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Philosophy: Neurology: Astronomy: An Essay on Continuity and an
Awareness of Realities: Responsibilities of Science By Tetsuo Kaneko Technical Adviser Chiba-ken, Japan Vacuum is not simply empty. It is the source of everything, i.e., the
source of the universe. In the present,
this is an important image being the nearest to the reality of vacuum. All the objects of which no one is aware are
always equivalent to nothing. No one can
count how many realities of objects of which no one is aware exist. Thus, an awareness of how we can be aware
must always be necessary for enlarging awareness. Although humans (Homo sapiens) have not
needed to be aware of any realities of the Earth and have been allowed to simply
obey human DNA for 0.15 million years, now, enlarging an awareness of its
realities is inevitable for continuous future of Homo sapiens. In the current global society, there are so many
issues that cannot be easily resolved by working neuronal network systems,
which are formed Real objects that correspond to images controlling
consciousness do not exist in the neural tissues constituting the brain. In order to continue to enjoy our
civilization, cerebral activity must contribute to creating suitable images
being the nearest to realities of the objects.
Dinosaurs were capable of continuing to live on the Earth for 0.15
billion years while simply obeying their DNA.
Humans (Homo sapiens) are capable of continuing to enjoy the
civilization, while making the brain work independently of primitive images
created by fundamental neural tissues originated a priori by human DNA. While
becoming free from the will to try to avoid respecting a universal meaning that
the second law of thermodynamics holds, the brain is capable of thinking about
the dynamics of mind and a hopeful direction of the evolution of its
dynamics. While the brain is becoming
free from cerebral functions characterized structurally by human DNA, the brain
is capable of working neuronal network systems in an evolutionary manner aided
by the growth of neurons. While utilizing
the brain evolutionarily with accompanying nonlinear responses of neuronal network
systems, we are capable of finding suitable ways to continue to enjoy our
civilization. A characteristic thinking that is produced as an
output by neuronal network systems preserving the present connections must
correspond to a linear response permitted by the neuronal network systems. Neuronal networks can be allowed to change by
the aid of a specific function of nerve cells, i.e., they have a freedom to
change. An output produced by neuronal
network systems involving modification of neuronal networks is different from
an output produced without the modification.
The output produced accompanying the modification can be characterized
as a nonlinear response. Continuing to have an interest in knowing images
being the nearest to the realities of objects raises potentialities for finding
more suitable images. Continuing to find
more suitable images can correspond to continuing to modify neuronal
networks. Efforts to continue finding
them raise the possibility of forming neuronal networks contributing to finding
something new that enables any difficulties to be overcome, and these efforts
contribute to protecting the equality between the current generation and far
future generations. Efforts to find a
way to make the planetary environment and the planetary ecological system
harmonize with extremely advanced technological civilization and a way to
continue to live while avoiding unpleasant nonlinear responses of the planetary
system to human behavior must be aided by efforts to recognize Potentiality of Neuronal Growth When new ideas and new consciousnesses are needed
for resolving encountered issues, we must not deny that new neuronal networks
are necessary for doing something that the present neuronal networks are not
capable of doing. Certainly, nerve growth factor -- which is a
small secreted protein molecule synthesized in each nerve cell -- causes axonal
growth and causes axonal branching, so that nerve cells can additionally
connect with each other through axons.
Brain-derived neurotrophic factor -- which is a protein molecule -- can
also cause growth, and it has activity in the hippocampus, cortex, cerebellum,
and basal forebrain that corresponds to areas vital to learning, memory, and
higher thinking. The function of these
growth factors helps to form neuronal networks including new connections
between nerve cells in the brain, enabling neuronal networks to be modified. Attempts to think accompany the formation of new
connections between nerve cells, and these new neuronal connections allow
cerebral activity to produce nonlinear responses to inputs. Owing to the nonlinear responses, a
possibility of leading to any faults due to thinking cannot be neglected. However, new connections between nerve cells
are allowed to become free from cerebral activity dominated by former
connections, and raise the possibility of being aware of something new. Everyone knows that there are current scientific
activities being done for helping everyone to ask whether awareness about
extending the duration of advanced technological civilization is sufficient or
not. A specific cerebral condition in
which understanding originated by daily experiences is firmly dominated often
increases difficulties when approaching the realities. Scientific experience continues to be
accumulated toward the cerebral condition allowing awareness of all of the
unknowns on which interpretations are prevented from being made. Philosophical
efforts continue to be made for becoming aware of the relationships between all
the thinking matters and for encouraging everyone to become aware of these
relationships. The consequences coming
from both the scientific activities and the philosophical efforts must
correspond to two bases aiding the attempt to continue to enjoy our
civilization. The accumulation of the
consequences and improvement in the consequences must proceed while being linked
with the current existence of everyone and the current situation of everything
on the planet. Moreover, what everyone
shares the consequences helps have an opportunity to stimulate nerve cells to
grow, thus allowing us to continue to enjoy our civilization and the world
around us. Sharing the consequences allows
freedom to be given to cerebral activity dominated by daily experiences, thus
aiding the consciousness that allows daily experiences to become
objective. Advanced Technological Civilization In general, consciousness has a tendency to be
easily subjected to the expectation that both the predicted attractive effects
occurring from the use of various materials and devices and the predicted
advantages accompanied by the use of advanced technical treatments remain
allowable and meaningful. It is not rare
to encounter a situation where consciousness is simply focused on the
expectation that unexpected effects appearing as nonlinear responses to
attempts to induce the predicted attractive effects and the predicted
advantages are negligible. Despite this
fact, examples of unexpected effects that have occurred as unpleasant nonlinear
responses so far are not negligible. The possibility that nonlinear responses remaining
unknown are induced is not negligible, so that attempts to confirm the
acceptability, i.e., the reason that materials and technical treatments are
acceptable for use should be continued.
Then, the acceptability should be found as an appropriate situation
where the use of the materials and the use of the technical treatments continue
to allow the healthy human condition to be preserved with the ecological
condition. Hence, confirming the
acceptability must be linked with recognizing the realities of the Earth
involving the ecological system, and it involves attempts to recognize the
psychological or subjective reason and the scientific or objective reason that
persuade the materials and the technical treatments to remain acceptable for
being used. Confirming these reasons
must depend on both efforts that are made by science for revealing the realities
and other efforts that are made philosophically for considering the meanings of
the realities linked with currently human consciousness. A role for deeply understanding unknown phenomena
occurring as unexpected nonlinear responses to the use of technology must be
played by science, which must continue to make efforts to repeat corrections
for being allowed to become quantitative.
Certainly, a role for revealing influential phenomena that everyone
neglects unconsciously or consciously should be played by science. Consequences coming from executing the role
must contribute to suitably developing either ethics or philosophy for
maintaining our civilization. The act of
understanding unexpected nonlinear responses is linked with deepening thinking
on the continuation of the civilization.
The use of technology, to which scientific
consequences are applied, itself often make us encounter a situation where
consciousness and ways of thinking should be changed reasonably. Unless predictions based on scientific
activities have potentialities for helping to develop ways of recognizing and
for helping to change ways of thinking, the scientific activities cannot become
valuable for helping the continuation of civilization. Unless science makes efforts to reveal
realities corresponding to unknowns of which no one is aware, the meaning of
scientific activities will gradually become feeble. Assuring the continuation of civilization must be
more important than encouraging the continuous civilization to be
utilized. Thus, unless science
contributes to the civilization’s continuance, scientific activities and
scientific consequences will, in the end, be meaningless. Unless science contributes to people who make
efforts to develop human consciousness for minimizing additional entropy
dependent on unexpected and unpleasant nonlinear responses to the use of
technology, scientific activities and scientific consequences will not be respected.
NASA’s SETI project is designed to detect traces of
living creatures that have established technological civilizations on planets
located far from our solar system. According to NASA, candidates of planets and
confirmed planets, which the Kepler space telescope has detected so far, are
more than 5600. The observations of the
Kepler and the other observations show that approximately fifty of confirmed
planets and a few hundred planet candidates have their orbits within the
habitable zone. In the whole of the Milky
Way galaxy, the number of planets that may have environments allowing creatures
to live is estimated at more than ten billion.
This is an expected value estimated from observational data. Despite this fact, any signals demonstrating
the existence of living creatures that have advanced technology have never been
received so far. The Drake equation
indicates that the probability of detecting a trace of living creatures is
proportional to the number of planets having environments similar to the
Earth’s environment and also is proportional to the lifetime of an advanced
technological civilization. The current
situation where no signals have been received makes us wonder if the lifetime
of advanced technological civilization is too short in relation to the SETI
project. Science persuades several
billion human brains to become interested in consequences resulting from SETI
in order to confirm what is a currently reasonably essential aim of civilization
and the meaning of that: What is the aim that is perceived deductively or
inductively through the whole of the existence belonging to the Earth? Potentialities of Cerebral Activity Against Encountering
Limited Conditions Present neuronal networks preserve memories that are
accumulated through daily experiences. The memories help ways of thinking, which
result in recognition remaining in a category characterized by the daily
experiences. As a result, the present
neuronal networks contribute to reaching common recognition. This allows the neuronal networks to cause
the necessity to resist the modification of neuronal networks that enables the
expansion of awareness, which aids the brain to understand anomalous unknowns
disagreeing with the daily experiences.
Establishing freedom of thinking from the present neuronal networks is
not easy, so that establishing this freedom should be helped by either science or
philosophy. Establishing freedom of thinking aids the ability to
criticize recognition caused a priori
by activities of the present neuronal networks, and aids in enlarging
awareness. Establishing the freedom of
thinking enables the modification of neuronal networks. Then, the cerebral condition Neuronal networks cultivated by daily experiences
persuade linear responses to input to be produced as output belonging to both
the category of knowledge accumulated through some portions of the daily
experiences and the category of sensibility cultivated through some portions of
the daily experiences. The occurrence of
rare events that do not belong to these categories must be denied, so that the
rare events must be equivalent to nothing.
Thus, the expansion of awareness is necessary. Its expansion must contribute to elongating
the lifetime of an advanced technological civilization. At the very least, scientific journalism,
science, and philosophy should contribute to the expansion. Common things that are very frequently seen in daily
life do not stimulate the understanding that something essential makes the
common things exist. The existence of
the air surrounding us Making unknowns remain equivalent to nothing can
allow images created by cerebral activity to be isolated from realities of the
unknowns. Everyone knows that there
exist roles that should be played by science and roles that should be played by
philosophy. At least a portion of their
roles is to help generate an interest in the unknowns and to help the
consciousness that allows continuing to enjoy living in this world and enjoy
living in the universe. The brain, consisting of over 100 billion nerve
cells, can allow various breakthroughs to be achieved by the aid of a great
function of nerve cells that allows new connections to be formed with each
other through axons. The industrial
civilization encourages everyone to have an interest in rapidly achieving more
advanced technological breakthroughs that deliver comfort, convenience, and
benefit to everyone. Then, it should be
inevitable to raise an interest in developing ethics in linear proportion to
the strength of an interest in achieving technological breakthroughs. Although it is not easy to develop the ethics
that help both the acceptable use of technological breakthroughs and the
development of suitable treatments for avoiding the occurrence of unexpected
nonlinear responses, it is crucial to make it possible. Certainly, the brain’s 100 billion+ nerve
cells have a potentiality that raises an interest in developing the
ethics. Even if no awareness about the
nonlinear responses can be caused by a characteristic function of neural
tissues originated by human DNA, it is possible to go beyond limitations
attributed to neuronal network systems supporting no awareness. The great function of nerve cells that allows
new connections to be formed between nerve cells can aid in going beyond it. The fact that the aid of the great function
of nerve cells contributes to the achievement of various breakthroughs encourages
everyone to continue to make efforts to go beyond the mind’s limitations and toward
advanced consciousness that allows to continue to enjoy life Ancient people lacked the ability to understand the
role of neurons participating in cerebral activity. Moreover, they had no ability to understand
what makes stars form and what makes them move. They also lacked the ability to
understand what makes stars emit light.
However, they realized the regularity of the stars’ movements in the night
sky by continuing to observe in an extremely careful way. For the attempts to understand unknowns and
anomalous phenomena that daily experiences did not aid in imagining, cerebral
activity performed by ancient people must have accompanied great
difficulties. The degree of difficulties
that were encountered for the will to continue to make the attempts to proceed
cannot be compared with the degree of difficulties encountered for the will of
the current people. Performing cerebral
activity that avoids giving up in a situation where an essentially limited
condition (without the use of a telescope or the knowledge of Newtonian mechanics) caused great
difficulties for ancient people. This
demonstrates that the brain is capable of performing cerebral activity without
giving up, no matter how difficult a situation is. Three characteristic examples mentioned below are
products of cerebral activity found in ancient civilizations: ・Precise
astronomical observations achieved by the Maya civilization, and their
prediction of the fact that the moment when the sun, Venus, and the Earth are
aligned in a straight line for the movements of the three astronomical objects
appears in a specific year corresponding to 2012 ・Techniques for
constructing huge architectural projects in the ancient Egyptian civilization ・Earthquake
engineering
established by the ancient Peruvian civilization around 4800 years ago for
protecting structures against earthquakes of up to magnitude 8.0. These are three examples suggesting attractive
cerebral activity that proceeded without giving up despite dealing with great
difficulties. Cerebral activity within essentially limited situations
encountered by ancient people encourages us to utilize the brain’s 100-billion+
neurons actively over wide ranges of neural tissues to overcome today’s
difficulties. The first step of science in the 20th
century was to understand anomalous phenomena that belonged to the category of
no awareness. Then, the fact that
suggestions obtained from Newtonian
mechanics are partially acceptable was known. However, it was crucial to make efforts to make cerebral activity become free
from the classical assumption that the Newtonian mechanics is the complete knowledge. These efforts allowed the anomalous phenomena
to be understood accurately and precisely.
Making cerebral activity become
free from the classical assumption induced the transitions from the Newtonian ways to new ways
characterized by the Theory of Relativity and Quantum Mechanics. Then, efforts both to understand the
relationships between the Newtonian
mechanics and the Theory of Relativity and to understand the
relationships between the Newtonian
mechanics and Quantum Mechanics revealed the fact that cerebral activity
can be strongly influenced by daily experiences. Even if the limitation of thinking due to
neuronal network systems cultivated by daily experiences is inevitable, the aid
of both the Theory of Relativity and Quantum Mechanics enables the evolution of
the universe from the Big Bang Theory to be recognized as a reality of the
universe revealed by observations. While
realizing that it is worthwhile to focus consciousness on great possibilities
that are accurately specified by established pieces of knowledge, the brain is
capable of perceiving that it can be worthwhile to make the consciousness
become independent of the possibilities in an attempt to enlarge
awareness. While consciousness can be concentrated
on a limited reality served by a particular object, the brain is capable of
keeping other consciousnesses that are freely interested in various realities
of infinite objects. According to current understanding, observations
reveal the fact that more than one hundred billion galaxies exist in the
observable universe and more than one hundred billion stars exist in each
galaxy. Other observations reveal the
fact that dark energy, with which the universe is filled, accelerates the expansion
of the universe. Dark matter has helped
to form stars and to form galaxies. The
brightness of each star is emitted by reactions that proceed in matter condensed
by gravitation. The matter consists of
electrons and nuclei; nuclei consist of protons and neutrons; a proton consists
of one d-quark and two u-quarks; a neutron consists of two d-quarks and one u-quark. The quarks and the
electrons gain their proper masses for a great nonlinear property of vacuum
explained as the Higgs mechanism. In
2013, the Higgs mechanism was proven experimentally; specifically, it was
proven that vacuum has a great nonlinear property. The matter constituting the sun is composed of
electrons and quarks. The matter constituting
the Earth and the matter constituting our bodies are composed of electrons and
quarks. The whole of the properties of matter
is explained by the fact that the matter consist of electrons and quarks, of which both are fermions. The reality of matter
is simple. However, accompanying
nonlinear responses allows this simplicity to cause the diversity of matter,
i.e., to cause various characteristics of matter and various behaviors of matter. An awareness of the simplicity forming the
realities of matter allows everyone to have confidence in cerebral activity for
allowing the brain to become free from the demand for an attempt to select an
interpretation made by combining several daily experiences together. This awareness allows everyone to have
confidence in cerebral activity that allows the brain to become free from
losing the will to find suitable images which are the nearest to the realities
of objects. Images obtained from approaching the reality of each
unknown object of which no one is aware present an opportunity to allow the
brain to be free from thinking dependent on images formed on the basis of daily
experiences. Approaching the reality can
even present an opportunity to obtain surprising images that allow everyone to
be amused. Moreover, images obtained from
approaching the reality stimulate interest in unknowns that allow us to know of
ourselves. Living
as Astronomical Existence If exposure to brightness being two times as much as
the current luminosity of the sun is prolonged for 30 seconds, for this period,
everyone so exposed feels anomalous brightness and anomalous warming. However, it is difficult to imagine an extremely
strong luminosity one-hundred-billion times by one-hundred-billion times that of
the current luminosity of the sun. A
trace of such strong luminosity remained visible to human eyes for
approximately 30 seconds in March 2008.
The astronomical object that emitted the strong luminosity is called
GRB080319B, and it is located at a position 7.5-billion light years away from
the Earth; this suggests that an extremely energetic event occurred 7.5-billion
years ago. Moreover, a surprised
awareness comes when reminded of the fact that distances of most stars visible
from the Earth are a few tens of light years away. GRB080319B that was observed with the naked
eye for approximately 30 seconds is extremely much farther than the visible
stars. The astronomical event that occurred at GRB080319B is
a gamma-ray burst that releases most of its
energy in gamma rays lasting only a short time. This gamma-ray burst was detected by the Swift
satellite on March 19, 2008. The gamma-ray
burst is similar to other gamma-ray bursts lasting from ten milliseconds to
several minutes., so that it has a luminous optical counterpart as well. The optical counterpart peaked at a visible
magnitude comparable to that of the dimmest naked-eye stars. Gamma-ray bursts are flashes of gamma rays and are
the brightest electromagnetic events in the universe. They are associated with extremely energetic
explosions. Gamma-ray bursts that are
completed in a short time can originate from the merger between binary neutron
stars or the merger between a neutron star and a black hole. In each merger process, attractive elements
including gold, silver, platinum, and so on are synthesized and are scattered
into the space. After each merger
process, a black hole remains. All
observed gamma-ray bursts, being extremely energetic explosions lasting a few
seconds, have originated outside the Milky Way galaxy. Moreover, extremely energetic gamma-ray burst
explosions are rare events, and the sources of most gamma-ray bursts are
billions of light years away from the Earth, being events that occurred billion
years ago. Many hard observations for revealing the structure
of the Milky Way demonstrate that the Milky Way galaxy has a spiral structure
similar to the Andromeda galaxy’s structure.
The fact that the structure of the Milky Way has spiral arms reminds us
of the fact that an extremely long period of climate change can be linked with
the structure. The Milky Way is much
more than just a silver brightness of beautiful clouds in the night sky, but is
also the existence that influences life of all creatures living on the
Earth. A scientific consequence that
harmonizes with both spiral arms of the Milky Way and climate changes over a
long period helps us realize the fact that we exist on the Earth, moving within
the Milky Way galaxy. The Earth belongs to the Solar System and is located
at a distance of 0.1496 billion km from the sun, and is moving around the sun
at a speed of 29.78 km/s. The Solar
System itself is located 27-thousand light years away from the center of the
Milky Way. The Solar System is moving at
a speed of 240km/s around the center of the Milky Way, and now, the Solar
System is moving outside of a galactic spiral arm, i.e., is located between a
galactic spiral arm and another galactic spiral arm. This movement of the Solar System allows it to
repeat a passage through each galactic spiral arm at intervals of about
143-million years. The inside of each
galactic spiral arm is an active domain where star formation activity and the
occurrence of supernova explosions are most frequently found. Such astronomical phenomena in each galactic
spiral arm can accompany the emission of cosmic rays. During the passage of the Solar System
through a galactic spiral arm, the Earth can be exposed to a higher cosmic ray
flux. The galactic cosmic ray flux
reaching the Solar System should periodically increase with each crossing of a
galactic spiral arm. The magnitude of the
galactic cosmic ray flux can be recorded by iron meteorites exposed to it
[1]. Certainly, the iron meteorites
record the increase in the galactic cosmic ray flux while crossing the galactic
spiral arms. On the other hand, a global icy epoch occurs with a
cycle of around 135 million years. This
recurrence of the global icy epoch is revealed by examining the ratio of oxygen
atoms of a mass number 18 to oxygen atoms of a mass number 16 [2]. The ratio resulted from the determination of
traces of oxygen isotopes in fossil shells over various epochs. A series of research projects has revealed
the fact that the appearance of ice ages on the Earth varies synchronously with
the appearance of cosmic ray exposure ages being recorded in iron
meteorites. A supernova can occur accompanying a high galactic
cosmic ray flux. Collision of a high
galactic cosmic ray flux with atmospheric molecules causes dust particles to be
created in the atmosphere. The dust
particles can contribute to the formation of clouds. If the Earth is covered with clouds more widely
beyond the threshold, the reflection of sunlight back into space is more
enhanced owing to the clouds. As a
result, the environment of the Earth can become colder. The increase in the galactic cosmic ray flux
witnessed during crossing the galactic spiral arms can cause a reduced
temperature, thereby facilitating the occurrences of ice ages characterized as
the maximum reduction of the mean temperature 3.5℃ [3]. The will to try consistently to connect the three
factors, i.e., the spiral structure of the Milky Way, a specific record of iron
meteorites, and oxygen isotopes’ ratio in fossil shells on the Earth is capable
of reminding us of the fact that all the creatures on the Earth live in the
Milky Way galaxy. Realizing that the
Earth exists in the Solar System, along with many other solar systems in the
Milky Way galaxy is equivalent to realizing that a continent exists with the
other continents on the Earth. The brain,
consisting of over 100 billion neurons, allows itself to be amused at being an
astronomical existence in the Milky Way, which has a diameter of
100,000–120,000 light-years and consists of 100–400 billion stars. The reality of the Milky Way galaxy is not
independent of our existence. Every human
(Homo sapiens) is an astronomical existence along with every other creature. Efforts to consistently connect the spiral
structure of the Milky Way, iron meteorites’ indication, and fossil shells’
indication lead to an astronomical awareness.
Moreover, this awareness allows us to be confident that the brain is
capable of cerebral activity proceeding toward a more harmonized and advanced
mind, while forming new connections between nerve cells through an attempt to
consistently connect various factors with each other. Cerebral Activity Accompanying Changes in Local
Blood Flows The attempt to connect the three factors with each
other encourages us to think about each issue while simultaneously considering
various subjects linked with it. Then,
widely various portions of neural tissues, in which nerve cells are
simultaneously activated, participate in cerebral activity dealing uniformly
with the different subjects. Moreover,
this simultaneous activation can transpire even though these tissues may be
located far away from each other within the brain. When cerebral activity involves more widely various
portions of neural tissues in the brain, the cerebral activity requires more
energy. For activated nerve cells, an
increase in arterial blood flow has to occur in these portions of neural
tissues. This increase can be detected
by using a technique called functional magnetic resonance imaging, i.e.,
functional MRI. The use of functional MRI makes it possible to
detect whether or not consciousness encourages nerve cells in many different
areas located far away from each other in the brain to cooperatively
participate in cerebral activity. A
technique of functional MRI allows the indirect detection of nerve cells that
are activated and are sending out impulses.
This technique enables the distribution of activated nerve cells to be
revealed over the brain. A role of science and philosophy is to assist us to
feel confident forming objectively suitable connections between more various
subjects that do not connect with each other (or connect very faintly with each
other). This role is equivalent to
aiding the formation of new connections between nerve cells in neuronal network
systems. Fortunately, it is possible to
confirm a specific reality of the achievement of the role: the technique of
functional MRI enables the reality to be detected. In arterial blood flow, red blood cells containing
oxygenated hemoglobin molecules are plentiful, and in venous blood flow, red
blood cells containing deoxygenated hemoglobin molecules are plentiful. The magnetism of deoxygenated hemoglobin
molecules is paramagnetic so that an ensemble of the molecules induces
magnetization in a magnetic field. The
magnetism of oxygenated hemoglobin molecules is diamagnetic so that an ensemble
of the molecules induces virtually resistant magnetization. Thus, in a magnetic field, magnetization of a
local region depends on blood flow in capillary vessels. Within the capillary vessels in the local
region, if arterial blood flow becomes more dominant for neuronal activity than
venous blood flow, the magnetization of the local region will be reduced. Neuronal activation and cerebral blood flow in
capillary vessels are coupled. When
neurons in a small local region of a neural tissue become active and begin
sending out impulses, local blood flow coming into the active region
increases. The aid of nitric oxide
causes vascular arterial capillaries to expand, and allows the active region to
draw in more blood, and a rapid
delivery of blood to the active region is achieved. An expansion of arterial blood vessels
and a higher rate of arterial blood flow allow the amount of arterial blood
flow to become more dominant transiently within the active region. In the active region, the number of red blood
cells containing oxygenated hemoglobin molecules begins dominating the number
of red blood cells containing deoxygenated hemoglobin molecules around 2
seconds after triggering the neuronal activity.
The ratio of oxygenated hemoglobin molecules to deoxygenated hemoglobin
molecules rises to a peak at 4 to 6 seconds.
Then, the amount of oxygen carried in the active region can be more than
the amount of oxygen consumed for synthesizing adenosine triphosphate (ATP)
from glucose. Finally, the ratio of oxygenated
hemoglobin molecules to deoxygenated hemoglobin molecules falls back toward a
lower level located somewhat below the original level when the neuronal
activity stops. After sending out an impulse, a nerve cell makes its
cellular state return to the initial state, in which it is capable of
generating the next impulse; the nerve cell needs to use energy supplied with
the molecular form of ATP. In a process
corresponding to cellular respiration, i.e., the overall process of oxidizing
glucose to carbon dioxide, about 30 molecules of ATP can be produced from a
single molecule of glucose. Oxygen is
carried by oxygenated hemoglobin molecules in red blood cells. Glucose is the primary source of energy for
cerebral activity. Delivering oxygen and glucose to the active
region of the neural tissue through arterial blood flow is the inevitable
response to the neuronal activity. In
the small region where the neuronal activity is induced, a net decrease in the
number of deoxygenated hemoglobin molecules occurs transiently, and oppositely,
a net increase in the number of oxygenated hemoglobin molecules occur
transiently. Because the nucleus of each hydrogen atom is a
proton, it has the nuclear magnetic moment proportional to the spin angular
momentum of the proton; the proton spins that are attributed to the hydrogen
atoms contained in neural tissues take the orientation of the static magnetic
field applied to the neural tissues. The
proton spins have a tendency to be aligned in the direction of the magnetic
field as they accompany precessional rotation around the axis
parallel to the field. Protons in the
neural tissues can absorb energy, supplied as the electromagnetic wave having
the appropriate
resonant
frequency. Each proton, having absorbed
the energy, changes its spin state from the lower energy level to the upper
energy level. Each proton occupying the
spin state of the upper energy level can emit an electromagnetic wave as a
radio frequency
signal, which is measured by a receiver coil.
According to the functional MRI concept, radio frequency
signals emitted by protons occupying the spin state of the upper energy level
are measured after the energy supply is stopped, but before the emissions from
the protons are completely decayed. The magnetic field applied by an MRI scanner is
weakened in a microscopic area surrounding each deoxygenated hemoglobin
molecule owing to the magnetic property of the molecule. In each local region of neural tissue containing
more deoxygenated hemoglobin molecules, the above effect causes the emission
from protons to be weakened faster.
Hence, fewer radio frequency
signals are emitted from each portion of neural tissue where deoxygenated
hemoglobin molecules in the blood are plentiful. In contrast, since oxygenated hemoglobin
molecules do not weaken the magnetic field, more radio frequency
signals are emitted from each portion of neural tissue where oxygenated hemoglobin
molecules in the blood are plentiful. Being aided by these phenomena, a technique of
functional MRI can detect neuronal activity that is occurring within each
partial neural tissue having a three-dimensional size characterized by the
extent of a few millimeters. In such a
small unit of neural tissue, a few million neurons can be contained; this
technique of functional MRI allows the activation of a few million neurons in
each small unit to be detected. The brain does not have the sensitivity to feel the
activation of each individual neuron.
The brain can, however, feel images that are generated by activation of
many neurons. Moreover, the technique of functional MRI allows the brain -- that
is generating the images -- to know which areas in the brain are working
simultaneously. An experiment in which a stuffed cat is used
demonstrates an interesting suggestion.
In the brain, active areas when recognizing the entire image of the
stuffed cat are more abundant and larger than active areas when recognizing a
partial image of the stuffed cat. In
order to create an image closer to the reality of an object, more areas in the
brain must be made active. In order to
overcome a more difficult issue, efforts to work in more various areas with
wider ranges in the brain are inevitable.
A change in the blood flow in a localized area of activation of neural
tissue causes a local density of deoxygenated hemoglobin molecules to
transiently differ from a local density of oxygenated hemoglobin molecules. This fact allows us to know ourselves, i.e., to
know how many regions in the brain are working cooperatively; to know this
cerebral activity that is performed to achieve a greater societal and
ecological harmonization, which aids the continuation of our civilization. Editor’s Note: This concludes Part I of this
three-part paper. Part II will follow in the upcoming July-August
issue of this Journal. - JP Acknowledgments The author wishes to think Dr. J. L. Bernhart for
having valuable discussions about roles of science and giving valuable
suggestions on the manuscript, and Dr. A. Kharrazi for having valuable
discussions about climate change and sustainability. References [1] Nir J. Shaviv, Physical Review Letters, 89,
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