How does the mind arise from the brain?

The study of  comparing the neural stem cells with the meristematic cells in a cherry tree




Research notes from the Minamiohya Clinic, 2013


                                               Author :   Tetsushi Nagai






1. Foreword

2. On what grounds can we compare neural stem cells and meristematic cells ?

What is the mind? Neuroscientific approaches up to the present

         3.1 Where is the mind?

         3.2 Understanding the mind with psychology

         3.3 Understanding the mind with neuroscience

         3.4 The problems with neuroscience

4. Development of the brain and a cherry tree

         4.1 A new theory based on the existence of neural stem cells

         4.2 Neural stem cells and the meristematic cells

5. How does the mind arise from the brain?

         5.1 Conjectures based on brain development

         5.2 The relationship between form and function

         5.3 The role of time

         5.4 Self-consciousness

         5.5 Intuition

6. The development of the mind

7. Afterword





Human behaviour is controlled not only by instincts but also by the mind. However, the relation of the mind to the brain has not been fully explained. In conventional interpretations, the mind is not believed to be located at any one spot in the brain, which, if true, suggests that we will remain forever unable to explain the mind completely, regardless of our understanding of the brain’s local functions. Brain development resembles the branching process of the cherry tree, in which the trunk branches off into limbs and limbs into twigs. As a novel method of understanding the mind, we compared the patterns of neural stem cell activity with the growth patterns of meristematic cells in the cherry tree. Studying plants in the natural world enables us to keep an open mind.

Each neural stem cell ( meristematic cells in the cherry tree) in the cerebrum (the branches) changes into neurons or glial cells (the buds, flowers, and leaves) in response to information from the external environment. New tissue is added to the memory (new stems). Meanwhile, old neurons die (just as twigs that have long been in the shade will break off). Growth continues as long as life continues.

This novel perspective suggests that the mind encompasses the entire cerebrum, whose neural stem cells (meristematic cells in a cherry tree) retrieve information from both the external environment and internal memory (the tree's stem and limbs).





brain ,   cerebrum

neural stem cells

meristematic cells




neural network  

cell differentiation 



1. Foreword


Despite recent technological advances, many things about the brain remain unclear to us, such as the structures that give rise to brain function,; the activity; an brain disease; and their treatment.  Our current knowledge is merely the tip of the iceberg. Research has shown only that every part of the brain contains a great number of nerve cells (neurons), as well as supportive glial cells, with blood vessels that crisscross its surface.


Under the surface of the brain, there are hidden things that we have not even begun to understand (Masao Itō, 1998). For example, we are compretely  unable to explain how memories, thoughts, and emotions are created simply by neurons and glial cells, even if we vainly attempt to explain these process based on the phenomena of physics,  the chemical reactions that we have discovered, or even  the latest computer technology. This is because the brain comprises an uncountable number of cells, each of which has its own individual life, and is able to alter itself and divide . Biology researchers have gone all the way down to the molecular, but the relationship between the brain and mind remains unclear.


The workings of human life and the growth of a plant for example, the symbolic broad-leaved deciduous rosa multiflora sakura (hereafter referred to as ‘the cherry tree’) are comparable in that they have a common life process. That is, as living things, both have cells, that continuously differentiate into new cells. Similar to the human brain, the cherry tree has mechanisms, that allow it to recognize itself and respond to its environment. Those structures are located at the ends of the trees roots and leaf stalks and are called growth point cells. These cells actively devide, and are the points at which new tissues are created. Of course, this is not to say that a cherry blossom tree which is, of course, a plant has an organ like a brain that can react simultaneously to external stimuli and give rise to thoughts and reactions. However, through cytodifferentiation of its innumerable growth point cells, the cherry tree adjusts itself to the changing seasons, and, develop buds that grow into flowers, leaves, and branches. For a single tree, this is a marvellous achievement in terms of growth.


In recent years, cells known as neural stem cells have been discovered in the brains of human adults. These cells can be thought of as acting in a similar way to a plants meristematic cells.  They possess what is called diversity characteristics, meaning that they have the potential to become many different types of nerve cell, but have not yet undergone cell differentiation at the most detailed level. This discovery, overturned the widespread belief, that regeneration of neurons does not occur in higher animals (Gerd Kempemann, Fred H. Gage 1997). The discovery of these new neural stem cells suggests that the brain possess and operate on the same kinds of growth mechanisms.


By using simpler modes of thought that differ from previous purely neuroscientific methods, we may now be able comprehending the mind is said to be the greatest challenge left to mankind; it is also one of the most difficult in principle. We cannot expect any significant progress if we persist in clinging stubbornly to traditional scientific methods.


In this article, the growth point cells of plants and the neural stem cells of the brain are compared as a fun     for a novel theory the workings of the brain. Rather than using standard scientific methodology, we will attempt to apply an intuitive approach to the question: How does the mind arise from the brain?-




The French philosopher and mathematician Blaise Pascal (16231662) said: Man is a thinking reed. What kind of living thing did he mean by a reed? It is thought that plants neither think nor have feelings; indeed, for a plant, neither of these functions is necessary. Plants are easy to understand as living things. However, they have keenly developed senses: they cleverly adjust to changes in the natural environment, and even possess have the ability to propagate by means of cloning.


In the distant past, biologists maintainined that only plants and animals that could be seen by the naked eye should be classed as living things. However, with the invention of the microscope and other such equipment, microbes and other organisms that could not be seen with the naked eye came to be classified alongside with animals and plants under the general term of living things. What Living things differ from inanimate objects because the former have cells. The cell is the smallest unit possessed by all living things, and acts as a microscopic room for the organisms genes (DNA).


When it comes to the phenomenon of life, all living things on Earth  not just animals, but plants, amoebae, and bacteria, too  share the same basic mechanisms. In addition, they are largely the name in their basic cell structure, basic metabolic functions, genes, and even so far the decryption code of their chemical molecules are all largely the same. Thus, when comparing them as living things at the cell level, animals and plants are basically the same. One large difference between them, however, is that plants do not have to acquire energy from other animals, because plants obtain their energy from the sun. Furthermore, animals have various internal organs. Of particular interest -is the brain, which allows animals to distinguish themselves from others, control the other organs of the body, and operate as one complete organism.


The most unusual role of the human brain is that it enables us to recognize our surroundings (i.e.,self awareness). Understanding the structures of the brain is part of our work, but we believe it is absolutely vital basic knowledge for all of us. Due to the unfortunate fact that my clinic does not have the relevant specialized research facilities, we have been restricted in terms of methodology to observing the daily lives and activities of human beings, along with the cherry tree that we can see from our windows.


Since ancient times, Japanese have considered the cherry tree a symbol of their psychology as a people. Alongside us, the cherry tree changes with the seasons; first it sprouts buds, then it flowers, then bursts into full bloom, and finally sheds its leaves and remains bare throughout the winter.  The thought occurred to me that the grace, beauty, and strength of the cherry tree exhibit the very meaning of what it is to be alive after which we was possessed to ask: What is the mind?







3.1 Where is the mind?


When we awaken from sleep, all our sensory organs, our eyes, ears, and skinnaturally become aware of the world around us. In addition to this awareness, we think and recognize based on our memories of our existence in society (otherwise known as self-awareness). Until now, what we called the mind had been defined simply as the origin of all mental activity in the brain, or, alternatively, as the general term for mental activity. These vague definitions were due to the fact that the brain has no muscles; thus,, we cannot directly view mental activity with the naked eye. These invisible brain activities are indirectly based on various external stimuli, e.g., facial expressions,  behaviour, body language, and spoken language. Moreover, we also sometimes define the mind as a complicated awareness, that we can neither see nor describe in words. Sometimes, the mind is defined as the thoughts and ideas that arise seemingly of their own accord.


What is the mind? Where is it located? Human beings have asked themselves these questions since the dawn of civilization. Six thousand years ago, in Egypt,  it was believed that the heart was the seat of the mind; four thousand years ago, in Babylonia, the mind was said to be in the liver. In Ancient Greece, with the advent of more systematic scholarship, it was said that the mind was originated in the functions of the brain or heart. For example, Hippocrates (c. 460 BCE c. 377 BCE), called the father of medicine, believed that the mind was the functions of the brain,. the philosopher Plato (c. 428 BCE - c. 347 BCE) believed that the mind lies in the spinal cord, and Plato's pupil Aristotle (c. 348 BCE -c. 322 BCE), thought that the mind was to be found in the heart.


Because Aristotles ideas had a great influence on European thinking, it was long believed that the heart was the seat of the mind. However, with the birth of modern science in the 17th century, the brain once more became the focus of attention. The French philosopher René Descartes (1596 -1650) claimed that the origin of thoughts, and the mind, was in a very deep part of the brain called the pineal gland, which was connected to the nerves of the eyes, thus making it able to sense light and secrete hormones. Similar-ly, the second-century Roman physician Galen (c. 130 -c. 200), who devoted himself to anatomical research, believed that what he called the flow of the spirits was not to be found in the brain itself, but inside cerebrospinal fluid-filled channels within the interior of the brain which,  he called brain rooms


There were many other such theories, but after the 17th century, it was generally agreed that there was some relationship between the mind and brain. However, the nature of that relationship was an issue that split thought broadly into two schools. The first the monistic theory claimed that the mind and the mental activities of the brain were the same thing, and that they were just two words for the same process;  the second the dualistic theory claimed that the mind and brain were different things, different processes, and that the mind was independent from the brain.


The two theories fundamentally differed, which led to a long intellectual standoff. However, the dualistic theory was predominant because it was compatible with the principles of Christianity. As an example, in the 18th century, the French physician, Julian Offroy de la Mettrie (1709 1751), propounded a monistic mode of thought, and demonstrated that according to the principles of physiology, nothing other than the functions of the brain could be responsible for human mental activity. Upon  publication of his findings he was faced with a storm of vitriol from the Church, and was forced into exile.


Today, however, we do not have the luxury of doubting the monistic theory. We accept that what we call our mind is a function of brain activity. It is undeniable that the human brain is created from a mesh of innumerable nerve cells, and that all mental activities are spun from inside this mesh. However, regardless of where we search in the brain, there is no physical proof of this fact. Furthermore, there is still no answer to the question: ‘How does the mind arise from the brain?’



3.2 Understanding the mind with psychology


After plants put down roots into the earth, they cannot move. Instead, they must use their keen senses to adjust and adapt themselves to the seasons and environment in which they grow. We humans, however, do not simply repeat the same actions over and over in this way; we are aware of our environment, and our actions are controlled based on memories, emotions, moods,  and thoughts that come from the brain. 


Scientific research on human mental/psychological development  began in 1879, when the German physiologist and philosopher Wilhelm Wundt (1832 1920) founded the worlds first laboratory of psychological research at the University of Leipzig. However, the inner workings of the human mind are obscure, and cannot easily be measured directly or objectively; thus the science of psychology attempts to clarify these internal psychological and emotional processes by means of objective research based on quantifiable external behaviours. In psychology, which deals with the relationship between hidden mental processes and external behaviours, and  uses both experiments and observation as research methods, the word reactions is used rather than the word mind. Furthermore, psychology divides the processes of human life from birth until death into three stages the activities of the mind,  the actions born of these activities, and the human meaning that those actions have, and regars the mind as composed of many components. Due to recent developments in neuroscientific research methods we have managed to understand the relationship of some of these components to the brain itself. However, we still cannot explain the essence of the innermost component that controls the other components on a fundamental level . This innermost component has been variously referred to as the self, ego, soul, spirit or ones self, and is thought to be the quintessence of life.



3.3 Understanding the mind with neuroscience


In ancient times, it was believed that pneuma was  at the origin of all nature, human life, and all their associated workings was. This word in Greek has various meanings, including ‘breath’, ‘wind’, and ‘soul’. Pneuma was invisible to the naked eye, but its movements could be heard and felt; It connected human being to human being, and human being to nature; and its existence was credited with enabling humans to live together and achieve greatness as individuals.


In 1791, Luigi Galvani (1737 1798), an Italian anatomist and physician, discovered electricity using the leg of a frog and thus paved the way for the discovery of the neurotransmission system. The English chemist and theologian Joseph Priestley (1733 1804) developed an innovative method of experimentation. Beginning with his discovery of oxygen in air, he also separated various different gases, and eventually found that the heat within the human body was caused by chemical reactions. In 1774, Priestley visited France and explained his discovery of the constituents of air to the chemist Antoine Laurent Lavoisier (1743 1794). Lavoisier immediately realized the significance of the fact that even things that are invisible to the naked eye are made up of many different substances. This led in turn to the chemical revolution that would form the foundation of modern chemistry, and that thoroughly negated the idea of the existence of the metaphysical substance pneuma, which had been thought to be responsible for thermogenesis in the human body.


At this time, in an effort to keep up with developments in modern physiology, brain research  also entered a period of extremely significant developments. Research by the English physiologist Charles Scott Sherrington (1861 1952), revealed that transmissions between neurons were caused by electric signals, and that transmission of these electric signals was due to a chemical agent found in the connective parts between neurons (the synapses). Thus information is transferred within the brain via two types of transmission system: chemical and electrical. The discovery of this information transmission circuit, which is known as a neural circuit or neural network, provided a stepping stone for continuing efforts to understand brain structure.


After the Second World War, W. Penfield (1891 1976), a Canadian neurologist and neurosurgeon who had studied under Sherrington, put into practice the contemporaneously formulated theory of the localization of brain function, which was based on the idea of electrical stimulation of the cerebral cortex during brain surgery. After obtaining the patients advance consent, he attached electrodes to various regions of the cerebral cortex, applied electrical stimulation, and observed the patients responses. The results he observed when he applied the stimulus to the region of the brain  just above the ear, had a decisive impact on neuroscience as a whole:. Penfields experiment effectively proved the localization theory. However, despite the fact that he had proved that brain function was localized, Penfield concluded that The mind is not inside the brain it is located elsewhere.


In 1958, D.H. Hubel (1926 ) and T.N. Wiesel (1924 ) discovered the optic nerve cells, which respond only to specific stimuli and specific conditions.  This discovery set the precedent for the various hypotheses related to recognition cells,  which were put forward during the 1980s and 1990s.


When we see the image of an object, our various nerve cells respond to that image. There are currently two basic schools of thought on how we recognize an image. The first suggests that there is a specific cell in the brain designed to respond to each individual image of an object. This idea takes the localization of brain function all the way down to the individual cell level. If we were to accept this hypothesis, it would mean that we each have, for example, a specific granny cell that responds only to our grandmothers face, and, similarly, a specific grandpa cell that responds only to the face of our grandfather. The second theory is that we have cells that all selectively respond to various characteristics of shapes, i.e.,  an objects image is displayed to us via a combination of these cells. According to this idea, each image of an object is displayed to us as a combination of the objects particular characteristics; the information we receive is not necessarily localized down to the level of individual cells, and the information is displayed by a group of incomplete cells that have a number of possible responses.


From the 1970s to the 1980s, the discipline of computer science made immense advances. In parallel  with this technological progress, the idea that the mental activities of the brain were similar to the data-processing functions of a computer gradually gained strength. With advent of the computational theory of neuroscientist David Marr (1916 1998), the monistic theory of the brain became persuasive. Using as an example the fact that the information transmission circuit found in the synapses of the brain works in exactly the same way as a computer, Marr proved in theory that it was possible to explain both the brain and a computer by invoking the same system.


The existence of such an information processing system showed that the brain is constantly processing information at extremely high speeds. However,  at the same time it was recognized that the brain is an information processing system so complicated and so fast that no matter how many supercomputers one might link together, a machine did not stand a chance of keeping up. Despite this, computer science has expanded the methodology which can be applied to investigating the many questions related to the mind that are raised by those invisible brain activities. Along with increased knowledge in the fields of anatomy, electrophysiology, experimental physiology and developmental physiology, new brain activity scanning systems such as magnetic resonance imaging(MRI) and positron emission tomography(PET) were introduced during this period. These allow us visualize, via an on-screen image, the region of the brain that is responsible for recognition functions. Simulation technology, which is able to reconstruct neural networks/neural circuits and nerve systems, is also being utilized. With the use of these technologies, neuroscience research is  advancing at a rapid pace. We are getting ever closer to the crux of the monistic theory which states that the mind is to be found somewhere within the brain.



3.4  Problems with neuroscience


It is thought that the brains processing of information in the sensory mechanisms is carried out by the approximately 14 billion nerve cells that make up the cerebral cortex. Nerve cells are bound to each other at the synapses. The total number of synapses in the entire cerebral cortex is as high as 100,000 x 14 billion. These synapses combine together, creating innumerable nerve circuit meshes. The nerve cells in these meshes do not remain fixed in place like part of a machine; rather they are constantly undergoing cell division and reproducing. Thus the nerve circuit itself is also constantly changing. Although these numberless billions of nerve cells all have the same genes, the cells have  been created in different environments and at different times via cell differentiation. So, even if we regard all nerve cells and all synapses to be identical, and add them together, this still does not explain the workings of the brain as a whole. The reality is that even if we focus our efforts and manage to ultimately explain the mechanisms of one part of the brain in detail, we are still unable to explain the mind, which is the sum of  the functions of the entire brain.


Natural science aims to explore universal truths and laws, and neuroscience then applies that systematic knowledge. However, both natural science and neuroscience ultimately regard the brain as if it were something inorganic. The knowledge obtained in this manner is taken as objectively proven fact, which is then applied to every given phenomenon, no matter how limited the sphere or in what type of organism it was found to hold true initially. The prevailing belief that comprehending  every phenomenon on a basic level requires that we be able to understand and interpret it has been the dominant mode of thought since the scientific revolution. Therefore, based on this idea, scientists believe that if only we can discover new facts about the brain, these facts can be interpreted via the brain as inorganic-matter mode of thinking that has held sway until now. Basically, this mode of thought leads to the incorrect notion that the phenomenon of life and the functions of the machine, which both have living cells as their basic components, act based on the same structures. In the end, for us as human beings, the act of clarifying and understanding some given phenomenon is nothing more than an attempt to satisfy ourselves, to feel secure, or, alternatively, to replicate said phenomenon so as to make use of it in our daily lives.


With the abilities we have as human beings we must realize that just because we can understand, accept, be satisfied with, and make use of the simple and universal structures as they are, we cannot expect to understand and be able to replicate the basic structures of the phenomenon of life in the same way as we would a machine.





4.1. A new theory based on the existence of neural stem cells


There are several hundred billion nerve cells in the brain. These are made up of the meshes of electrically activated neurons and non-excitable glial cells, which help neurons function properly, and whose number is ten times greater. Unlike other normal cells, a neuron is surrounded multiple dendrites; one of those dendrites is longer than the others, and is called an axon. Neurons communicate through a structure called a synapse, which connects the neurons together. Electrical signals arising from a neuron go through the dendrites and the axons, and are sent to neighbouring neurons by chemicals in the synapse. It is thought that this network, which sends signals to the neurons through the synapses, is the brains basic cellular tissue structure (which we shall refer to as the neural network).


It used to be thought that most of the neural network, which produces the essential neural functions, was formed during foetal development and that the cells would not divide again after they were formed. It was also believed that the adult brain was larger than that of a newborn baby due to age-related increases in the number of glial cells (which are separate from neurons) and myelin, (which acts as an insulator for synapses and for electrically excitable neurons and is produced during infant development) period. Furthermore, it was thought that although tens of thousands of neurons perish every day in the adult brain, they could not be replaced. Thise textbook theory, went utterly unchallenged until relatively recently.


In 1997,  Peter S. Erikson (1936) , of Sahlgrenska University in Sweden, and Fred H. Gage (1940) ,  the Salk Institute for Biological Studies, discovered that neurons are newly created every day at least in the hippocampus, which is located in the medial temporal lobe of the brain and plays an important role in memory and learning. Furthermore, in just the last few years, the discovery of neural stem cells, which do not differentiate into the cells of the nervous system and therefore have the potential to become different types of cell, has overturned the conventional wisdom that neurons are not newly created in the brains of adult higher-order animals.


As it has become clear that neurons are replaced in the adult brain, it can be further assumed that the structure of the neural network is not fixed, but rather is constantly changing. Moreover, this discovery has given rise to the hypothesis that the mind is formed by the accumulation of new information that is stored as memories.



4.2 Neural stem cells and the meristematic cells 


 Once a cherry tree has matured, it appears to have stopped growing. This is because as the tree is buffeted by winds and damaged by insects over the years, only the strong branches survive, and the number of growing point cells the cells able to produce new buds continues to decrease. However, even an old tree with a severely depleted number of meristematic cells continues every spring to produce a small number of buds ( which then bloom into flowers), puts out fresh green leaves, and thus continues to grow for as long as it lives. We can interpret this in terms of the brain by saying that although the number of neural stem cells decreases with age, the brain, just like the cherry tree, continues to put out new buds, so to speak, and continues to develop as long as it lives.


Over the years, substantial effort has been devoted to understanding the extremely complex functions of the brain. Perhaps this is because we human beings see ourselves as special organisms, and therefore believe that we must have special qualities or mechanisms. However, if we treat human beings as just one type of organism,  we can see that all living creatures including plants, animals, fungus and viruses have mechanisms in common. In other words, from birth until death, at all times, every organism recognizes its self and its non-self and possesses undifferentiated growth points. Those growth points,  which have finished differentiating,  leave traces of themselves behind as memories, and as this process is repeated, the memories one possesses as ones self change over time. It is thought that these growth points, (which are able to differentiate), and memories, (which have been created from these differentiated growth points,) are the building blocks of life. 


Through asymmetric division, neural stem cells, which are the brains growth points, grow into two different daughter cells: a new neural stem cell and a nerve cell. Because of the very large number of differentiating neural stem cells, the brain can play an important role as an organ (the neuron network structure) namely, the continuous creation of an individuals personality by means of the constant differentiation of neural stem cells into nerve cells, in combination with information gleaned from the outside environment and accumulated memories. Once these nerve cells have finished their duties, the glial cells are left as memories. In the meantime, the next group of neural stem cells begins to differentiate; thus the neuron network is constantly updated and the brain keeps developing, just like a cherry tree.


Again, this concept is easier to understand if we liken the brain to a cherry blossom tree. A cherry blossom tree growing outdoors is constantly subject to natural stimuli; it is buffeted by wind and  exposed to the sun and rain. The countless number of growth point cells in the buds on the trees branches sense light and temperature, differentiate, and put out buds, flowers, and leaves. In this way, the new branches that have grown over the years remain as memories, while new meristematic cells are produced. These growth cells gather together and eventually form a whole cherry tree, from the thick trunk to the numerous small branches growing out from it, that keeps growing. In short, both the brain and the cherry tree continuously change and develop, without limit.





5.1 Conjectures based on the development


When considering how the mind arises from the brain, it is important to understand on a basic level how the brain occurs and how it is structured. The human brain comes into existence when one fertilized egg differentiates, producing a vast number of cells. This egg has the potential to differentiate into all of our given organs. At around the middle of the third week of the prenatal period, neural stem cells appear. In the early stages of the embryonic period, after repeated cell division and propagation, stem cells of the central nerve system called neural epithelial cells form a single blind-ended tube. On the upper end of the tube grow three ampulae which will eventually turn into the brain. These three ampulae, from top to bottom, are called the prosencephalon, or forebrain; the mesencephalon, or midbrain; and rhombencephalon, or hindbrain. The forebrain develops further, growing into the telencephalon, or cerebrum, which swells out on both sides. It resembles the shape of a hemisphere, and thus is called the cerebral hemisphere. The midbrain does not develop much further, but the hindbrain further differentiates, into three sections: the pons, the cerebellum and the medulla oblongata. The pons and the cerebellum together are referred to as the hindbrain, while the medulla oblongata is known as the myelencephalon.


The basic structure of the brain in vertebrates has unchanged little throughout evolution, and,  but the greatest evidence of evolution can be seen in the development of the cerebrum. For instance, in reptiles the cerebrum exists only as an appendage of the olfactory bulb, while in mammals it is responsible for most of the functions of the central nervous system. In human beings, the cerebrum is extremely large, to the extent that it covers most of the diencephalon and the midbrain. In allometric growth studies investigating the differing brain capacity of various species, a line of continuity is apparent from mice all the way up to whales. This enables us to make conjectures regarding the evolutionary process of the central nervous system. In particular, the highly developed forebrain of human beings’ (which later differentiates into the cerebrum and diencephalon, or ‘interbrain’) is very interesting due to its large size and the functions for which it is responsible. 


The same thing can be said of a cherry blossom tree. That is, a single seed grows into a trunk, branches, foliage, and flowers, to form a tree. Of all plants, the cherry tree in particular, responds to the outside world by putting out buds, then flowers, then produces green and finally red foliage in accordance with the changing seasons and years, which is very similar to how the human cerebrum functions.



5.2 The relationship between form and function


The outside world provides stimuli that our sensory organs take in and respond to. For example, a sound stimulus is responded to by a hearing organ such as the vestibulocochlear nerve;, a light stimulus is responded to by the eyes, the retina, and the optic nerve; and the warmth produced by  light is felt by the skin. When the brain recognizes things in the outside world, as well as the various matters that arise within the mind, it recognizes both the form of the thing as it exists at that moment in time, and the functions that will arise from the changes that the form will undergo. Function is a phenomenon that is tied to changes in form. For example, our eyes recognize a cherry blossom tree as a form. Changes in this form take place so slowly that we cannot recognize these changes as functions. However, because we have a stored memory of the changes in the cherry blossom trees flowers (i.e., the fact that they are in full bloom for a very short period of time, after which they all fall to the ground), when we see the cherry blossom tree in full bloom, in an instant our brain recalls the changes it will undergo. Thus we are made aware of the transience of the life of the cherry blossoms.


Our senses of sight and touch can recognize the form and function of what we are seeing or touching; however,, sounds, smells, and flavours are invisible.; Thus the brain cannot directly recognize their form through our remaining three senses of hearing, smell, and taste. However, it can recognize their function, and finally, through those functions, the brain is able to grasp the form. This is why we are able to reproduce in our memory the forms and functions of things we have seen, sounds we have heard, or scenes or situations that have made an impression on us. Stimuli from the outside world are instantaneously converted into electrical signals at the various sensory organs throughout the body, and these signals in turn activate the respective nerve cell networks of the organs able to respond to the signal. The signal is then recognized by the nerve cell network of the brain as a whole. This influences the differentiation of nerve stem cells, and becomes a new memory. Due to this endless process, our brain can reconstruct what we are not actually seeing, hearing, tasting, or touching as if it were reality. 



5.3 The role of time


When it comes to our self-awareness, we are not aware of any changes as they happen; it is as if every moment is the same as the last. However, just like the cherry blossom tree, our brain keeps developing. A group of neural stem cells in the cerebrum continues to respond not only to changes in its environment but also to our previously extant memories, which are based on the flow of time. Therefore, time is an extremely important factor in recognizinge the flow from past to future in the huge number of memories in the mind.


A newborn baby sleeps almost all the time. When it gets hungry, it wakes up and cries, is fed milk by its mother, quietens, and goes back to sleep. A babys life consists of repeating this daily cycle of short periods of wakefulness and long periods of sleep. During this earliest period, the babys brain and sensory organs are immature; it cannot yet clearly distinguish between its self and non-self. However, after this earliest period of infancy, as the eyes and ears develop, the baby gains the ability to recognize (reconstruct) the outside world inside his or her brain, even without the input of information from the outside world. Further changes occur as the cerebral cortex rapidly develops, and the baby is now awake for longer periods of time and can better recognize its external environment (the outside world). It also begins to recognize itself (self-consciousness). Thus, with this clear division between how wakeful periods and sleep periods are used, new memories are accumulated in the brain with the passage of time, while unnecessary memories are discarded.


Recognition of the sense of being alive has at its foundation the so-called time factors of past, present, and future. In nature and society, on the other hand, there exists the time factor of history, which is based on the passing of months and years. On the basis of this factor, we recognize the four distinct seasons in Japan, through which the cherry tree proceeds in its growth cycle. Thus we see that our memories are linked to concepts of date, time, and season.



5.4 Self-consciousness


The brain, like the other organs, develops to completion in womb. Immediately after birth, the brain has no consciousness, and of course cannot recognize itself or anything else. However, with stimuli from the various sensory organs,  the brain continues to develop, and by around the age of three years, it can recognize its own existence. In short, it is able to recognize its self,,or ego, (oneself). This self is based on the new memories that the brain creates by what it takes from what is around us (the outside world) and what it obtains from thinking of intangible things (the interior world). This is what is known as self-consciousness. This process is basically no different from the process of the cherry blossom tree. Every year the cherry blossom tree puts out an abundance of buds, from which sprout twigs. Of course, not all of these new twigs remain; some are broken, cannot grow, and fall off the tree. This is how a cherry tree ages, and the tree form changes.


Self-consciousness develops when the sensory organs, located throughout the body, recognize the outside world and send information that is deemed important to the group of undifferentiated neural stem cells in the brain. This information is then compared with the fundamental memories (the self or the ego), and the brain creates new memories (the neuron network). Even with our eyes closed, we can picture an immaginary scene that appears real to us, because these neuron networks, which continue to work and develop every second, become what we could call a momentary self,  search for the old memories stored in the network, and display them in the minds eye. The cherry tree, of course, does not have a neuron network like that of the human brain. Instead, its self is its countless meristematic cells, which all differentiate and develop according to their environment.


The phenomenon of dreaming i.e., seeing images in the brain while asleep, despite the absence of information from the outside world can also be explained in this way. By combining various memories, the brain is able to create an internal scene that we think we are seeing, and compare it with previous existing memories. The act of thinking is basically making judgments based on a comparison between the world that surrounded you in the past and that which surrounds you in the present. At the time in question, we tend to always believe our judgment is correct; however, with the passage of time, we often come to reconsider our original decision. In short, we are constantly recognizing things anew. The decision we made at that time, or what we thought at that time, is accumulated in the brain as memories. It is belived that this mechanism of self-consciousness is a function of the cerebrum, which has developed enough to reproduce and recognize many versions of our self.



5.5 Intuition


An infant, even though it is not able even to talk, discriminates events around it and responds to them with intense curiosity by smiling endearingly or crying loudly. It is thought that it is during this stage that neural stem cells differentiate most actively in a persons lifetime. At this time, of course, knowledge based on scientific principles and so on is unnecessary; the infants brain develops simply via the process of intuition developing into mind, just as the cherry tree does.


Intuition is the keen and instantaneous feeling we have towards even the smallest of stimuli, without thinking deeply or imagining anything consciously. This is the most important element of the mind. Intuition is basically close to instinct, or our animal-like mind. What we take in from our intuition develops into a clearer mind that is, our own intentions, or self-consciousness when the thought process proceeds further. The difference between the intuition possessed by the brain and by the cherry tree lies in the difference in the characteristics of neural stem cells and meristematic cells. What is essential to understand is that the intuition that the brain shows regarding the changing seasons is neither inferior nor superior to the intuition displayed by meristematic cells in the cherry  tree.


There is a theory that in ancient times, before calendars existed, when the seasons were not yet clearly defined-, people managed their agricultural activities by observing cherry trees. When they saw the cherry trees in full bloom on the mountainside, they could determine when it was time to plant rice seedlings, or how much harvest they could expect in the autumn.







We are not born with a distinct self-consciousness. We are completely dependent on the person who rears us for the lifelines of nutrition, temperature regulation, protection from outside dangers, and so forth. During this early period, the mind is not yet among the brains functions. With time, the body grows; however, if an infant does not receve stimuli or information from the outside world,  the mind cannot arise spontaneously within the brain, based on things that the infant has never seen or heard. The mind develops to completion by obtaining knowledge, acquiring techniques, and learning the ability to be independent as an individual. It takes as long as twenty years for the mind to grow into that of an adult member of society.


There are some expressions frequently used in Japanese such as having a heart, having no heart and having a good heart. We can assume that these expressions come from the fact that from the birth of human society to the present day, humans have always depended on one another. In short, our minds develop on the basis of our brains memories of individuals, of society, and of nature. Indeed the mind itself is proof of a person having been raised in human society. The above expressions represent the fact that human beings have recognized that, in order for us to live in nature or in human society, we need to follow the proper rules of mutual reliance, the rules of nature, and the moral codes of human society. 


The human mind is made of inherited memories that have accumulated in the long and difficult history of human mutual dependence and of human dependence on nature. The Japanese expression o-tagai-sama (‘we are both of equal status in this regard’) symbolizes the desire to settle issues calmly, through compromise and mutual understanding. This is wisdom that has been cultivated over the history of human society it is not easily dislodged. The brain, with its huge capacity of memories, can acquire a mind unfathomably rich in wisdom, built on the basis of human

interdependence and mankinds dependence on nature. With this wisdom as a foundation, the brain not only preserves its own existence, but also keeps on learning and developing as it makes careful choices  to preserve its own existence.


In summary, the mind is not included in our genetic information. If cloning technology advances sufficiently, it would be possible to create a human in a short period of time by simply copying the genes of cells. However,  to create a copy of a human being with exactly the same mind as the source,  the copy would have to spend exactly the same length of time alive and be raised in exactly the same environment in which the source was brought up. In short, it would be impossible.





7. Afterword


Until now, we have long believed that an affluent society can be created on the basis of scientific ideas. At present, however, regardless of the how much scientific knowledge we have managed to accumulate, we are surrounded by changes in our environment the problem of ageing societies, explosive increases in the worlds population, severe disasters, and so on as well as other such unpredictable events that have created more complex and difficult problems for us to solve. If this situation continues, then distress and anxiety, worries about not being able to have a stable life, and a general feeling of despair will all undoubtedly increase because, behind the curtain of scientific advancement and scientific ideas, there are problems we have either failed to notice or have avoided discussing: those problems that cannot be explained with science.


For instance, although it is true that we now live longer, we cannot avoid ageing. The number of elderly people hospitalized for treatment of health problems and anxiety is constantly on the rise.

No means have been found to halt these fundamental changes. Life does not let us die easily. Neither science nor medicine has managed to show us a way to adapt to todays super-ageing society a phenomenon that we are experiencing for the first time as a species. They tell us nothing about how we can live a peaceful, easy life.


What we must not forget by is that there are limits to human abilities, and that humans have managed to live in nature by depending on our intuition and mind. The scientific way of thinking only focuses on the benefits to be gained through comparative research; modern science does not place great importance on dealing with difficult and/or unexpected problems. We wonder if the side effects of the issues that have been marginalized will not become more and more apparent in coming years. Furthermore, people have accepted so-called scientifically-based ideas, calling them proven facts, even though they have not confirmed them for themselves.  -Moreover, depending on their requirements, people interpret these scientifically- based ideas in different ways. This leads to the discussion branching off in multiple directions, taking on an uncontrollable life of its own.


So what does the advancement of science really mean to us? Is it absolutely necessary for human happiness? If it is necessary, then to what extent? Are we sure there arent some serious hidden disadvantages behind the initial advantages? Has the interpretation of conventional science and its direction thus far been stretched, and has now slipped into self-complacency?


To answer these questions, we believe that we need to consider in turn the following ones. What is the mind that we have been given?  How can we fulfill the mind?  What did our ancestors think about the difficult problems of life, and how did they overcome them?  We must each as individuals also recognize the problems caused we have caused in nature, and society, and not be afraid to express them. If we live without fearing failure, recognizing our own individuality in the midst of the workings of nature, and recognizing the role we have to play, then perhaps we can eventually achieve happiness.


When we see patients in our consultation room, we realize that for human beings not only the symptoms of the body, also but the condition of the mind that lies behind those symptoms, is important. If we can help someone to lead, in his or her own way, a principled, enjoyable life by helping that person to understand the questions,: What is the mind?, What is the self ?, How does the mind arise from the brain ?, and Why is the mind necessary ?, then we would feel very privileged.







             南大谷クリニック 研究紀要 2013       著者 永井哲志






3.心とは? ―― これまでの脳科学によるアプローチ

 3.1 心はどこにあるのか?

 3.2 心理学による心の解明

 3.3 脳科学による心の解明

 3.4 脳科学の問題点


 4.1 神経幹細胞の存在による新理論

 4.2 脳の神経幹細胞と桜の生長点細胞


 5.1 −脳の発生過程からの推測−

 5.2 形態と機能

 5.3 時間の役割

 5.4 自己意識

 5.5 直観














 brain   大脳 cerebrum

神経幹細胞  neural stem cells

生長点細胞  meristematic cells

記憶 memory

自己意識 self-consciousness

直観  intuition

ニューラルネットワーク  neural network  

細胞分化 cell differentiation





 人間の生命の営みと、植物例えばその象徴的な桜の木「バラ科バラ属の落葉広葉樹林であるサクラ」(以下、桜と呼ぶ)の成長には、同じ生物として「細胞から細胞へ分化し続ける」という共通する生命現象が存在する.桜にも自己を認識し環境の変化に対応できる、脳と似た仕組みがある.それは根や茎の先端にあって、活発に細胞分裂を行い、新しい組織を作るもとになる「生長点細胞」である.植物である桜には、外界の刺激に対して同時に相反する思考や反応を生み出す脳のような器官は認められないが、この無数の「生長点細胞」の分化によって、移り行く季節に合わせて、つぼみから花や葉、枝へと、1 本の木としてみごとな成長を遂げていく.

 近年、大人の脳の中にも、植物の生長点細胞と同じような働きをすると考えられる神経系に属する各種の細胞になることはできるがまだ細かく分化を遂げていない「多様性」をもつ「神経幹細胞」が見つかったことによって、「高等動物の成体の脳ではニューロンの新生は起きない」というかつての常識が覆されてしまった(Gerd Kempemann、Fred H.Gage 1997).この新たな「神経幹細胞」の発見は、脳も植物と同じような成長の仕組みで活動している可能性を示唆している.これは、これまでの脳科学的手法とは違った素朴な思考からも、複雑で難解とされてきた脳の働きの解明が可能になったことを意味している.心の理解は人類に残された最大の課題といわれているが、原理的にも最も困難な課題の1つであり、従来の科学的な手法に固執しているだけでは大きな進歩は望めない.本論文は、脳の働きの説明にこれまでは用いられなかった植物の「生長点細胞」と脳の「神経幹細胞」とを対比した理論を用いて、「どのようにして脳から心が生まれるのか?」について直観的に考察した.










3.1 心はどこにあるか?



 「心とは何か? どこにあるのか?」という疑問は、文明の発祥以来、人間になげかけられてきたものである.6千年前のエジプトでは、「心の座は心臓にある」という考えが生まれていたし、4千年前のバビロニアでは「肝臓にある」とされていた.より体系的な学問が芽生えたギリシャ時代には、「脳または心臓の働き」が心を生むとされた.

 たとえば、医学の祖とされるヒッポクラテス(Hippocrates 前460?〜377?)は、心は「脳の営み」だと考えていたし、哲学者プラトン(Platon 前428 頃〜347 頃?)は「脳と脊髄にある」と唱えていた.一方、プラトンの弟子であるアリストテレス(Aristoteles 前348〜前322)は、「心は心臓にある」と考えた.

 アリストテレスの思想はヨーロッパでは大きな影響力を持ち続けたので、長い間「心臓が心の座」と考えられてきた.ところが、17 世紀に現代科学の方法論が生まれると、「脳」がふたたび注目されるようになった.たとえばフランスの哲学者ルネ・デカルト(Ren?Descartes 1956〜1650)は、心や意思の源は、「脳」、なかでもその奥深くにあって「目の神経とつながって光を感じ、ホルモンを分泌する松果体」に存在すると主張した.また、2世紀に活躍した古代ローマの医師ガレノス(Galenos 130 頃〜200 頃?)は解剖学の研究に努力して、「精神の働き」は脳の実質に在るのではなく、「脳屋」という脳の内部の「脳脊髄液のたまっている空間にある」と考えた.

 その他にもいろいろな考えがあったが、17 世紀以降は、「心は脳と関係がある」という点では大差がなくなった.違いがあったのは、その「関係」についての考え方で、大きく分けて一元論と二元論の2 つがあった.一元論では、「心は脳の活動と同じもの」であり、同じ過程を別の言葉で表したにすぎない.一方、二元論は、「心」と「脳」は別のもの、別の過程であって、「心は脳から独立している」という考えだった.

 これらの考え方はまさに根底から異なっていたので、長い間対立が続いた.優勢だったのは二元論で、これは二元論が宗教、とりわけキリスト教の説く考えと矛盾しないためだった.実際、18 世紀に一元論的な考え方を表明したフランスの医師デラメトリ(Julien Offroy de La Mettrie 1709〜1751)は、主として生理学の力を借りて、人間の精神活動は脳という物質の働きにほかならぬことを論証したが、それが発表されると宗教界に激しい憎悪の嵐がまきおこり、亡命を余儀なくされた.



3.2 心理学による心の解明




1879 年にドイツの生理学者・哲学者ブント(Wihelm Wundt 1832〜1920)が

ライプツィヒ大学にはじめて心理学教室を創設したときにはじまる.しかし、内面的世界で生じるさまざまな現象は漠然としていて、直接、客観的に測定することは難しい.そこで心理学では、客観的に、外から測定できる行動の研究を通して、内面の心理的精神的な過程を明らかにしようとする.学習、記憶、知覚、認知といった行動について、内に潜む心的過程と外に現れる行動との関連性について考えるとともに、実験や観察といった方法で研究している心理学では「心」を使わず、「反応」という言葉を使う.そして、人間の誕生から死にいたる生涯全体に及ぶ生の営みを、心の働き、その行動へのあらわれ、そしてそれがもつ人間的意味という3つの面からとらえようとして、心を多くの成分に分けて考えたが、近年、そのうちいくつかの成分については、脳との関連が脳科学による研究法の発展により明確になった.だからといって、その数々の成分を根底でつかさどっている中心の成分、生命を与えている根源そのものと考えられていた「自我(self)(ego)」または「魂(a soul)(spirit)」、あるいは「自分自身(my self)」とは何であるかは、やはり説明できてない.


3.3 脳科学による心の解明



 1791 年、ドイツの解剖学者・医師ガルヴァ−ニ(Luigi Galvani 1737〜1798)がカエルの脚を使って動物電気を発見し、神経伝達機構の究明の道を開いた.また、イギリスの化学者・神学者プリ−ストリ−(Joseph Priestley 1733〜1804)らは、革新的な実験法を開発し、空気中の酸素の発見をはじめ、さまざまな気体を分離するとともに、体内の熱は化学反応によって生じることを発見した.1774 年、プリ−ストリ−はフランスを訪れ、空気の成分を発見したことをフランスの化学者ラヴォアジェ(Antoine Laurent Lavoisier 1743〜1794)に説明した.ラヴォアジェはただちに、目に見えないようなものでもさまざまな物質で構成されていることの重要性を発見し、近代化学の確立につながる化学革命へのきっかけとなったのである.体内の熱発生の要因とされていた霊的存在、プネウマはこの化学革命によって、完全に否定されることになった.

 脳の研究もこのときを境にして、近代生理学の形成期と足並みをそろえるように、大発展期を迎えるのである.イギリスの生理学者シェリントン(Charles Scott Scherrington 1861〜1952)らの研究によって、ニュ−ロン部分では電気信号による伝達が行なわれ、ニュ−ロンとニュ−ロンの間にある接合部(シナプス部分)では、化学物質による信号伝達が起こるということが解明された.これは電気系と化学系という2種類の伝達機構を使用することによって情報を伝える、「情報伝達回路」(ニュ−ロンネットワ−クまたは神経回路と呼ぶ)としての脳の構造解明への足がかりを与えることになった.

 第2次大戦後、シェリントンの下で学んだカナダの神経学者で脳外科医のペンフィ−ルド(W.Penfield 1891〜1976)は、脳手術にさいして大脳皮質の電気刺激に基づいた新たな「機能的局在論」を実質的に施行した際、患者の同意を得て大脳皮質の様々な部位に電極を刺し、電気刺激を与えて、その時の患者の様子を観察した.その結果、患者の頭の側面、耳の上のあたりにある領域は、脳科学に決定的な影響をもたらした.いわゆる「脳の局在説」という考えがその実験によって証明されたからである.


1958 年ヒュ−ベル(D. H. Hubel 1926〜)とウィ−ゼル(T. N. Wiesel 1924

〜)によって発見された、特定の刺激と特定の状況にのみ反応する視覚神経細胞の存在は、やがて80年代、90年代にさまざまな認識細胞の仮説を生む先べんとなった.物体像が視覚的に提示されると、私たちの脳にはそれぞれの物体像に対応した神経細胞の活動が起こる.その物体像の認識にいては、現在、大きく分けて2つの考え方がある.1つは、個々の物体像そのものに対応している特定の神経細胞があるという考え方である.機能局在を1 個の細胞レベルまで押し進めようとする立場である.この考え方に従うと、おばあさんの顔にのみ反応する「おばあさん細胞」が、おじいさんの顔にのみ反応する「おじいさん細胞」があるということになる.もう1つは、さまざまな図形特徴に対してそれぞれ選択的な細胞があり、これらの細胞の組み合わせによって個々の物体像が表現されているという考え方である.この考え方によると、それぞれの物体像は、その物体に含まれる図形特徴の組み合わせによって表現されることになる、情報表現は1 個の細胞のレベルまで必ずしも局在せず、複数の選択性の不完全な細胞の集合によって認識対象が表現されているとする立場である.

 1970 年から80 年代にかけては、コンピュ−タ−科学が爆発的な進歩を遂げた.その進歩と呼応するように、脳の精神活動とコンピュ−タ−の情報処理の仕組みを同じように考えることが次第に強くなってきた.この脳の一元論は、認知科学者デイビット・マ−(David Marr 1916〜1998)の計算理論の登場によって決定的になる.マ−は、シナプスの情報伝達回路がコンピュ−タ−とまったく同じ働きをするという例を参考に、脳とコンピュ−タ−は同じ仕組みで説明できる可能性があるということを理論面から裏づけた.



3.4 脳科学の問題点


 脳の感覚過程における情報処理は、大脳皮質を構成する約140 億の神経細胞の活動によって行なわれているとされる.神経細胞は、それぞれシナプスで他神経細胞と結合しているが、大脳皮質全体のシナプスの総数は10 万×140 億個に達する.この超天文学的な数のシナプスが複合しながら無数の神経回路網を作っているのである.そして神経細胞は機械の部品のように固定されているのではなく、刻々と細胞分裂によって新しく生まれ変わっているので、神経回路も常に変化している.また、これら無数の神経細胞はみな同じ遺伝子をもっているが、それぞれ違った環境と時間で分化してでき上がっているので、神経細胞とシナプスをみな同じ単位とみなして積み上げても、脳全体の働きを説明することにはならない.したがって、どんなに努力して、ある1部位の詳細なメカニズムを解明しても、脳全体の機能である心を明らかにすることはできないというのが現実なのである.






4.1 神経幹細胞の存在による新理論


 人間の脳全体では数1000 億個以上の神経細胞があるとされ、その細胞の構築は電気的に興奮するニュ−ロンと、ニュ−ロンの活動、維持を助ける働きをしているその10 倍もの数の非興奮性細胞であるグリア細胞との網の目からなる.ニュ−ロンは普通の細胞とは違い、周囲から神経突起というものが多数伸びている.そのうちの一本は特に長く、軸索と呼ばれている.そして、ニュ−ロン同士の間をつなぐシナプスと呼ばれる構造で互いに連絡しあっていて、ニュ−ロンに発生する電気的信号は軸索や神経突起を通り、シナプスの化学物質を介して隣のニュ−ロンへ伝えられる.このシナプスを介するニューロンへの信号伝達網が、「脳の細胞組織の基本的な構造」(以下、ニューロンネットワーク組織と呼ぶ)となっていると考えられている.


 しかし1997 年、スウェ−デンのサ−ルグレンスカ大学病院のエリクソン

(PeterS.Eriksson 1936〜)とソ−ク生物学研究所のゲ−ジ(Gage 1940〜)らは、成長を終えた大人の脳(成人の脳)でも、少なくとも記憶と学習に重要な働きをしている側頭葉の内側にある海馬においては、ニュ−ロンが日常的に新生していることを発見した.またここ数年間で、その成人の脳の中にも、神経系に属する各種の細胞に分化を遂げていない未分化で多様性(その時点でどのような細胞になるのか決まっていない)をもつ「神経幹細胞」が見つかったことにより、「高等動物の成人の脳ではニュ−ロンの新生は起きない」というかつての定説が覆されてしまった.



4.2 神経幹細胞と生長点細胞











 心は脳からどのようにして生まれるのかを考える上で、その脳の発生と構成に関する基礎的知識をもつことは大切なことである.私たちの脳は1 個の受精卵から分化して膨大な数の細胞が形成される間に出来上がっていく.その1 個の受精卵はあらゆる臓器に分化できる能力があり、受精後およそ3 週目途中の

胎生期には、神経幹細胞があらわれ、胚発生の初期に脳は中枢神経系の幹細胞である神経上皮細胞が分裂と増殖を繰り返して、盲端になっている一本の管(くだ)(神経管)になる.その管の上端(頭側)の部分はやがて脳になる3 個の膨大部を生じる.これらを前から後へ前脳胞・中脳胞・菱脳胞である.前脳胞はさらに著しく発達して終脳はまた大脳となり、大きく左右に向かって膨隆し、そのおのおのが半球状を呈しているので、これを大脳半球という.中脳胞はあまり発達しないが、菱脳胞はさらに分化して橋・小脳・延髄の3 部 に分かれる.






5.2 形態と機能





 5.3 時間の役割




5.4 自己意識


 脳も他の臓器と同じように母親のお腹の中で成長して完成する.そして、出世時はまだ意識もなく、もちろん自分のことなど分からない.しかし、出生直後から様々な感覚器からの刺激で脳はさらに成長して3歳ごろ自分の存在を知ることになる.つまり「自我(self)(ego)」、あるいは「自分自身(my self)」を感じるようになる.その自分を基に、身の周り(外界)と実際にないものを思い浮かべること(内界)から感じ取ることができるすべての物事が脳の中で新たな記憶となって形成されていく.それが「自己意識」でる.






5.5 直観




















 私たちにとって科学の進歩とは何か? 人間の幸福にとってどうしても必要

なのか? どこまで必要なのか? メリットの裏に深刻なデメリットが隠されてないか? これまでの科学の考え方、方向性はそれ自体が拡大解釈されて、自己満足に陥ってしまってはいないか?

 この疑問に答えるには、「私たち人間に与えられた心とは何か?」、「心を満たしてくれるものは何か?」、「先人たちは一生の難題をどのように考えてどのような心で乗り越えてきたのか?」などをよく考察し、一人ひとりが自然の中の自分自身と社会の問題点(困っていること)を正直に捉え、素直に表現する必要があるのではないか? 失敗を恐れず自然の営みの中で自分の個性を知り、自分の役割を考えながら生きていけば、やがては幸せを感じるのではないか?











南大谷诊所 研究摘要 2013






3.心是什么 ―― 至今的脑科学研究方法


3.2 基于心理学的心的解释

3.3 基于脑科学的心的解释

3.4 脑科学存在的问题


4.1 基于神经干细胞存在的新理论

4.2 脑的神经干细胞与樱的生长点细胞


5.1 从脑的成长过程的推测

5.2 形态与机能

5.3 时间的作用

5.4 自我意识

5.5 直觉









 brain   大脳 cerebrum

神経幹細胞  neural stem cells

生長点細胞  meristematic cells

記憶 memory

自己意識 self-consciousness

直観  intuition

ニューラルネットワーク  neural network 

細胞分化 cell differentiation












1.   前言




 近年来,在成人的脑中也发现了类似于植物生长点细胞的神经干细胞,它们与植物生长点细胞功能相似,属于神经系,有产生各种细胞功能却尚未细分化,具有“多样性”。由此,“高等动物的成年的脑神经元不能再生”这种几乎被认为是常识的观点被彻底颠覆了(Gerd KempemannFred HGage 1997)。这种新型“神经干细胞”的发现,暗示了脑也和植物一样通过相同的成长结构,产生活动的可能性。


2.   为什么将动物与植物比较?




3.   心是什么?−至今的脑科学研究方法





例如,被称为医学的始祖的希波克拉提斯(Hippocrates 公元前460?〜公元前377?)曾认为心是“脑的经营者”,哲学家柏拉图(Platon公元前428左右〜公元前347左右?)曾传唱心“存在于脑和骨髓”。另一方面,柏拉图的弟子亚里士多コ(Aristoteles 公元前348〜公元前322)则曾认为心存在于心脏。

因为亚里士多コ的思想在欧洲有很长一段时间产生着巨大的影响,所以在那段时间普遍认为心脏是心存在的场所。但是,随着17世纪现代科学的方法论的产生,脑再次引起人们的关注。例如法国的哲学家笛卡尔(Renè Descartes 19561650)认为,心或意识的源头在于脑的内部深处的“与感知光的视觉神经相连,分泌荷尔蒙的脑垂体”。另外,活跃于2世纪的古罗马医师盖伦(Galenos 约130200左右?)致力于解剖学的研究,认为“精神活动”不在脑的实体里,而是在于脑的内部积满脑脊髓液叫做“脑质”的地方。


这两种说法从根本上就完全不同,所以对立了很长一段时间。但是二元论占有着优势,这是因为二元论与宗教,尤其是伊斯兰教的说法相符。实际上,18世纪主张一元论的法国医师拉美特利(Julien Offroy de La Mettrie  17091751)曾主要借助于生理学的力量,论证了人类的精神活动就是脑这种物质的活动。但由于发表这种言论与宗教界产生了激烈的冲突,引起了宗教界的憎恨,最终被迫害致死。




这种人类的内在的心里及精神上的产生过程的科学研究史是从1879年,コ国生理学家、哲学家冯特(Wihelm Wundt 18321920)首先在莱比锡大学创立的心理学教室开始的。但是内在世界产生的各种现象都是模糊不清的,很难直接或客观的进行测定。于是在心理学上,通过研究客观的外界可测的行动来了解内在的心理上、精神上的过程。关于学习、记忆、知觉、认识等活动,对内部潜在的心的活动过程与外在的活动的关联性进行思考的同时,用实验和观察的方法进行研究。这种心理学不用“心这个词,而是用“反应”这个词。而且,从心的活动,这些活动的表现,以及拥有这些的人类的意识这三个方面来捕捉人类从出生到死亡的整个生涯以及行为的话,有人曾试图将心分为多个成分,而且近年来,随着脑科学研究方法的发展,更明确了与脑的关系。虽说如此,从根本上掌管着众多成分的中心成分以及被认为给予生命的根源的“自我”(selfego)或者说“魂”(a soul,spirit),究竟是什么东西,终究不能解释。

3.3 基于脑科学的心的解释


1791年,コ国的解剖学家、医师伽伐尼(Luigi Galvani 17371798)使用青蛙的脚发现了动物电位,开拓了神经传导结构研究的道路。另外,英国的化学家,神学家约瑟夫·普利斯特利(Joseph Priestley 17331804)等人,开发了革新性的实验方法,率先发现了空气中的氧气,并在分离各种气体的同时,发现了体热是由身体的化学反应产生的。1774年,约瑟夫·普利斯特利造访法国,向法国化学家拉瓦锡(Antoine Laurent Lavoisier 17431794)说明了发现了空气成分的事。拉瓦锡立即发现了即便是看不见的东西也是由各种物质组成的理论的重要性,成为了确立近代化学的化学革命的契机。体热的产生的主要原因也是灵的存在的理论,随着这场化学革命的产生,被完全的否定了。脑的研究也以此时为界,近代生理学的形成以整齐的步伐,迎来了大发展。

 根据英国的生理学家谢灵顿(Charles Scott Sherrington 18611952)的研究表明,神经元部分是由电信号传达信息,神经元与神经元之间的结合部分(突起)是通过化学物质来传达信号的。这使用了电气类与化学类两种传达机构来传达信号,作为“信号传递回路”(称为神经元·网络,或神经回路),成为了解释脑结构的基础。

第二次世界大战后,在谢灵顿手下学习的加拿大神经学者、脑外科医生潘菲尔コ(W.Penfield 18911976),在实际实施基于大脑皮质电刺激的新型“机能局部存在理论”的脑手术时,经过患者的同意,在大脑皮层的各个部分插入电极,给予了电刺激,并同时观察了患者的样子。结果表明,患者的脑侧面,耳上方的部分领域,对脑科学有着决定性影响。也就是说“脑的局部存在论”的说法通过这个实验得到了证明。


1958年,休伯尔(D. H. Hubel 1926)与威赛尔(T. N. Wiesel  1924〜)发现的只对特定刺激与特定状况产生反应的神经细胞存在的理论终究成为了八九十年代各种认识细胞的假说的先锋。物体的像被提示为视觉时,我们的脑会产生对应各种物体像的神经细胞的活动。现在对于这种物体像的认识,大体分为两种观点。一种是存在能对应各个物体像的特定神经细胞。就是在一个细胞的水平上推动局部机能的观点。按照这种观点,会变成存在只对老奶奶的脸产生反应的“老奶奶细胞”,和只对老爷爷的脸产生反应的“老爷爷细胞”的说法。另一种观点是存在对应各种形状特征的不同的选择性细胞,通过对这些细胞的组合来表现各个物体的像。按照这种观点,认为各种物体的像是通过对物体包含的形状,特征的组合表现出来的。就是信息表现并不一定局限于一个细胞的水平,通过多个选择性的不完全的细胞的组合来表现认识对象的观点。

脑的一元论的说法随着认知科学家大卫・马(David Marr 19161998)的计算理论的登场有了决定性的地位。马参考神经节的信息传递回路与计算机的运行方式完全相同的例子,为脑可以用与计算机相同的结构来说明的说法奠定了理论的基础。


3.4 脑科学存在的问题

对脑的感觉过程的信号处理,是通过构成大脑皮质的约140亿个神经细胞的活动进行的。神经细胞通过各自的神经节与其他细胞相结合,大脑皮质的神经节的总数多达10万×140 亿个,这些超天文数字个神经节通过复合形成神经回路网。而且,神经细胞并不是像机械部件那样被固定住,而是时时刻刻都在分裂进行细胞更新,所以神经回路也在不断的变化。另外,这些无数的神经细胞虽然都存在相同的遗传基因,但因在不同的环境和时间分化产生,所以即使这些神经细胞和神经节由相同的单位构成,也不能由此说明脑的整体的运转情况。因此,无论如何努力弄清脑的某一部分的详细结构,也不能明确说明脑全体的机能--心。



4.   脑和樱的生长




  但是在1997年,瑞典的Sahlgrenska医科大学的埃里克松(PeterS.Eriksson 1936〜)和索尔克生物研究所的盖奇(Gage 1940〜)等人发现即使是成人的脑,至少负责学习和记忆的重要工作的侧脑叶内侧的海马神经元,在平时也会再生。近几年间,随着在成人脑的属于神经系的各种细胞中,尚未分化的具有“多样性”(当时尚未决定分化成哪种细胞)的神经干细胞的发现,彻底颠覆了“高等动物的脑中神经元不能再生”的说法。







5.   心是如何产生的?





5.2  形态与机能




5.3 时间的作用





脑和其他器官一样都是从母体的腹中成长形成的。而出世的时候还没有意识,连自己都还不懂。但是出生之后,通过各种感觉器官接受的刺激,脑继续成长,到三岁的时候便可以意识到自己的存在。也就是变得可以认识 “自(self))我(egoself)”或 “自身(myself)”。基于自身,感受自身周围的和想象出的事物,形成记忆。这就是“自我意识”。




5.5 直觉





6.   心的成长过程





7.   结束语