; your pancreas continues to produce insulin. All of your internal organs and blood vessels continue to function with the smooth muscles whenever necessary. And all this activity is conducted without you even being aware of it. If you tried to do all this, you would become exhausted within five minutes, lose interest and become unable to cope.

The nerve cords of the autonomic nervous system are divided into two, the sympathetic and the parasympathetic. These two systems have been created in such a way that they respond in opposition to one another, and every organ is provided with a stem from both. Therefore, no organ of the body is left uncontrolled. Whilst one signals and encourages the organ to function quicker and generate more outcomes, the other acts to the contrary, sending signals that encourage the organ to slow down. In which case, with these two contrasting signals, the organ protects its optimal functioning tempo according to the situation and conditions. The sympathetic system generally responds in cases of stress and shock, preparing the body for the effects of such situations. For example, an increase in your blood pressure, blood-sugar level, and perspiration, the dilation of your pupils, and an increase in the flow of blood in your muscles all occur from the effect of the sympathetic fibers. The parasympathetic system sends adverse signals, such as reducing blood pressure and so on, so that the organs return to their neutral state and continue their normal functions.

From the very beginning I have described many of my sections and signals, but I have not yet told you about my key to life, my nerve cells, and how my nerve cells function. 30 billion cells, known as neurons, are the actual units that function in every part of my system. A neuron has a cell body and emerging filaments like tree branches. The single thicker filament like the tree trunk is called the axon, and the thinner filaments that emerge in larger quantities like tree branches are called dentrites. The nerve signals advance from the axon to the dentrite in the form of an electrical pulse. In the space between the connection point (synapses) of a nerve cell axon and the other cells, the dentrite, a chemical substance, called the neurotransmitter, is released. When these substances, in the form of neuropeptides, amino acids, acetylcholines, and monomines, reach the wall of the opposite cells, it an electrical pulse is immediately ignited in the dendrite. Just like a row dominos, falling down one after the other, or football fans performing the Mexican wave, a wave-like effect is generated and these electrical messages are fired with great speed from one end of the cell to the other, advancing in the form of tiny electrical pulses to be transmitted to neighboring cells. While a cell at rest has a potential of 70m V, the action potential of up to +30 – +40m V can transmit all types of information. Every cell can transmit up to 1,000 signals per second.

While you still do not recognize the true value of what you call the memory, which records hundreds of experiences every day, various theories are presented regarding how this bank which stores information in your brain actually functions. But we all know that the answer to this question lies within the millions of neurons that constitute me. Just as all of the senses, thoughts and actions occur from electrical and chemical signals that are transmitted from one cell to another they are presumably recorded in the same way, that is, with electrical and chemical signals.

It is difficult to define a precise center for the boundaries of the memories in me; memory could be interconnected with all of my regions. The storing of certain memories, some voices, visions, smells, or dreams, or the sense of resentment, anger or joy, is all carried out in different forms. You could not even begin to imagine the greatness of the memory storage! I have two types of memory, one short and one-long term. In my short term memory, I can store up to between seven and nine different things at any one time. Nothing remains in my short-term memory for more than a few minutes. Everything that you remember after this is stored in my long-term memory. In my long-term memory things can remain for days, months or even years. Everything you know and learn is stored in your long-term memory. By the time you are eight years old, the information in your memory is enough to fill one million pages. However, this is a mere drop in the ocean; the long-term memory is so vast that it can never become full. Even when you reach a hundred, I will have the capacity to store new information, so never assume that you are overloading a child’s mind and never deprive them of education…Some presumptuous people say; “Never force a child to memorize at a young age, it will affect the brain.” Do not believe them! The learning of foreign languages, the Qur’an and religious education is recorded in my memory by electric pulses and this is so much easier and healthier in the early stages of life. In fact, such activities at a young age can even strengthen the memory. The event called ‘recollection’ is the repeat of the electric pulse codes that are recorded at the actual time of an event. Occasionally you try to remember a person’s name, and although the name is on the tip of your tongue, you just cannot remember. You struggle and eventually give up. Then suddenly, two days later the name comes to your mind. You are quite puzzled and of course pleased that you have remembered, but have you ever wondered how this happens? As you try to remember, you control each of my nerve cells individually, because you are not sure where you placed the files that bear this information. But you are unable to find which section of the millions of cells bears the information. As you have not used this information often, or because you did not consider it to be important, you did not register it in a particular place. But you would never forget your father’s name, as it is important to you and use it often, so the file is in front of you constantly. Well, you get frustrated at not being able to remember and stop searching; however, what you call the subconscious is in fact a much more mysterious mechanism. It begins to search without you being aware of it. Then to your surprise it produces the file two days later. The subconscious is a very mysterious place, it affects everything about you. Only the most sincere feelings are recorded in the subconscious; no veil, no hypocrisy, only actual thoughts are recorded. And also events that deeply affect you, the sad or bad memories you experience, and of course sins…The subconscious is what causes the sense of guilt or an inferiority complex; this is reflected in much of your behavior. But problems like guilt or an inferiority complex are something we can change; it all depends on you. If you are a person who has self-control, you perform good, favorable deeds, and are continuously patient; thus you can eventually renew the contaminated sections of your subconscious so that it will not upset you anymore. Indeed, this is the reason why, of all the creatures on earth, only humans were blessed with the sense of remorse and faith. If you suppress feelings of guilt and sin in the subconscious, the autonomic system affects the organs without you even realizing it; the thalamus, hypothalamus, or the pituitary gland (hypophsis), which are small in size, but bear a great responsibility; eventually this disturbs the balance of the whole body and you become ill. Although this may not be an organic complaint at first, due to psychosomatic symptoms which are caused by suppressing your subconscious, over time this will affect the functions of one of your organs and you become ill. Of course the exact opposite is also possible, with inspiration, pleasant thoughts and good actions the positive signals transmitted to the affected organ may possibly be the means to recovery.

Dear Peter! I have so many more facts and mysterious functions to describe to you, but unfortunately the pages here are not enough. Well, I suppose I must stop somewhere. I really wanted to talk to you about a number of different things, like dreams, mental illnesses such as Parkinson’s, Alzheimer’s, strokes, sleep, hypnosis, and the damage caused by drugs. However, each of these subjects is so vast, and many of them have already been explained in previous issues, so for now I will leave it to others to describe these subjects to you, and say my last words…

Dear Peter!… While your hand is writing and reading these words, or explaining what you have read to your friends, or learning all this information and passing it through the filter of thought, you are constantly using my nerves and my systems. There is not a single moment where I am not informed of events that occur in your body. Who knows just how much of the mysteries in me you will use in order to rise to the peak of accomplishment with the blessings that have been bestowed upon you by the Creator. Even the greatest computers made by human beings are mere toys compared to me. Nevertheless, the knowledge of engineers and craftsmen which design, plan, and place every piece into these computers with total accuracy is only possible because of me. Presumably you are not denying those who designed, constructed, and made the computer operate, are you? In which case you should thank God, the One who created me, an organ whose capacity exceeds that of thousands of computers, with His eternal power and wisdom; always remember to use me in good, blessed, and honest actions!…May God protect you!…

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

When we have been sitting or lying for a long time we can suffer from orthostatic hypotension due to an insufficient operation of the sympathetic nerves.

When we are lying down, the blood pressure in our arteries is pretty much equal throughout the body. When we stand up, the blood pressure is affected by the gravity and increases in the vessels under the heart, while decreasing in the brain. If we lie down again, the blood pressure in the arteries balances once again. If these changes cannot be naturally controlled, then we may suffer an increase or decrease in blood pressure, which could result in a fatal injury.

There are baroreceptors in the walls of main arteries whose tasks are to measure constantly the blood pressure and to send data (electrical signals) to the brain, informing it about the blood pressure in the body. These baroreceptors are located in the aorta as it leaves the heart and in the carotid artery as it enters the brain. With the onset of hypertension, the frequency of the signals that are sent to the brain increases and this drops in case of hypotension. The center of vessel movement in the brain, with regard to the frequency of electrical signals it receives, perceives a low or high blood pressure.

In the brain is a vasomotor center; this continuously controls the blood pressure and regulates it. This center constantly receives data about blood pressure. If the pressure decreases, the signals of the sympathetic nerve increase. If the pressure increases, the signals to the parasympathetic nerves are suppressed. As a result of sympathetic irritability, the heart begins to beat faster and stronger. It pumps much more blood in a unit of time, and thus the blood pressure increases. The arteries and veins also constrict and owing to this constriction in the arteries, the blood pressure increases further. As a consequence of constriction in the veins, the extra blood that is stored inside the veins is pumped into the heart. Now, as the heart is receiving greater volumes of blood, it works faster and contributes to the increase in the pressure. In the meantime, as a result of the suppression of parasympathetic nerve signals, the heart contracts faster and stronger, thus pumping much more blood.

As the blood pressure rises, the mechanism which is in charge of reducing the pressure via vasomotor center is triggered. While pressure is applied to the sympathetic nerves, the signals that are being sent to the heart and vessels decrease. Thus, the rate of systole and the amount of blood which is being pumped decreases. As the arteries receive less blood the volume of blood in the system falls off and as the arteries and veins expand, the blood pressure falls. Due to the dilatation in the veins, the volume of blood which is sent to the heart also decreases and as a result the heart pumps less blood and the blood pressure drops.

However, by triggering the parasympathetic nerves, the signals that are sent to the heart increase. This helps to slow the heart down and ensures that there is less blood pumping through the system. As a result, the blood pressure which has been reduced via the sympathetic system is reduced even further with the parasympathetic system. At this point, it is necessary for there to be a rapid drop in blood pressure, which is provided by the simultaneous functioning of different mechanisms.

We cannot control this system and it acts extremely rapidly and with great elegance. Even in the systole period, when the heart is pumping the blood and there is a short and sudden increase in pressure and in the diastole period, when the heart relaxes and there is a short and sudden decrease in pressure, the system is in charge and functioning at every second, operating to increase the hypotension and to decrease the hypertension. The average healthy human heart beats 70 times per minute. Consequently, there are 70 systole and 70 diastole stages every minute; thus a normal balance can be maintained by decreasing the pressure, which increases 70 times every minute, and by increasing the pressure, which decreases 70 times every minute; this is how the body maintains a normal balance. In other words, this system functions 140 times every minute. Is it possible that this system, which operates throughout our life, a system that we are not aware of, a system that is so sensitive and vital to our lives, a system the details of which have only recently been understood after centuries of observation could be nothing more than a coincidence?

The pressure regulating system mentioned above carries out other important tasks while we are sitting and standing as well. The amount of blood going to the brain is related to the maintenance of a difference in blood pressure between the arteries and veins and to the recirculation of blood. In connection with hypotension, the pressure in the veins to the brain decreases, in order to partially compensate for the decrease in the arteries. By preventing a decrease in the difference of pressure (perfusion pressure) between the two systems, the continuity of blood going to the brain can be maintained.

In addition, a small decrease in the blood going to the brain can lead to an increase in acidity and carbondioxide in the brain tissues and to a decrease in oxygen; this results in the dilatation of the blood vessels in the brain. When these systems go into action anyone who is not suffering from orthostatic hypotension will have a stable amount of oxygen consumption in the brain when they stand up, and thus not experience dizziness.

In fact, scenes from karate movies are wonderful displays of the perfect functioning of this system. In such scenes, the fighter will jump up, and then suddenly fall to the ground; he will then suddenly spring up and performs different moves. Certainly with every movement, the blood pressure changes suddenly, but as a sign of the Creator’s mercy and grace, the body is able to maintain a balance. Should not the person watching these scenes stand in amazement, thinking: “Oh my God, what an incredible order! How great is Your knowledge, power, wisdom and art!”

As mentioned at the beginning of the article with reference to an actual sad incident, when a person whose sympathetic system is not functioning normally suddenly stands up, they can suffer from dizziness and perhaps even faint due to irregular blood pressure.

For patients suffering from orthostatic hypotension patients, it is important that they do not stand up rapidly. In addition, exercises that encourage the use of leg muscles before standing up will help pump blood towards the brain.

Pause for a minute… What would happen if this miraculous system did not exist? Consider how much time it would take you to merely get out of bed every day!

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. 

Adam forgot, so did his children.

How does our brain store information? How is it possible to make learning faster and easier? Is there any way not to forget what we have learned and to remember things more easily? Of what importance is the fact that information is never deleted from our memory, even if we have forgotten it? These are among many of the questions for which answers have been sought over the years.

Memory is one of the functions of the brain and it is defined as the ability to preserve acquired information consciously and relate it to the past. It is not just a certain portion of the brain, but rather the entire organ that functions in storing, processing, and retrieving external and internal signals. Signals that build up our memory are what we usually perceive through our five senses. When we burn our hand, or see or experience a traffic accident , when we are given a compliment and many other events are all examples of external signals, whereas internal signals are related to our nervous system or imagination. The pain one feels during a heart attack, the anxiety of a cold sweat, or a beautiful daydream are all stored in our memory too. We may or may not remember them. There is no deletion; it is simply that we do not remember. Forgetting is a state that is encoded in our makeup with differing degrees, depending on the kind of life the person has experienced. Age, gender, stress, habits, and illnesses all have varying roles in forgetting.

Short-term memory

Short-term memory refers to saving and remembering what we have learned a few seconds or minutes ago; the prefrontal brain is the location for this temporary processing. Signals are kept in this portion of the brain for a few seconds and then conveyed to the back stage (as in the transfer of data from the cache memory to the main memory in computers). We tend to quickly forget those things on which we have not spent a long time or to which we have not assigned great importance, even though we can understand them. Imagine how unbearable our life would be if we were to store in our memories and remember things in infinite detail like the color of the wall we are facing, the variety of the objects around us and their qualities, the air we breathe in and out, or every beat of our heart. The signals that come to our brain within a certain time frame are filtered according to our needs and their significance and limitations are applied depending on their qualities and quantities.

There is no consolidation processing for short term memory. Second or minutes after signals are received they are retrieved in accordance with what we need; if they are insignificant for us, they are forgotten in the same amount of time. The information that is significant for the person is consolidated in the hippocampus and reserved in mid and long-term memory units.

Mid and long term memory

After being processed in the sub-cortex (limbic system) of the brain, signals are saved. Depending on their level of urgency, the meaning they stand for, and their emotional effect, signals are saved in either the mid or long term memory. Pain, joy, pleasure, and fear are states that solidify memory traces. A heart attack, the infliction of wounds and bruises or humiliation, accidents, visits from a loved one-these are all examples of events that are easily remembered. However, a lasting record is almost impossible to attain if the subject is something that has been forced (like a student studying for higher marks) or if the subject does not appeal at all. Consolidation is necessary to make a short term memory a lasting one. However, if a student is curious about the subject and enjoys what he or she is learning, then long term memory is possible without too much effort in consolidation. Forced consolidation (e.g. a student’s orientation to attain higher marks) requires a longer period. The information is consolidated more easily when a person is in a sound and alert state of mind.

Storage in the long-term memory does not occur immediately after something has been learned or experienced. For this storage to be possible at least an hour needs to pass to synthesize the memory proteins that are responsible for recording. If electric shock is applied to a person’s brain immediately after an unforgettable event, they will not be able to remember the event. But if the electric shock is applied an hour later, the memory remains.

Once stored in long-term memory, information can be retrieved, even after months or years. When new information is obtained older information is called up and they are saved with a new pattern of storage, with the newcomers being related with the ones that have already been stored; it is in this way that long term memory is generated.

It has been argued that RNA has a role in storing old information. In experiments, guinea pigs were taught information through repeated practice which is stored in their long term memory. The brains of these animals were later minced up and fed to other animals. It was observed that those animals which had been fed the brains learned faster and more easily than other animals that had been fed on a diet that did not include the brains. This shows us that information encoded in the memory is not lost; rather it is transferred with the help of certain molecules. It is also known that DNA is related to genetic memory.

It has been found that people with good memories have a greater number of nerve cells and channels of transfer in the memory-related zones of their brains (cortex, corpus callosum, hippocampus, thalamus, hypothalamus, limbic system, amygdale, temporal lobe, and prefrontal cortex), while there are less cells in other zones of the brain. Nerve cells are stimulated while signals are stored in one’s memory. Even if a person has a weak memory, activities like reading, memorization, or other engagements that improve love, happiness, and peace of mind may help long-term memory.

Forgetfulness

It is important to find out whether forgetfulness occurs because of an illness or something else. Age is one major factor. Forgetfulness in an aging person is proportionate to the number of the loss of cells.

Stress, dealing with multiple things all at once, or occupying oneself with things that are of no benefit, that is, creating a pollution of information, all affect short term memory and may cause forgetfulness.

Forgetfulness due to damage or illness

If the nerve cells of the lower occipital lobe of the brain are damaged, old information cannot be retrieved. Likewise, in case of damage to the nerve cells that are found in the temporal lobes on the sides of the brain, or due to an insufficient intake of B3 and B12 vitamins, cerebral hemorrhage or an embolism in the veins of the memory zones forgetfulness may occur.

Patients with Alzheimer indicate short term memory loss. They tend to forget visitors’ names, daily events, or the doctor’s advice.

Chronic alcohol abuse may cause damage in the hippocampus and thus in the ability to encode information.

Electroshock may also delete recent information that has been recorded in the short-term memory. Thyroid failure, Parkinson’s, hydrocephaly, schizophrenia, brain tumors, and epilepsy may also cause forgetfulness.

Some advice

Spiritual teachings and religious services have many positive aspects in our lives in addition to being our duties for expressing our servanthood to God Almighty. In Islam, for instance, principles like “enjoining good and forbidding evil,” praying at night, a brief afternoon nap, staying away from what is forbidden, reading and/or memorizing the Qur’an, and other activities may provide some protection against forgetfulness.

It is also claimed that keeping oneself busy with things that are considered morally improper, not least things that are sexually provocative in an illegitimate way, may damage neurons that are operative in memory. In order to be less affected by forgetfulness in our advanced years, it can be helpful to read spiritually and intellectually useful material, to learn and memorize new words and concepts, to keep oneself in good moral condition by engaging in charity work and helping others, and to maintain good sleep and a healthy diet

On the other hand, thinking a bit more wisely, to be able to forget (not forgetfulness) also has many benefits. Our nervous system is relaxed by forgetting, otherwise it might collapse. Forgetting old informa¬tion could well open up room for new information, although this does not mean that the information is deleted from memory; it is retrieved when needed. But, if forgetting reaches a level that is above medically ex¬pected averages, then medical help should be sought.

There are incidents of patients who are suffering from dementia and Alzheimer regaining their memory after electroshock therapy. Perhaps this is evidence that we will remember and testify for all our actions when we will have to account for them.

The human ear and hearing

The human ear can be divided into several functional sections: the outer ear, the middle ear, the inner ear, and the auditory nerve. Sound goes through a series of changes as it travels through these sections until reaching the brain. The outer ear picks up sound pressure waves, amplifies them and then converts them into mechanical vibrations on the ear drum, which is connected to a series of small bones in the middle ear. These small bones further amplify or diminish the mechanical vibrations in the ear drum and transfer them to the cochlea, a snail-shaped cavity filled with fluid which is located in the inner ear. Change in fluid pressure caused by vibrations within the cochlea lead to changes in the flexible membrane, called the basilar membrane. These changes contain information about the frequency and strength of the sound that has entered the ear. Attached to the basilar membrane are mechanical receptor cells, called hair cells, which are bent according to the deflections of the basilar membrane.The hair cells have hair-like structures. The bending of these hairs assists the release of an electrochemical substance that causes neurons to send electrical signals to the brainstem through the auditory nerve. These signals are in the form of a message (or a code) that the brain understands.

Cochlear Implant (CI) devices

If there is a broken link in any part of the auditory pathway, the brain does not receive any coded signals, and hearing impairment occurs. If a large number of hair cells or auditory neurons in the cochlea have been damaged, then the person is diagnosed as profoundly deaf. The hair cells can be damaged by certain diseases (e.g., meningitis, Meniere’s disease), by congenital disorders, by certain drug treatments, or by other causes. One negative outcome of damaged hair cells is that they can subsequently lead to the degeneration of adjacent auditory neurons. Research has indicated that the most common cause of deafness is the loss of hair cells (>95%) rather than the loss of auditory neurons. This has encouraged scientists to try implanting a device inside the iner ear or cochlea, bypassing the normal hearing mechanism of the ear, to stimulate the remaining auditory neurons directly through electrical signals. These are called Cochlear Implant (CI) devices, which can restore partial hearing in profoundly deaf people . A standard CI system, shown in Figure 1, composes of and performs the following functions: a microphone picks up sound pressure waves and converts these into electrical signals. The signals are sent to the speech processor that is worn by the patient. The speech processor analyzes and encodes these sound signals, sending them back to the external pick-up coil . After passing through a wireless radio link that lies between the external and implanted coils and an implanted electronic devise, coded signals are sent to the implanted array of electrodes in the cochlea to electrically stimulate the remaining auditory neurons , and the brain receives what it interprets to be sound.

Electrical stimulation of the ear, or CI research, can be traced back to the 1800s. The Italian scientist Alessandro Volta used a battery as a research instrument to demonstrate that electric stimulation could result in a number of human sensations . After connecting a 50- volt battery to his ears, he noted that “…at the moment when the circuit was completed, I received a shock in the head, and some moments after I began to hear a sound, or rather noise in the ears, which I cannot well define: it was a kind of crackling with shocks, as if some paste or tenacious matter had been boiling…”. That electric stimulation of the auditory nerve provides hearing sensation in deaf people was reported more than 100 years after Volta . Electric stimulation in two deaf patients resulting in hearing was reported in 1957. These successes resulted in intensive research into helping deaf people hear in the 1960s and 1970s. One of the early successful single-channel CI devices was developed in the early 1970’s (3MCorp/House) and became the first commercially available CI device approved in the United States in 1984. The University of Utah developed a six electrode implant called the Ineraid or the Symbion device in the early 1990s. It was followed by other devices in Europe, the United States, and Australia.

The present status of Cochlear Implants

Today, around 10% of the population in developed countries suffers from hearing impairment. At present, the number of CI users has reached more than 100,000 worldwide, and is still growing rapidly. Functionally, CI has evolved from the single-electrode device that was used as an aid for lip-reading and

sound awareness to a modern, multielectrode device that can allow an average user to talk on the telephone. Even though significant technological progress has been achieved in the last 50 years, there are still many mysteries about the human hearing process and the parts of the ear. Here, we will compare some aspects of the healthy human ear and CI devices, looking to the future. The human ear operates over a range of sound pressures (its dynamic range) which is greater than one million to one (120dB), with as many as 200 discrete steps in the range. In contrast, today’s CI devices typically provide a dynamic range of three to one (10dB) to ten to one (20dB) with 20 discrete steps. This major difference is mainly due to the fact that the human ear is very adaptive in noisy environments, and is able to suppress noisy background, while picking up and processing appropriate sound signals for better perception. CIs do not differentiate between sounds, but amplify all sounds, which results in poor sound perception. Today, a typical multi-channel CI system uses 16 to 24 electrodes implanted in the cochlea with 8 to 22 signal processing channels. A potential shortcoming of having so many electrodes and channels in current CI technology is the electrical interference of electrodes during simultaneous electrode stimulation. These electrical interactions can disrupt the stimulus waveform prior to neural activity and degrade sound perception. The normal ear contains roughly 3,500 inner hair cells in the cochlea that are tuned to different frequencies from 20 to 20,000 Hz. They are connected to about 35,000 auditory nerves. Hair cells work as signal processing channels, yet each of the inner hair cells has also been wired in a sophisticated and little-understood fashion to 10-20 auditory nerve fibers that carry information to the central nervous system. Since they work in the chemical domain, they do not have the gross interference issues of CI electrodes. While good speech understanding has been achieved by users of modern multi-electrode CIs operating in quiet environments with 70–80% sentence recognition, allowing users to talk on the telephone, the CI devices do not discriminate between noise and the meaningful signals, only achieving speech understanding at between 70% and 80%, which falls to 10% or lower in noisy environments. It is a great challenge for CI users to appreciate music. Some CI listeners reported that they can enjoy music and are able to recognize melodies, but most described musicas sounding unpleasant and noisy, and performance could not be increased with current CI technology. CI users have difficulty in identifying differences in frequencies. Typically, they cannot discriminate any frequency difference for frequencies higher than 500 Hz, while the normal ear can hear up to 20,000 Hz with frequency discrimination between 2 to 3Hz at best. This gross difference is related to the issues surrounding signal processing strategies and electrodes of current CI systems. Predicting post-surgical performance based on presurgical conditions and tests of a CI candidate is still a problem for the physician. The cost of surgery is still high; in the United States, for example, a typical cost is between $40,000 and $75,000. Beyond these issues, the moral, cultural and ethical issues related to CIs are very complex. They are still debated, and are an important part of CI development in the world today. The hair cells in the human ear naturally deteriorate and die as we grow older. This process is typically sped up with exposure to loud noise. In common with all mammals, new hair cell generation in human ears stops right after the birth. However, in fish and amphibians, very similar cells are present and reproduce throughout life. Recently, it was found that hair cells of birds are repaired after being damaged by exposure to noise or ototoxic agents. It was also discovered that hair cells in the mammalian vestibular (balance) organ, very similar to those in the hearing system, can regenerate. These findings, along with other advancements in medical fields, lead to long-term research into different aids for hearing- impaired people. Despite the fact that hearing loss is usually permanent, scientists are optimistic that it may eventually be possible to reverse the damage in the ear by repairing or regenerating the sensory hair cells through gene therapy, stem cell transplantation, or ultimately by replacing the human cochlea with an artificial one. Today, Auditory Brainstem Implants are also being tried on humans for direct brainstem stimulation, bypassing the ears and the auditory nerves. Human beings and most animals on earth are born and equipped with a pair of ears for a good reason: having two ears enhances hearing and sound localization. Scientists are examining whether this is also true for deaf children who receive not one, but two CIs.

Conclusion

The sense of hearing is a gift for human beings which they hold dear and are grateful for, as much as for any of the other senses with which they have been equipped. It is important to strive to find cures for all kind of diseases, yet, more important than the cure is prevention of harm to our body and its amazing senses. Here, we have tried to open a small window onto human hearing, to examine how related impairments are being dealt with through cochlear implant (CI) devices, as well as looking at the issues related to these devices and the future directions of research for restoring hearing to deaf people. It is obvious that we have learned much about human hearing and ear in the past century; yet, this may well be just the tip of the iceberg.

References

1. S.U. Ay, F.-G. Zeng, B.J. Sheu, “ Hearing with bionic ear,” IEEE Circuits & Devices Magazine, Vol. 13, No. 3, pp.18-23, May 1997.

2. F.-G. Zeng, “Trends in cochlear implants,” Trends in Amplification, Vol. 8(1), pp.1-34, 2004.

3. A. Volta, “On the electricity excited by mere contact of conducting substances of different kinds,” Royal Soc. Philos.Trans., vol. 90, pp.403 431, 1800.

4. A.M. Andreev, G.V. Gersuni, A.A.Volokhov, “On the electrical excitability of the human ear: On the effect of alternating currents on the affected auditory apparatus,” Journal of Physiology USSR, Vol. 18, pp.250-265, 1935.

The discipline in which medicine and engineering truly meet and face new challenges is the field of “biomedical engineering,” an emerging discipline that is only a few decades old. In each sub-specialty of biomedical engineering, researchers study the human body, develop new materials and structures using engineering sciences, either as a treatment method for disease (e.g. artificial bone implants, artificial blood, vascular stents, cardiac valves, etc.) or to diagnose them (e.g. imaging methods and other diagnostic instruments in hospitals). Biomedical engineers face the incredible challenge of developing materials and devices that are compatible with biological systems and capable of working inside the human body to substitute bodily functions. Needless to say, the extreme complexity of the human body makes it impossible to mimic the original system or function of the organs in any way. However, even a poor replacement part or a functional improvement provides great benefit to the patients.

One of the most complex systems of the human body is the nervous system, which consists of the central area (the brain and the spinal cord) and the peripheral parts. The branch of biomedical engineering that deals with the nervous system is “neural engineering.” In this article, we will touch upon a specific subject in the broader area of neural engineering, that is, “neural prosthetics.”1 As the name implies, neural prosthetics is an area where engineering knowledge is utilized to treat neural disorders.

The building blocks of the nervous system are called “neurons.” Neurons generate electric pulses to communicate with each other. The fact that these electric pulses can be elicited by artificial means, i.e. by applying small electric currents to the neurons externally, forms the very foundation of the field of neural prosthetics. Neural engineers can input information into the nervous system by taking advantage of this phenomenon, called “neural stimulation.” Likewise, the information content of neuronal activity can be deciphered by recording the electrical pulses from the neurons and interpreting them according to neuronal function. This two way traffic, monitoring and controlling the neural activity, allows researchers in this field to develop methods of treatment for some sensory, motor, and psychological disorders.

Some of the most successful neural prosthetic applications have been in deep brain stimulation in Parkinson’s disease,

cochlear prosthesis in hearing impairment, bladder emptying and respiration in spinal cord injury, and vagus nerve (10th cranial nerve) stimulation in epilepsy and psychological depression. These are neural prostheses that are readily available as a treatment method for the given ailments. There is a whole host of others that are in the research and development phase. We will review a couple of examples.

In certain diseases of the inner ear hearing is lost as a result of damage to the hair cells inside the cochlea. In normal cochlea the sound information reaches these hair cells after traveling through the ear drum (tympanic membrane) and the structures of the middle ear, causing them to vibrate. This vibration of the hair cells is mechanically transported to the spiral ganglion cells that form the hearing (auditory) nerve. The hearing nerve carries the sound information to the brain in the form of electric pulses. The ganglion cells are healthy and functional even if the entire population of hair cells has been lost as a result of disease. Neural engineers take advantage of the fact that the spiral ganglion cells (which normally accept input from the hair cells) can be electrically stimulated, thus mimicking the function of the hair cells and producing the sensation of sound.2 During a simple surgical operation, the surgeon inserts an electrode into the ear canal which spirals into the lumen of the cochlea so that the sites where the electric current emits from the electrode are adjacent to the spiral ganglion cells (Figure 1). To summarize the principle of the operation; the audio signals are captured by a microphone, processed, converted into electric pulses (A in Figure 1), and transmitted to the implant over a transmitting antenna (B in Figure 1), or headpiece, held in place by magnets. The implant (C in Figure 1) applies the signals to the ganglion cells in the cochlea through tiny electrodes (D in Figure 1). The hearing nerve (auditory nerve) carries the sound information to the brain, where it is “heard.”

Even though the human spiral ganglion has tens of thousands of nerve cells that provide a rich sense of hearing, the cochlear implant, using only six stimulation contacts, can produce auditory perception with sufficient fidelity to enable a deaf individual to use an ordinary telephone.3 Individuals with cochlear implants can also improve their hearing with practice. Thousands of patients have been implanted with cochlear prostheses to date, including children.

The second neural prosthesis application we will review is the retinal prosthesis, which, unlike the cochlear implants, is still in the research phase. Retinitis pigmentosa and age-related macular degeneration both lead to photoreceptor degeneration in the eye and result in a significant visual deficit or blindness.4 A growing body of research supports the feasibility of replacing the function of the photoreceptors with an electronic device. 5–7 A retinal prosthesis is analogous to the cochlear implant in many ways. In a healthy retina, the photoreceptors initiate a neural signal in response to light. In a retinal prosthesis, electrical pulses are utilized to initiate a neural response in the remaining cells of the retina, the bipolar and ganglion cells. It is hypothesized that the perception of shapes and images will be possible through pattern stimulation of the retina. Initial results are encouraging, but the quality of vision that can be attained with this approach is still a question to be answered. A conceptual retinal prosthesis system is shown in Figure 2. The system consists of an external unit coupled to an implanted stimulator with a wireless link. A video camera in the external unit captures an image and converts it to digital data. The implanted unit receives the signal, recovers power and data from the signal, and generates the stimulating current. The stimulus pattern is applied to the retina via the electrode array, which contains distinct electrodes that interface at many locations on the retinal surface. Recent implants in human subjects suggest the feasibility of this approach where individuals attain perception of bright dots in the visual field called ‘phosphenes.’ Furthermore, blind subjects are able to perceive edges when a few of these bright dots are lined up in their visual field.

Figure 3: A conceptual diagram of a Brain-Computer Interface for high level spinal cord injury or patients with ‘locked-in syndrome’ (adapted from Wolpaw et al., see note 9). The recorded neural activity from the motor cortex is processed and converted into command signals to control, for instance, a wheelchair, or to generate electrical signals to activate hand muscles for grasping an object.

Both cochlear and retinal implants are sensory prostheses, i.e. aids for sensory impairments. Another family of neural prostheses deals with motor impairments. Severe motor disability results from high level spinal cord injuries (quadriplegia) where most of the body is paralyzed, sparing only some face, neck, and shoulder muscles. Quadriplegic individuals are in extreme need of a means to control their environment; they need to be in control of their wheelchairs, bed, the room temperature, lights, TV, etc. Because of the level of paralysis it is impossible for them to generate any control signal, except perhaps by sipping or puffing on the end of a tube, which produces a very poor control signal. In the case of a ‘locked-in syndrome’ the condition of the patient is even more serious, with only some functions remaining in the facial muscles. The term ‘brain-computer interface’ has been coined to refer to attempts whereby the motor output of the brain is recorded and interpreted to generate the control signals needed by these patients (Figure 3,9). The ultimate objective of this research will be accomplished when the patients are able to control anything they need to control in their environment, including a computer. The brain-computer interfaces vary in the invasiveness of the approach. The least invasive methods utilize the electroencephalogram (EEG) signals recorded from the scalp. Unfortunately, the signal quality is poor and only ‘on/off’ type of command signals can be generated using this method. In the most invasive, yet most successful applications, an array of electrodes is implanted directly into the motor cortex of the brain at a depth of a couple of millimeters. The recorded signals contain volitional information as the patient makes intentions to move their arms or legs. These signals can be controlled by the patient, and they can in turn be used to control their environment. The current level of success in this type of BCI allows the user to have three dimensional control of a robot arm. This is of invaluable benefit to a quadriplegic individual.

Concluding Remarks: Reflections on Divine Wisdom

Even the subtlest parts of the nervous system are extremely complex. Just to name a few examples, from the highest centers in the brain down to the skeletal muscles in a descending order; the neural circuits of the short-term memory in the hippocampus, fine motor control circuits of the cerebellum, central pattern generators in the spinal cord, and even the control of skeletal muscles in graceful movements of the limbs are impossible to reproduce by artificial means. The Seal of Divine Design is clearly visible in these neural systems, as they are far more complex, far more compact, and far more functionally efficient than any system engineered by mankind. If anything, the growing experience in neurosciences teaches us that the vertebrate nervous system is full of wonders of engineering design. Therefore, it is a great blessing to be a student of both neurosciences and engineering disciplines. This bestows neural engineers with a unique perspective to understand the beauty embroidered into the human nervous system and contemplate on the Divine Wisdom. In spiritual terms, we may think of the human nervous system as a window opening to the works of Divine Wisdom, with manifestations of His Beautiful Names at the brightest level. It is an overwhelming joy to be able to open this window a crack, once in a while, and take a little peek.

References

1. Wise, K.D. ‘Silicon microsystems for neuroscience and neural prostheses,’ IEEE Engineering in Medicine and Biology Society Magazine, vol. 25, no. 5, pp. 22- 29, Sept.-Oct., 2005.
2. G.E. Loeb, ‘Cochlear prosthetics,’ Annu. Rev. Neurosci., vol. 13, pp. 357–371, 1990.
3. J. Helms, V. Weichbold, U. Baumann, H. von Specht, F. Schon, J. Muller, B. Esser, M. Ziese, I. Anderson, and P. D”Haese, ‘Analysis of ceiling effects occurring with speech recognition tests in adult cochlear-implanted patients,’ ORL J. Otorhinolaryngol Relat. Spec., vol. 66, no. 3, pp. 130–135, 2004.
4. E.L. Berson, ‘Retinitis pigmentosa. The friedenwald lecture,’ Invest Ophthalmol. Vis .Sci., vol. 34, no. 5, pp. 1659–1676, Apr. 1993.
5. E. Zrenner, ‘Will retinal implants restore vision?,’ Science, vol. 295, no. 5557, pp. 1022–1025, Feb. 2002.
6. J.F. Rizzo III, J. Wyatt, J. Lowenstein, S. Kelly, and D. Shire, ‘Perceptual efficacy of electrical stimulation of human retina with a microelectrode array during short term surgical trials,’ Invest. Ophthalmol. Vis. Sci., vol. 44, no. 12, pp. 5362–5369, 2003.
7. M.S. Humayun, J. Weiland, G. Fujii, R.J. Greenberg, R. Williamson , J. Little, B. Mech, V. Cimmarusti, G. van Boemel, G. Dagnelie, and E. de Juan, Jr., ‘Visual perception in a blind subject with a chronic microelectronic retinal prosthesis,’ Vision Res., vol. 43, no. 24, pp. 2573–2581, 2003.
8. Weiland, J.D. and Humayun, M.S., ‘A biomimetric retinal stimulation array,’ IEEE Engineering in Medicine and Biology Society Magazine, vol. 25, no. 5, pp. 14-21, Sept.-Oct., 2005.
9. Wolpaw J.R. et al., ‘Brain-computer interfaces for communication and control,’ Clinical Neurophysiolology, vol. 113(6), pp. 767-791, 2002.

Termites, one of the most common insects in the ecosystem, have very interesting specifications and social behaviors. These insects are of interest due to their ability to digest cellulose and to recycle organic foods found in rotten leaves, dead wood or wood chips. Although they are considered by some to be harmful to the economy-in the USA alone 600 million dollars every year-because they eat wood, in truth they bring about more benefit than harm. As a result of the activities of these insects, our forests are able to respire and regenerate. Termites break down old, decayed, and fallen trees, digesting them and thus helping nature to renew with a continuous circulation of vital substances. Despite the depth of information that is known about the ecological and economical importance of termites, only a little is known about their biological structure and behavior. Two characteristic features of these insects are that they live in social colonies and that they are very susceptible to infections, as they build their nests in soil or rotten wood. Since their environment is covered with damp and warm earth, they are also surrounded by an abundance of bacteria.

How termites arrange their social lives and how they protect themselves against illness are two main subjects being investigated by biological scientists. When termites encounter fatal fungal infections, the termites that first become aware of the disease start to send warning signals to the other members of the colony. Even at the cost of their lives, these members will continue to send warning signals. That is, for the health and prosperity of the whole society, some individuals of the group will sacrifice their own lives. One of these signals consists of the contractions and vibrations sent by the termite that caught the disease. One type of termite that makes its nest in wood starts to eat and destroy its nest when it catches an infection. The vibrations and sound of this activity are received by the other members of the colony, and they quickly realize that they are faced with an emergency situation. They then spring into action to move their nest to a more secure place. These communication experts exhibit different movements and behavior in order to inform others of different kinds of dangers. They use different methods to warn others about the existence of an intruder, or a hole in the nest, or a disease they have caught. Consequently, the vibrations and oscillations caused by the movements of the termites constitute a kind of Morse code for termites. In other words, termites talk to each other through these oscillations and vibrations, which to us appear as no more than a strange puzzle for us.

J. Traniello from Boston University investigated the communication systems termites use to inform each other about disease-making microorganisms as his research subject (Mechanisms of Disease Response in Termites) . He made a rectangular shaped Perspex (clear acrylic) nest which he has divided into two sections. The material used for the divisions allowed the termites to pass from side to side. Moreover, some tubes were also placed around the nest so that the termites could leave the nest. He placed termites in both of the sections. After an adaptation period, one part of the nest was infected by spores of a fatal fungus called Metahizium anisopliae, with the change in the behavior of the insects being observed and recorded. Termites that sensed the infected parts of the section started to move their bodies up and down and back and forth, as if they were breathing deeply and continued to depict seismic waves like oscillations and vibrations. Termites in the clean part of the nest felt these vibrations and within an hour had completely abandoned the nest. An interesting observation in the experiment was that the termites in the infected part stayed in the nest and continued to vibrate. In order to determine that the termites left the nest only after receiving the vibrations sent by the termites that had detected the infection, sound absorbent foams were placed between the sections, and the same experiment was carried out three times more. In the experiments conducted with the absorbent foam, despite the existence of the disease, the termites in the uninfected sections did not leave the nest. This proves that termites were receiving the vibrations from the infected termites and were replying to them by immediately deserting the nest.

It was thought that the termites in the infected area would also leave the nest after sending messages to the termites in the other section. This hypothesis, however, proved to be false. They stayed where they were and continued sending warning signals until they died. This was another example of the sacrifice observed in social insects that give up their own lives for the continuation of their society. The termite perceives the existence of a fatal bacteria attack and immediately starts to send warning signals; and by not abandoning their nest, they successfully put into effect a quarantine system. These social insects, without any intelligence, apply the quarantine system in such a precise manner that the disease is completely prevented from spreading. What is more, by sacrificing themselves for their society, they show that the principle of “if a person’s endeavor is for his nation, that person becomes a miniature nation on his own” is not only valid for human beings.

Ants, using a different method than termites, synthesize bacteria eliminating chemicals in their saliva glands that protect them from infectious diseases. These chemical combinations are very effective against bacteria and fungi. Ants protect themselves by covering their bodies with these substances at certain intervals. Termites, although in appearance not very different from ants, do not produce antiseptic substances in their bodies. Termites use a different strategy by establishing a symbiotic relationship with the bacteria that live in their intestines. Some termites that feed on decayed wood need enzymes to digest the cellulose. The cellulose needed by termites is synthesized by the bacteria in their intestines and turned into sugar. Thus, termites receive the glucose they need for survival and bacteria are provided with a comfortable berth in the bodies of the termites. Because of this symbiotic relationship, the production of fatal antibiotics that would kill the bacteria would be harmful to the termites themselves.

Instead of producing chemical compounds or antibiotics like ants, the seismic movements and self-sacrificing behavior depicted by the termites has given scientists the idea that it may be possible to benefit from termites as an early warning system for earthquakes. This idea is reflected in the Holy Qur’an, chapter Naml (The Ant), verse 18:

Until, when they reached a valley of ants, one of the ants said: “O you ants! Get into your dwellings lest Solomon and his army crush you unawares.”

This verse shows us the sensitivity of ants to vibrations. They have organs in their feet that are sensitive to movement. For one of those ants to have been able to warn the other ants, it must either have seen or sensed the coming of Prophet Solomon’s army. As obviously an ant cannot see an army coming from a long distance, they must have felt the vibrations made by the feet of the soldiers. We know that sound waves move very fast and are strong in solid objects. Because of this, by placing an ear onto railway track one can hear the vibrations of a train from far away. Termites most likely have an organ that receives vibrations that is similar to that of ants, because if a species can produce a signal (e.g. light, sound, or vibrations) for communication, they must also have an organ that is capable of receiving this signal. Since termites communicate with vibrations, they must also have an organ that is sensitive to weak vibrations. From this respect, if the code that is based upon some of the behaviors and vibrations used by the termites can be decoded, then are techniques of predicting earthquakes can be considerably improved.

What is reality? What is illusion? Do we have free will, or is our life somehow preprogrammed? Such questions have vexed humanity from the beginning. Technology has added another wrinkle: virtual reality. Now that we can create reality, how do we know that what we consider reality is really real? Might we be in somebody elses virtual reality program?

External Reality

Nobody remembers being born. By learning about ourselves, we learn things from our surroundings and people, and how to experience events on our own. If our senses function normally, we begin to wonder about our sense-related experiences and seek meaningfulness: Who am I? How were I and the world created? Why am I here?

Each normal person is aware of himself or herself and the external world. We learn how to distinguish colors and shapes through sight and touch. But how would blindness or an impaired sense of touch alter our perception and understanding? Perhaps we would ask: Is the red that I see, the roundness that I see and touch, inside or outside of me?

No one can explain what red is. Yet we know what it is because people tell us that a ripe tomato is red, or that beaming the 620 to 740 nanometers wavelength into our eyes lets us experience redness. In both cases, someone else causes us to see red. Redness is also in the mind, for we can see it behind closed eyes. This is true for the other senses as well.

Recent brain studies reveal that neither light nor sound reaches our brain. Rather, it receives electrical stimuli produced by our senses and then processes them into meaningful sense impressions.(1) As the brain cannot distinguish between a real and an artificial electrical stimulus, we can make it see and respond to imaginary pictures as if they were real. When we see a red apple, what do we really see? What does its reality mean? Is it outside of us, are our senses tricking us, or is the world presented to us in another way?

What Is Virtual Reality?

Scientists and philosophers traditionally considered space and time absolute, as defined by Aristotle and formulized by Newton.(2) In other words, the space we inhabit existed before us and will exist after us, and time flows over and through it at a uniform rate. Modern science, particularly Einsteins theory of relativity, undermines this assumption.(3) Time and space are not absolute; they exist with us, partly because we invest them with reality and meaning. If we define real by what we feel, smell, taste, hear, and see, then real is simply electrical signals interpreted by our brain. The world may exist as part of a neural-interactive simulation, meaning that we might be living in a dream world.

Virtual reality is defined as a cartoon that we can enter; an interactive computer system so fast and intuitive that the computer disappears from our mind and leaves its generated environment as reality; and a computer-synthesized, 3-D environment in which more than one person can engage and manipulate simulated physical elements and interact with human representations or invented creatures.(4) Essentially, it is a hardware system that uses headgear, gloves, and other items to make us feel that we are in a computer program. Its core is a simulation system based on a programmed process that handles all interactions, scripted object actions, simulations of physical laws (real or imaginary), and determines the worlds status. This simulation is a discrete process that is iterated once for each time step or frame. Several systems can be coordinated to create a smooth virtual world.

Is Virtual Reality Possible?

As we are conscious beings, our senses gather data and transmit it to our brain for processing. But we cannot consider this data processing, which is a computers main task. We experience things; computers process data.

Virtual reality appears to go a step further because it creates a reality. Miniature screens in goggles, stereophonic sound in headphones, and a pressure-sensitive glove can create an illusory immersion in another 3-D space. But such informatic technologies still depend upon our sense organs to have any effect. Virtual-reality goggles display moving imagery to the retina, but that information must be transported along the optic nerve to the brains visual cortex. Only the brain can render this bio-information into conscious experience.

Theoretically, a computer can create a desired reality via an electrical stimulation of nerve fibers. The brain can be manipulated to see red by stimulating nerves in our retina, feel tension in our shoulders, and so on. Some say scientists can construct a virtual world that is just as real as the real world. Others disagree, citing two objections: the direct mind“body connection, and the necessity of simulating the entire universe.

The Direct Mind Body Connection: Pressing a finger causes a sensation in that fingera specific, visible location in 3-D spacenot in the brain or mind. But if we swing a numb leg, we feel a tingling sensation along it. This numbness and tingling is caused by a compressed nerve further up the leg, maybe in the knee, while the sensations paradoxically seem to be spread toward the foot. Apparently, the brain receives signals from a particular nerve fiber and imaginatively projects the resulting sensation back to the nerve ending. Since the brain receives only a bundle of nerve fibers bearing pulsed signals from the leg, and no information about where these signals originated, it assumes that they originated in the leg’s nerve endings and projects the sensation to that site. As the mind can be fooled, we can say that it creates a complete, subjective body image and then assigns all bodily sensations to specific locations. Do we press our physical or body-image finger? We press our body-image finger, for this is the finger recognized by the brain. Some people say that such feelings as love and toge-therness cannot be simulated. But they can, for the world we experience exists inside the mind and is projected onto the physical world. Seeing love in a spouse’s eyes is the result of light reflected from his or her eyes, focused onto our eyes’ retinas, and coded electrical signals transmitted from the eyeballs to the brain. Thus the only connection is one mediated by electrical (albeit biological) signals. Whether we have bionic or normal eyes is irrelevant, for what matters is the person behind the eyes, not the eyes’ mere visual apprehension. If a couple is immersed in virtual reality, they can still look into each others’ eyes in exactly the same manner. The same is true for togetherness and other feelings, as well as what our five senses experience. Simulating the Universe: This argument overlooks two points: First, we focus on certain things, relegating everything else to the background. Our optic nerve can be stimulated to ignore what we consider un-important. Second, as our sight and hearing are limited to a narrow spectrum of light and sound, the computer only has to focus on that particular spectrum.

An Interesting Experiment

A Ph.D. project in Manchester involves communicating with a robot located 40 miles from the lab.(6) Sensors in its hand read temperature, pressure, and humidity. When wired to a fast communication net, it sends collected data to a glove worn by an operator in the lab so that he or she can feel what the robot feels. This two-way communication system enables the operator to command the robot to move its hand and touch nearby objects by moving the glove. In one test, the hand touched a hot object and the operator’s hand felt the burn. The operator sees what the robot sees, thanks to two video cameras in the latter’s eyes.

What Would Happen If ? (7)

We can simulate a world. A normal brain stores at least 1018 bits and processes information at about 1015 bits per second.(8) Thus we can make an hour seem like a year. The subject will see changing seasons, solar and lunar movements, and lengthening and shrinking shadows. We know that our program causes these effects, but he believes cause and effect to be operative: Have you not seen how your Lord spread the shadowif He willed He could have made it still thus We have made the sun its guide (25:45). This verse indicates that the sun rises toward noon, and that shadows shrink and then begin to lengthen as the sun declines. The subject is limited by the program. For example, he appears to throw a stone, but only if the computer generates the necessary images and sensations. His action is virtual, as in: You killed them not, but God killed them. You threw them not when you threw, but God threw, that He might test the believers by a fair trial from Him (8:17). Let’s send in a virtual messenger to inform the subject of the programmer’s rules. If he does not obey, he will be punished. For example, we could easily rewrite the program to exclude sunlight. After terminating the program, the programmer could explain and demonstrate the truth of the virtual messenger’s words. The subject would have to accept the programmer’s control of, and his lack of influence upon, his life. This is a lesson for those who struggle with their perception of the physical world and the reality of the unseen spiritual world. Two Qur’anic verses show that such speculations are not so different from the subject’s virtual world: Say: Tell me, if God made night perpetual for you until the Day of Resurrection, who is a god beside God who could bring you light? Will you not then pay heed? (28:71), and: How can you reject faith in God? Seeing that you were without life and He gave you life; then He will cause you to die and will bring you again to life; and to Him you will return? (2:28)

Conclusion

For believers, such advances bring one question to mind: Are we living in a virtual world created by God? Most religions answer yes. Although their goals or understandings may differ, the main point is the same: Our life in this world is only a prelude of what is to come.

Footnotes

1. The Brain Tumor Foundation of Canada. Online at: www.oncolink.upenn.edu.
2. Online at: http://eserver.org/ philosophy and www-groups.dcs.st-and.ac.uk/history, respectively.
3. The Virtual Reality Store. Online at: www.thevrstore.com.
4. http://ksi.cpsc.ucalgary.ca.
5. Christianity, Judaism, and Islam consider this world a testing ground for the eternal life. Buddhism and Hinduism consider it an illusion that must be penetrated to achieve enlightenment.
6. Osman Kocak, Virtual Reality in Medicine (Ph.D. diss., Salford University [Manchester, UK], 1996).
7. Adapted from H. Baki, Virtual Reality (Ph.D. diss., Newcastle University [Newcastle, UK], 1997).
8. Ibid.