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How Far Will Brain Science Research Advance and What Will It Bring?
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| Observing
the dynamics of the spine |
Mr. Takashi Tachibana (left) and Dr. Masao Ito, Director of the BSI.
A series of interviews conducted by Mr. Tachibana on brain science began with
a discussion with Dr. Ito, currently the director of the BSI, who at the time
was director of the Frontier Research System. A thought-provoking conversation
between the two regarding the frontier of brain science continued for some time.
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Tachibana: Substantial
progress has been made in the field of biological science as a result of the visualization
of gene expression by means of fluorescent materials. Because of the successful
visualization of the performance of the brain using fluorescent materials, havenÕt
there been some unexpected findings?
Ito: Using light is one of the least invasive ways of probing in the brain.
Whereas everyone knows the role of the microscope in revealing the morphology
of the brain, it is relatively recent that another property of light has come
to be widely used. Light can be used to excite molecules to produce a characteristic
fluorescence. With modern molecular methods it has become possible to express
fluorescent molecules, normally produced by marine animals, in mammalian neurons.
This method has been so successful that a world wide search is on for making such
molecular markers for more specific processes in the neuron. Such markers can
be excited deep in the tissues with the two photon methods.
Tachibana: What do you mean by "two photon excitation"?
Ito: As you know, light is carried by energy particles called photons.
The photon energy can also be thought of as the color. Molecules are excited to
fluoresce when they capture photons of a certain energy, like ultraviolet light
photons. It turns out that if the same molecule captures two photons of one half
the ultraviolet energy simultaneously, it receives the same energy as one photon
at the ultra violet light. Since the lower energy light is less damaging, it can
be used to excite marker molecules signaling what is going on in the neurons below
the surface of the brain.
Tachibana: Do you mean in live samples?
Ito: Yes, thatÕs right. It is now possible to observe for example, how
calcium ions are moving in the neuron as it performs its function or when a neurotransmitter
is released at the synapse. Such observations were only hopes and dreams just
a few years ago.
Can
we analyze language functions?
Tachibana:
I have heard that there are several research groups being planned: the communication
function research group, the architecture research group and the hardware system
research group.
Ito: Yes, and the most difficult one is the communication function research
group.
Tachibana: What sort of directions in communications research do you hope
to explore in the communication function research group?
Ito: Since the opening of the institute, I have faced many challenges but
this one is probably the most difficult. Language, including gestures is one of
the most obvious functions of the brain but has not been studied as the other
functions such as vision, audition and olfaction.
Tachibana: I have heard that you have recently expanded the cerebellum
control model of recognition functions to render it applicable to the language
system.
Ito: Yes, as a model.
Tachibana: When I first met you, you told me that conventionally, the cerebellum
had been connected with motor functions, but things might have changed, and that
the cerebellum could be used in high-level functions including language functions.
I now see that your hypothesis is gradually expanding; this is very interesting.
Ito: Yes. The cerebellum is a critically important part of the brain in
the control of motor activity of the body and has long been thought to have only
this role. However, recent evidence has begun to show that it is also involved
in cognitive functions as well. I am particularly interested in how the cerebellum
may be involved in language as a model for its involvement in cognitive functions.
Tachibana: These tools have revealed that the cerebellum is actually in
operation when we use language.
Ito: We have convincing supporting evidence for this. However, linguistics
is difficult. As Chomsky (*4) has said, "Humans have diversified languages;
however their grammatical structure is universal". If the universal grammatical
structure results from an intrinsic function of the human brain, we cannot approach
the linguistic function through studies of the brains of other animals. Usually,
we consider that our brains are similar to those of animals, and that they have
developed through a process of evolution. Although small, a chimpanzee has a bud
in the language area; this same area has expanded in humans. Although researchers
have attempted to teach chimpanzees vocal language, all attempts have been unsuccessful.
Tachibana: The reason for this failure is that the anatomical structures
required for sound-making, such as the AdamÕs apple and the palate, are different
from those of humans. Research to demonstrate that chimpanzees, though unable
to use vocal languages, are able to use language in the form of sign language
or by pointing to symbols on a character board, is in progress. Currently, the
analysis of human sign language is being actively pursued. There are standard
hand signs and it is evident that sign languages exist. However, in actual sign
languages used for practical purposes, people use things in addition to hand signs,
such as facial expressions, line of sight, and the acceleration and direction
of hand movements. It appears that if only the hand signs are converted into a
language, the amount of information which can be conveyed is very small. However,
the amount of information practically converted is fairly large. It has been proven
that sign language is a very complex form of language. In other words, we began
to realize that sign language is an established language system that differs from
general languages. Similarly, although animals do not use languages like those
of humans, they do have established various means of communication.
Ito: Yes, but Chomsky puts forth that a universal grammar emerged abruptly
in the evolution of human language functions. I think by this he implies that
a major branching occurred in human evolution which may not have occurred among
our nearest animal kin.
Tachibana: Since there is a capacity for communication which is common
among animals using general symbol manipulation in a form similar to that of a
universal grammar for humans, I wonder if chimpanzees are able to master sign
language.
Ito: We would like to explore this particular linguistic door opened by
Chomsky at the level of the formation of a universal grammar.
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Treatment
by means of neural cell transplantation
Tachibana: In the
area of protecting the brain, the day on which we conquer AlzheimerÕs disease
is drawing nearer.
Ito: Very soon, we will have effective medications.
A major sign of this disease is the accumulation of the protein b amyloid. The
rate of accumulation is very slow so that it takes 10 years before enough is present
to be seen with the microscope and a further 10 years before the symptoms of dementia
appear. Thus, it requires a total of approximately 20 years for AlzheimerÕs disease
to become apparent. Therefore, if we can identify the accumulation of b amyloid
earlier and administer medication, this disease can be prevented. The number of
AlzheimerÕs patients is increasing. Currently, the number of sufferers worldwide
exceeds 15 million. It occurs commonly and one is considered lucky if he/she is
not diagnosed with the disease beyond the age of 100. The number of sufferers
is increasing as our society ages. A cure must be found.
Tachibana: Neural cell transplantation, which involves taking some of our
own neural cells from the brain, culturing them, and then returning them to the
brain, will be effective to a certain extent. Setting aside whether or not such
a procedure is possible in the case of AlzheimerÕs disease sufferers, the transplantation
of neural cells will be applicable in the case of several other brain disorders.
Ito: Yes, by transplanting neural cells in a manner similar to rice planting.
The theory underlying neural cell transplantation has been under consideration
for a long time.
Tachibana: The technology for the in vitro culturing of
neural cells has been improving rapidly. I visited Dr. Eisuke OkanoÕs laboratory
at Osaka University, and they have developed a technology for culturing neural
cells and sorting the cultured cells using a laser beam. When I saw this technology,
I envisioned a new world which is completely different than that which we know
today.
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| Inclusion
of brain science in the elementary-school curriculum |
magnified scene by clicking
image
Spine photograph
taken by a two-photon laser microscope Fluorescent photographs of a dendrite of
a rat neuronal cell and the spine on the surface. Taken using a two-photon laser
microscope. (Provided by Dr. Atsushi Miyawaki, Head of the Laboratory for Cell
Function Dynamics) |
Ito:Following development
of the fields of understanding the brain, protecting the brain and creating the
brain, a new field has emerged recently, that of nurturing the brain. That is,
looking after the development of the brain, or assisting in the normal growth
of the brain.
Tachibana: Mechanisms to nurture the brain, or the social mechanism for
this, are part of the education system. Since these mechanisms are not functioning
well today, I believe that a lot of strange social phenomena occur. What we should
do in our education system is change the framework of the science subjects, starting
at the elementary-school level. We should include the study of brain science and
should teach it as a subject. We should teach the pupils subjects in accordance
with those studied here, including those related to understanding, protecting
and creating the brain. If this is done properly, the number of outstanding brain
scientists will increase. Furthermore, a faculty of brain science should be established
in each university. There, people can study various topics, ranging from how the
brain is used to how to use the brain, in addition to the creation of the brain
and the publication of new findings. When this is realized, the universities thus
created will be much more general universities, because brain science covers such
a broad range of topics.
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| The
most important issue: understanding the mind
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Ito:
There are many expectations in the area of creating the brain, yet there are too
many unknown parameters. For example, the mechanisms of how we recognize patterns
and motion and how to control motion have been analyzed to a certain level. However,
when it comes to issues closely related to the mind, we do not know how they work.
In the case of emotions such as happiness and sadness, it is likely that threshold
values are set for neurotransmitters such as dopamine and adrenaline; when the
signal level is higher than the threshold value people are happy, and when the
level is lower than the threshold value, people are sad. We can speculate on this
topic, but it is very difficult to reproduce situations using a computer or a
robot.
Tachibana: The definition of emotion is an important issue.
Ito:
Yes, you are right. But we are able to reproduce something like emotion.
Tachibana: Actually, it is very difficult to completely understand our
mind and emotions isnÕt it?
Ito: If we rely upon subjective experiences,
we cannot understand these at all. Nonetheless, we have recently come to understand
the brain fairly well; therefore, an increasing number of people believe that
we shall be able to understand our mind and emotions fully in the near future.
The understanding of our mind and emotions is the most significant issue of the
21st century. I feel that we will be able to make substantial progress.
Tachibana: You wrote somewhere that understanding the brain means understanding
everything about human beings, in addition to understanding the many different
aspects of humanity including our societies and histories. Furthermore, when we
think of the history of the evolution of the brain, all histories of living things
are represented by human brains.
Ito: The apex of evolution is the human
brain.
Notes:
*1 Frontier Research System
It was established at the Institute of Physical and Chemical Research (RIKEN)
in 1986 and is an organization which carries out advanced basic research (frontier
research) in unexplored areas globally, intensively and flexibly.
*2 Postdoctoral fellow (postdoc)
Researchers who have received a doctoral degree and are working in a temporary
position before assuming a permanent research (educational) position. A trainee
with a doctoral degree.
*3 Advanced Technology Development Center
It was established with the aim of advancing research related to the creation
of new technologies which can be the basis for brain science research. The responsibilities
are divided into research for the development of a new measurement technology
and the development of new biological technologies. It includes research resources
such as facilities for experimental animals and jointly used devices and equipment.
*4 Chomsky
Noam Avram Chomsky is a Professor of Massachusetts Institute of Technology. Born
in the U.S.A. in 1928, he is a theoretical linguist.
Pictures of interviewer by Nariaki Ohnishi |
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