社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

総説

The ethical and philosophical issues concerning the clinicalapplication of brain–machine interface technology:
from the perspective of rehabilitation medicine
ブレインマシンインターフェイス技術の臨床応用における倫理的、哲学的問題について―リハビリテーション医療の視点から―
Toshiya YUKI
結城俊也
Chiba Central Medical Center
千葉中央メディカルセンター

抄録
本論文の目的は、リハビリテーション医療におけるブレインマシンインターフェイス技術の適用に関する倫理的、哲学的問題について考察することである。今回は特に以下の３点について議論する。1. ブレインマシンインター
フェイス技術の医療への応用に対する条件について、2. ニューロ・エンハンスメント（神経増強技術）における倫理的、哲学的問題について、3. ブレインマシンインターフェイス技術が個人のアイデンティティを変容させてしまうことへの危惧について。
ブレインマシンインターフェイス技術により生じる身体の変容は、自分自身の身体に対する私たち認識を覆す可能性を秘めている。もし私たちの社会が BMI 技術を受け入れるのであれば、既存の人間観、すなわち自由で自律的な近代的自我としての人間観の変容も受け入れるという心の準備が必要であろう。医療の歴史が人類の文化の歴史と同じくらい長いという事実を考えれば、本論で提起された諸問題は、歴史的、文化的、そして社会的文脈のなかで、それぞれの国による継続的な検討が必要であると考える。
Abstract
Purpose : This study examines the ethical and philosophical issues concerning the introduction of BMI
technology in rehabilitation medicine. In particular, the following three points are discussed. 1. Conditions forapplication of BMI technology to medical treatment. 2. Ethical and philosophical issues of“Neuro-enhancement”. 3.
A fear of BMI technology changing one’s identity. Conclusion: Bodily transformation because of BMI technology
will disrupt our understanding of the body as one’s own. If our society accepts BMI technology, we need to beprepared to accept the changing view of what a human being is (i.e., the change of the modern self as a free
and autonomous agent). Considering the fact that the history of medical care is as long as the history of humanculture, this paper raised various issues that require further examination in the historical, cultural, and social
contexts in each country.

― 5 ―社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

キーワード：ブレインマシンインターフェイス技術、倫理的、哲学的問題、リハビリテーション医療、ニューロ・
エンハンスメント
Key words：BMI technology, the ethical and philosophical issues, rehabilitation medicine, Neuro-enhancement.

Introduction

1. Conditions for application of BMI technology to
medical treatment.

The brain–machine interface (BMI) or brain–

2. Ethical and philosophical issues of “Neuro-

computer interface (BCI) that utilizes bothenhancement”.

neuroscience and information communications

3. A fear of BMI technology changing one’s

technology is now being used in the medical field.
Hammad et al1）

identity.

previously showed that a BCI“aimsto restore functional movements in subjects with

The goal of this paper is not to provide answers

neuromuscular disorders by interpreting neural

but to raise our intelligence by examining complex

signals recorded from the brain and translating theissues.

inferred information into control signals for external
1. Conditions for application of BMI technology todevices such as a prosthetic limb or to guideelectrical stimulation of the patient’s own limbs.”
2）

medical treatment

mentions that“BCI technology might

It is necessary to weigh the benefits and risks ofalso restore more effective motor control to people

introducing a new technology in clinical situations.

after stroke or other traumatic brain disorders by

Clinical trials that measure effects are necessary tohelping to guide activity-dependent brain plasticity

demonstrate the benefits of short-term and future

by use of EEG brain signals to indicate to the patientuses of BMI technology. However, it is difficult tothe current state of brain activity.”This technology

judge objectively the benefits and risks of BMI

Daly et al

may prove to be a useful rehabilitation tool fortechnology because this technology aims to treat

patients with severe disabilities, and the number ofthe brain, which is directly linked to the humanstudies on this has increased.3-7）At the same time,mind. Furthermore, in clinical trials of applying

some ethical and philosophical issues concerning a

BMI technology in rehabilitation medicine, the level

direct connection between the brain and machinesof patients' cooperation may affect the treatment

For example, there is the risk ofoutcome. In fact, many studies have shown thatinvasion to the brain, whether to permit the use of

improvement of motor function is influenced by

medical technology for enhancing a condition beyond

the degree of concentration on the therapy by thethe normal condition, the invasion of privacy due topatient or the level of motor imagery.10-12）However,mind-reading and the potential for the collapse of theMulder13）reported that the effects of motor imagery

8-9）

have been raised.

general concept of an individual that is autonomous

differ according to not only individual ability toand self-determined. These issues highlight thementally simulate the action, but also the cooperation

importance of examining the influence of BMI

and concentration of the learner. More generally,

technology on human society. More specifically, it isbiomedical research related to physiologicalvitally important to consider beforehand the potential

reactions caused by the intake of drugs excludes theof BMI technology to impose an undesired influence

subjectivity of the patient from the experiment. The

on humans. Based on the above, this study examines

determination that a new medicine is more effective

the ethical and philosophical issues concerning thethan a conventional medicine is validated according

introduction of BMI technology in rehabilitation

to the hypothetical model, and high reliability is

medicine. In particular, the following three points are

determined by double-blind randomized controlled

discussed.

trials. On the other hand, when measuring the― 6 ―社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

effect of applying BMI technology for the treatment

BMI technology should be considered from theof stroke, it is necessary to clarify the process ofperspective of not only scientific validity but also

neuronal network reconstruction caused by conscious

from an ethical or moral standpoint.

body movement. Moreover, it may be necessary
2. Ethical and philosophical issues of “Neuro-

to verify whether the therapy can cause favorable

enhancement”

changes in the connections of neurons and synapses,in the quantity of the neurotransmitters, and in‘Beyond Therapy : Biotechnology and thethe properties of receptors. Accordingly, so long asPursuit of Happiness’by The President's Council

the treatment outcome is influenced by the level ofon Bioethics was published in 2003. 17）This reportpatients' cooperation, it is difficult to determine thedefines therapy as bringing a condition back toscientific validity for BMI technology in rehabilitation

normal, and “beyond therapy” as enhancing a

medicine.

＊1

condition beyond normal. However, the realm of
biotechnological beyond therapy is a hard-to-define

Some reports show that electrical potentials such
14）

15）

that are detectedgray zone where ethical judgments are difficult.

from the scalp or cortical surface can be used in

Chaotic discussions have focused on having better

rehabilitation medicine. It is well known that thechildren, superior performance, ageless bodies, andmu rhythm is suppressed when one performs or

happier souls. The report says that the vast majority

16）

of council members feel that beyond therapy should

pointed out that“therapists could use the change

be approached cautiously and that some believe thisin the mu rhythm to get immediate feedback abouttype of therapy should be regulated. Some people arewhether a subject is optimally prepared to maketrying to use genetic manipulation, nanotechnology,

a movement and has focused his motor attention.”and robotics to improve humans after birth, andEven if this feedback may enhance the presynaptic

they insist that society should not be limiting theas the mu rhythmor P300

visualizes performing a motor action. Dobkindrive to a cell population and network that patients

pursuit of happiness via the use of transhumanist

use to plan the trajectory of the foot for walking,technology. The technology itself is said to bewhich in turn may increase motor output and‘value-neutral’because the value judgment of it

16）

improve the timing and completeness of movements ,being right or wrong depends on the social context.

the effect may depend on the patient’s motor attention.

Generally, scientists tend to seek the highest

Consequently, compared with the method for

degree of technological development. Therefore, thedetermining the effect of a new medicine, it is very

technological developments that sufficiently enhancedifficult to verify the treatment outcome reflectedfunctions may spread throughout society. Manyin the patient’s mental condition.

＊1

ethical issues have to be solved if someone motivatedIn this situation,

should patients choose the invasive BMI technique

by desires for sensual pleasures makes use ofover other therapy?

biotechnology. An individual could also attemptStandard clinical treatments do not provide any

to gain superior strength or performance, like theguarantees for identical outcomes because physical or‘Hulk’. However, from a moral perspective, if theymental conditions differ between individual patients.

have a greater ability to do heavy work compared

There is no indication that invasive treatments ofto others, they will never be highly appreciated.

the brain, such as the BMI technique, would be any

Moreover, it is expected that this technology would

different. Furthermore, evidence obtained by medical

not become commonplace in society. Taking thisworkers or researchers is required to apply BMI

into consideration, if the use of biotechnology or

technology to standard treatment in rehabilitation

BMI technology is regulated, it will be necessary toHere, it should be noted that advanced

adjust the regulations based on the intended target

technology always introduces uncertainty, andof the therapy. Nevertheless, the differences between

medicine.

＊2

― 7 ―

社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

therapy and enhancement seem to have been

3. A fear of BMI technology changing one’s identity

blurred. To clarify the difference between the two,

BMI technology that assists with defects in motor

it is essential to answer questions such as ‘What isfunction is used as an example in this section to

the desirable normal condition?’ or ‘Is the deviationconsider identity crises and human nature. Thesefrom a healthy or normal condition simply because

technologies are broadly classified into two types:of a disease?’If stroke patients are given functions

invasive and noninvasive. The invasive type includes

superior to those of healthy elderly individuals of theimplanting multiple electrodes in the brain, and thesame age by BMI technology, should it be considerednoninvasive type involves detecting a weak biosignal

beyond therapy?

from the surface of the skin. The extracted signals

indicated that“the question I address

are electrically connected to the joint and limbs

is not whether attaching artificial limbs or enhancing

via a machine to provide aid for easily moving theparticular traits or capacities would dehumanize

hands or feet. These technologies are expectedor undignify persons but whether nonbiologicalto function as an effective treatment in clinicalJotterand

9）

entities introduced into or attached to the humanapplications, and when established, could lead tobody contribute to the “augmentation” of humanserious ethical issues, such as the uncertainty of

dignity.”Whether or not we can use BMI technology

body ownership; in other words, the collapse of thedepends on the augmentation of human dignity, andsense that the body is one’s own. Humans growdiscussions about human dignity and posthumanemotionally or mature through physical states orWhen examining the issue

experiences throughout their lifetime. The bodyof enhancement or neuroethics, an importantis a place where one’s emotions exist; the humanconsideration is that there is no simple solution

body can even be said to be the organ of emotion.

to this complex problem. Considering that healthMoreover, we not only have explicit knowledge, suchand disease are socially constructed concepts, theas verbalized information, but embodied knowledge,

dignity are essential.

＊3

concepts of normal and abnormal are also similarly

such as a way of moving the body based on theconstructed. Thus, the individual desire to become

internalization of physical experiences. ＊ 4 A lack ofstronger and faster reflects a sense of values and theembodied knowledge means that a smooth dailystate of society. Notably, a society’s values become

life or social life is difficult because there is a closea kind of pressure, and there is the risk that an

relationship between mind and body. Accordingly,

individual’s freedom to choose a therapy becomes

the sense of body is an important requirement for

restricted. That is to say, in a society in which it

developing rich emotions and acquiring embodied

is common to use BMI technology for treatments,

knowledge. Our anthropocentric view of the world

people may be unable to choose an alternative

may be greatly influenced by bodily changes induced

therapy. Moreover, the problem of enhancement byby cyborgization that changes our emotions or

BMI technology can include enhancing a function

personality.

that is desirable, as well as excluding an undesirable

Here, we consider the reaching motion exercise

function, such as treatment to remove a specificof amputees by a robotic arm using BMI technology

state of mind by electric stimulation of the brain. If

as an example. First, a brain signal related to the

BMI technology eventually becomes mainstream, isreaching motion must be converted to a mechanicalit an oversimplification that a single misstep could

signal by a machine, and an amputee must perceive

give rise to eugenics? Thus, in the case where BMI

the motor information feedback from the robotic arm.

technology is applied, it is necessary to obtain aThis feedback information must be converted to vitalsocial agreement about‘What is normal?’ or ‘What issigns. It is necessary to understand how this kind ofan acceptable range of therapeutic applications?’

interaction between the human body and a roboticarm is comprehended, as it is completely different― 8 ―社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

Conclusionfrom a normal biological phenomenon. Thus, when
the amputees lift something with the robotic arm,

Ethical and philosophical issues from threethey will probably feel a new mental representation.

perspectives were discussed in light of the future

Amputees are then forced to change their bodyprevalence of BMI technology in rehabilitation

image. A constructed social relationship throughmedicine. When discussing these issues, both theembodied interaction by humans is also expected tobenefits and risks of BMI technology should bechange similarly. When amputees become able toconsidered. Because the discourse itself about thecontrol the robotic arm the same way as their own

risks of BMI technology acts as a social pressure,body due to advances in technology, there could bethere is a possibility of undermining the benefits tophilosophical issues such as ‘Who am I?’ or ‘What

patients who need this technology. Paraphrasing

is my body?’ Even Descartes, well known for his

Baron 19）, technological achievement is not a great

concept of methodological doubt, i.e., a method of

invention in itself; its importance depends on what it

doubting everything that exists for the pursuit of truth,

means for humans and how it will alleviate sickness-never doubted that the body is one’s own. However,related pain. Therefore, we have to consider thebodily transformation because of BMI technology

social and cultural perspective of happiness for all

will disrupt our understanding of the body as one’s

humankind in technological development. ＊ 6 In aown. These points indicate blurring of the boundary

report on introducing a caregiver robot into nursing

between nonbiological artifacts and humans.

care institutions, nearly 40% of respondents replied

The Japan Science and Technology Agency hasthat ‘facility users and their families are eager

succeeded in moving a humanoid robot via data thatfor manual care and they will not accept care by

is detected from cortical brain activity in a monkey

machine.’ 20）Although it will be appreciated, newand transmitted through an internet interface

technology will not immediately be fully accepted18）

between the U.S.A. and Japan in real time . Thisby the social community. Current problems include

monkey essentially has another body at the remote

how to introduce BMI technology into daily life

location. In other words, the individual is separated,

and whether it will be naturally accepted by many

thus, jeopardizing the sense of identity. An identity

people. Considering the fact that the history ofcrisis arises in organ transplant patients, who, as

medical care is as long as the history of humanrecipients, are given an organ from a donor; BMI

culture, this paper raised various issues that require＊5

technology may also lead to the same problem.
success of this experiment

18）

further examination in historical, cultural, and social

The

contexts in each country. ＊7means the conventional

concept of human embodiment, that one brain
controls one body, begins to weaken. Thus, ourNotes

understanding of the individuality of human beings＊1 : As pointed out earlier, the main aim of

is not absolute. The externalization of brain function

rehabilitation medicine is to restore physicalbased on a direct connection between the brain and aabilities lost to injury or disease in order to function

machine raises abstruse philosophical issues, such as

in a normal or near-normal way. Therefore, it‘What defines a human being?’or‘What defines theis difficult to evaluate quantitatively the efficacy

human brain activity of the identical personality?’of rehabilitation treatment. Moreover, cognitive

If our society accepts BMI technology, we need toability or motor attention influences the therapeutic

be prepared to accept the changing view of what aeffect. However, the advent of positron emission

human being is (i.e., the change of the modern self as

tomography, functional magnetic resonance imaging,a free and autonomous agent).

and transcranial magnetic stimulation as noninvasive
evaluation methods through the development of
medical electronics enabled observation of cerebral― 9 ―社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

nerve activity that was once difficult to detect. I hope

＊5 : Recipients of organs transplanted from donors

that progressive use of these devices contributes tohave suffered from identity crises, such as notassessment of the treatment effect of rehabilitation

being able to“feel”their own organ and having

medicine in the future.

their identity jeopardized. Through experiences of＊2 : Clinical practice guidelines for the use ofheart transplantation, French philosopher Jean-Luc

BMI technology will likely be prepared throughNancy22）came to feel,“In me there is the intrus, andthe accumulation of case reports. To accomplish

I become foreign to myself”, and he philosophized

this, healthcare practitioners need to report what

about what the subject is. BMI technology is none

was diagnosed, the clinical manifestation, anyother than the intervention by‘what others callmedical treatment, the treatment period andscientific technology’to the brain as an important

clinical outcomes. A report on a person's mentalorgan of human intelligence or memory. Therefore,and psychological status is especially important.

the possibility that BMI technology will lead to an

When a change in human nature is suspected ofidentity crisis cannot be ruled out. Considering theresulting from treatment utilizing BMI technology,

sense of‘I’being nothing but‘I’supported by myit is necessary to re-examine the validity of thismemory, rewriting this memory by BMI technology

treatment method.

could cause serious issues, such as“Who is the＊3 : It is difficult to establish a common definition

subject?”We must be prepared to deal with theof “human dignity” because of the differences

issues surrounding technological intervention in thein thoughts and religions between periods andbrain.

regions. However, any consideration of human＊6 : Does BMI technology contribute to humandignity must consider the following points. Fromhappiness or well-being? Deep brain stimulationa moral perspective regarding human dignity,

is currently being explored as a treatment for

the externalization of brain function based on a

psychiatric disorders, such as major depression. If

direct connection between the brain and a machine

this treatment using electrical impulses can makeshould not be done. However, what are the moral

patients happier, we wonder if this truly contributes

obligations if a patient’s pain can be relieved by BMI

to well-being. In a thought experiment known astechnology? Thus, we cannot simply say that use of

the Experience Machine (a machine for realizing

BMI technology is still immoral. The alleviation of aexperience as desired), Robert Nozick23）says well-patient’s pain by BMI technology would be vital inbeing is not only constituted by mental states but

maintaining human dignity. This is a difficult problem

also by living in contact with reality. Accordingthat cannot be solved immediately. For details, see

to Nozick, people would not want to obtain happy

Jotterand’s report.

feelings using the Experience Machine, they would

9）＊4 : The body is a very important medium throughwant to make decisions about their life in the real

which to recognize the external world. According

world. From this perspective, if self-identity changes

to M. Merleau-Ponty's phenomenological thought on

depending on the BMI technology, complex issues

body21）, the human body functions as a medium insuch as‘What part of me is making the decisions?’

which one takes recognition of the actual world byor‘Does achieving well-being mean changing mythe reciprocity between body and the environment.

identity?’may arise. For more information, see

For example, it's not that children know the concept

Schermer’s report. 8）‘chair’by learning the linguistic definition of a

＊7 : We must consider peaceful uses of BMI‘chair’, it's just that they already knew about ittechnology. Particularly, BMI technology shall not

through the physical act of‘sitting in the chair'.

be used for war or crime, nor shall it be used for

Therefore, the transformed body will almost

mindreading or mind control. Countermeasurescertainly recognize the external world differently.

to prevent misuse of BMI technology will be― 10 ―

社会医学研究．第 32 巻 1 号．Bulletin of Social Medicine, Vol.32（1）2015

needed. Three fundamental rules concerning

Brötz D, Fallgatter A, Birbaumer N, Sitaram R,

the development and use of nuclear power will

Caria A : Lower Limb Movement Preparation

probably be a good reference for establishing thesein Chronic Stroke : A Pilot Study Toward an

countermeasures. However, because brain function

fNIRS-BCI for Gait Rehabilitation. Neurorehabil

has not been studied sufficiently, formulation of a

Neural Repair. 2014 Jan 30. [Epub ahead of print]

code of ethics and code of conduct will be difficult.

PMID : 24482298 [PubMed - as supplied by

Nuclear weapons may bring about the annihilation

publisher]of man. On the other hand, BMI technology may8）Schermer M : Health, happiness and humandehumanize people. We expect discussion to proceedenhancement-dealing with unexpected effects ofwith due consideration toward differences between

deep brain stimulation. Neuroethics. 2013, 6 : 435-

nuclear power and BMI technology.

445.
9）Jotterand F: Human dignity and transhumanism:

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