香山リカのココロの万華鏡: 脳科学と人の心 ／東京

January 10, 2016 (Mainichi Japan)
Kaleidoscope of the Heart: Brain science and the human spirit
香山リカのココロの万華鏡: 脳科学と人の心　／東京

I wonder what kind of year this is going to be.
　今年はどんな年になるのだろう。

As a psychiatrist, this year is likely to be one wherein I will take a fresh look at the question of just what exactly is the human spirit.
精神科医の私にとっては、あらためて「人の心って何だろう」と考える年になりそうだ。

The advances recently made in the field of brain science have been astounding.
近年の脳科学の進歩はすさまじい。

Ohio State University announced last year that it had finally utilized pluripotent stem cells derived from human skin cells in order to culture an eraser-sized "miniature brain," which included nearly all of the genes of a 5-week-old fetus.
昨年はついに、アメリカのオハイオ州立大学で人間の皮膚細胞由来の多能性幹細胞を使って、妊娠５週の胎児の脳のほぼすべての遺伝子を持った消しゴムサイズの“ミニチュア脳”が培養されたと報じられた。

It seems clear, then, that it will become possible within a short time frame to reproduce a human brain.
おそらく近い将来、誰かの脳をもう一つ作ることも可能になるに違いない。

On second thought, however, I'll bet that before this occurs, analyses of the brain's neural networks will proceed in a manner such that people will be able to replicate their own brain on a computer.
　いや、その前に脳の神経ネットワークの解析が進み、自分の脳をそのままコンピューター上に再現することができるかもしれない。

I remember a scene from a science fiction movie where a woman was able to converse with a computer that utilized the same pattern as the brain of her dead husband. Soon, this will actually become a reality.
ＳＦ映画では「亡くなった夫の脳と同じパターンを持ったコンピューターと妻が対話する」といったシーンも出てくるが、それが間もなく現実になろうとしているのだ。

Let's imagine that this does indeed occur.
　「もしそうなったら」と想像してみよう。

A vendor providing a "replacement brain" service comes to your house, picks up skin and hair samples of your dead family member from off the floor, and takes them away.
「脳復元サービス」の業者があなたの家を訪れ、すでに世を去ったあなたの家族の皮膚や髪の毛の一部を床から拾い上げ、持ち帰る。

You later receive notification that the artificial brain is ready, and it is delivered to your home along with an attached apparatus that allows you to converse with it.
しばらくすると「完成しました」と連絡が来て、人工の脳とそれに接続された会話装置が届く。

You flip the switch, and the nostalgic voice of your relative says, "It's been a long time! Are you studying like you should be?
I know you don't like English!" Naturally, you are also able to hold conversations with the device -- meaning that you can laugh and fight with your family member just like you always did before.
スイッチを入れると「久しぶり。ちゃんと勉強してる？　あなたは英語が苦手だから」となつかしい家族の声が聞こえてくる。もちろん対話も可能。昔と同じように笑い合ったりケンカしたりすることもできる……。

Some people are likely to think, "This is amazing! I hope this will become a reality as soon as possible!"
　「すごい。早く実現しないかな」と思う人もいるかもしれない。

Many others, however, probably feel that no matter how much a particular response pattern is able to be duplicated, it could never take the place of their beloved kin.
しかし、多くの人は、「いや、いくら反応のパターンは同じでも、それは私の愛する家族ではない」と感じるのではないだろうか。

And even if one's own brain were able to be simulated via this type of service, few are those who would feel as if they had actually attained the ability to live forever.
また、そういうサービスで自分の脳が再現されたとしても「永遠の命が手に入った」と考える人は少ないはずだ。

If this is the case, then, what does it mean to exist as a particular human being?
　だとしたら「その人である」とはいったい何なのだろう。

Is it the act of possessing a body?
からだがあるということか。

This is clearly not so, since the relatives or lover of someone whose face or other bodily features had become greatly disfigured in an accident would be unlikely to conclude that the individual had suddenly become a different person.
それは違う。事故などで顔やからだが大きく損傷されても、家族や恋人は「もうあなたではない別人になった」とは思わないはずだ。

This being the case, then, it is clear that there is a deep connection between existing as an individual being human being and the fact that we have only one life -- even though no one yet possesses a definitive answer with respect to this matter.
そう考えると、「その人である」ということと「命が一度きりであること」は深く関係しているようだ。ただ、この問題についてのはっきりした答えはまだ誰も手にしていない。

Every single individual who sits with lowered eyes and sheds tears while sitting in my office possesses their own unique spirit, and is living their one unique life -- a fact in and of itself that explains the reason why we all get hurt and suffer.
　診察室でうつむく人、涙をこぼす人。みんな「自分だけの心」を持ち、「一度きりの人生」を生きているからこそ、傷ついて苦しむのだ。

This year, then, I would like to continue probing and agonizing together with all of you with respect to the following questions: What does it mean to be human? And just what is the human spirit?
「人って何だろう」「心って何だろう」。今年も迷い悩みながら、みなさんといっしょに考えていきたい。

(By Rika Kayama, psychiatrist)
（精神科医）