最近NYTで〈脳還元主義〉を批判するテクストを幾つか読んだ；
Andy Clark “Out of Our Brains” http://opinionator.blogs.nytimes.com/2010/12/12/out-of-our-brains/ *1
ANDY CLARK “Extended Mind Redux: A Response” http://opinionator.blogs.nytimes.com/2010/12/14/extended-mind-redux-a-response/ *2
TYLER BURGE “A Real Science of Mind” http://opinionator.blogs.nytimes.com/2010/12/19/a-real-science-of-mind/ *3
さて、大晦日にはオリヴァー・サックス先生*4が脳は凄いんだぞ！ というエッセイを寄稿している；
“This Year, Change Your Mind” http://www.nytimes.com/2011/01/01/opinion/01sacks.html
人間の脳の中でも、感覚機能や運動機能とともに言語や思考のような高次の認知機能も担う大脳皮質は、私たちが歳を取ってからでもかなりの程度で「最配線（rewire）」が可能であり、視力や聴力の喪失といったダメージからの驚くべき恢復力を有している。
或る聾者の例；
彼女は他人の唇の動きを読み、視覚によって他人の声を「聴く」。
For example, one patient of mine who had been deafened by scarlet fever at the age of 9, was so adept at lip-reading that it was easy to forget she was deaf. Once, without thinking, I turned away from her as I was speaking. “I can no longer hear you,” she said sharply.“You mean you can no longer see me,” I said.
“You may call it seeing,” she answered, “but I experience it as hearing.”
Lip-reading, seeing mouth movements, was immediately transformed for this patient into “hearing” the sounds of speech in her mind. Her brain was converting one mode of sensation into another.
また、カリフォルニア大学デイヴィス校の生物学者Geerat Vermeijは３歳のときに失明したが、貝殻の輪郭の微細なヴァリエーションを指でなぞることによって、多くの貝の新種を発見している。著述家のVed Mehta*5も子どもの頃に失明したが、彼は（字義的な意味で）空気を読む――”using “facial vision” — the ability to sense objects by the way they reflect sounds, or subtly shift the air currents that reach his face.” ３歳で失明し、2009年に亡くなったBen Underwoodという少年*6は唇をクリックして、それに対する対象物からのエコーを読むという「海豚みたいな戦略」を使い、自転車に乗ったりTVゲームをしたりしていた。
また、
People like Ben Underwood and Ved Mehta, who had some early visual experience but then lost their sight, seem to instantly convert the information they receive from touch or sound into a visual image — “seeing” the dots, for instance, as they read Braille with a finger. Researchers using functional brain imagery have confirmed that in such situations the blind person activates not only the parts of the cortex devoted to touch, but parts of the visual cortex as well.
さらに、これが本題なのだろうけど、脳のこうした可塑性というのは障碍者だけに見られるのではないという；
One does not have to be blind or deaf to tap into the brain’s mysterious and extraordinary power to learn, adapt and grow. I have seen hundreds of patients with various deficits — strokes, Parkinson’s and even dementia — learn to do things in new ways, whether consciously or unconsciously, to work around those deficits.
そして、脳を鍛え・活性化するためには音楽がいいよという話になり、とにかく新しい経験をし・新しい仕方で考えることによって、脳は成長していくという結論になる；
Neuroplasticity — the brain’s capacity to create new pathways — is a crucial part of recovery for anyone who loses a sense or a cognitive or motor ability. But it can also be part of everyday life for all of us. While it is often true that learning is easier in childhood, neuroscientists now know that the brain does not stop growing, even in our later years. Every time we practice an old skill or learn a new one, existing neural connections are strengthened and, over time, neurons create more connections to other neurons. Even new nerve cells can be generated.
これは（例えば）教育や福祉にも重要なインプリケーションを持っていると思う。政治的にも。
Music is an especially powerful shaping force, for listening to and especially playing it engages many different areas of the brain, all of which must work in tandem: from reading musical notation and coordinating fine muscle movements in the hands, to evaluating and expressing rhythm and pitch, to associating music with memories and emotion.Whether it is by learning a new language, traveling to a new place, developing a passion for beekeeping or simply thinking about an old problem in a new way, all of us can find ways to stimulate our brains to grow, in the coming year and those to follow. Just as physical activity is essential to maintaining a healthy body, challenging one’s brain, keeping it active, engaged, flexible and playful, is not only fun. It is essential to cognitive fitness.
ところで、このテクストを読んで、中村雄二郎『共通感覚論』を再度捲ってみたいなと思ったのだが、生憎手許になし。
- 作者: 中村雄二郎
- 出版社/メーカー: 岩波書店
- 発売日: 1979/05/28
- メディア: 単行本
- クリック: 3回
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