Brain: Malleable, Capable, Vulnerable
ABIGAIL ZUGER, M.D.
Times, May 29, Books.
In bookstores, the
science aisle generally lies well away from the self-help section, with
hard reality on one set of shelves and wishful thinking on the other.
But Norman Doidge’s fascinating synopsis of the current revolution in
neuroscience straddles this gap: the age-old distinction between the
brain and the mind is crumbling fast as the power of positive thinking
finally gains scientific credibility.
The credo of this
revolution is neuroplasticity — the discovery that the human brain is as
malleable as a lump of wet clay not only in infancy, as scientists have
long known, but well into hoary old age.
neuroscience, the adult brain was considered an immutable machine, as
wonderfully precise as a clock in a locked case. Every part had a
specific purpose, none could be replaced or repaired, and the machine
was destined to tick in unchanging rhythm until its gears corroded with
experimental techniques suggest the brain is more like a Disney-esque
animated sea creature. Constantly oozing in various directions, it is
apparently able to respond to injury with striking functional
reorganization, and can at times actually think itself into a new
anatomic configuration, in a kind of word-made-flesh outcome far more
characteristic of Lourdes than the National Institutes of Health.
So it is forgivable that
Dr. Doidge, a Canadian psychiatrist and award-winning science writer,
recounts the accomplishments of the “neuroplasticians,” as he calls the
neuroscientists involved in these new studies, with breathless
reverence. Their work is indeed mind-bending, miracle-making,
reality-busting stuff, with implications, as Dr. Doidge notes, not only
for individual patients with neurologic disease but for all human
beings, not to mention human culture, human learning and human history.
And all this from the
fact that the electronic circuits in a small lump of grayish tissue are
perfectly accessible, it turns out, to any passing handyman with the
For patients with brain
injury, the revolution brings only good news, as Dr. Doidge describes in
numerous examples. A woman with damage to the inner ear’s vestibular
system, where the sense of balance resides, feels as if she is in
constant free fall, tumbling through space like an ocean bather pulled
under by the surf. Sitting in a neuroscience lab, she puts a set of
electrodes on the surface of her tongue, a wired-up hard hat on her
head, and the feel of falling stops. The apparatus connects to a
computer to create an external vestibular system, replacing her damaged
one by sending the proper signals to her brain via her tongue.
But that’s not all. After
a year of sessions with the device, she no longer needs it: her brain
has rewired itself to bypass the damaged vestibular system with a new
A surgeon in his 50s
suffers an incapacitating stroke. He is one of the first patients to
enroll in a rehabilitation clinic guided by principles of
neuroplasticity: his good arm and hand are immobilized, and he is set
cleaning tables. At first the task is impossible, then slowly the bad
arm remembers its skills. He learns to write again, he plays tennis
again: the functions of the brain areas killed in the stroke have
transferred themselves to healthy regions.
An amputee has a bizarre
itch in his missing hand: unscratchable, it torments him. A
neuroscientist finds that the brain cells that once received input from
the hand are now devoted to the man’s face; a good scratch on the cheek
relieves the itch. Another amputee has 10 years of excruciating
“phantom” pain in his missing elbow. When he puts his good arm into a
box lined with mirrors he seems to recognize his missing arm, and he can
finally stretch the cramped elbow out. Within a month his brain
reorganizes its damaged circuits, and the illusion of the arm and its
Research into the
malleability of the normal brain has been no less amazing. Subjects who
learn to play a sequence of notes on the piano develop characteristic
changes in the brain’s electric activity; when other subjects sit in
front of a piano and just think about playing the same notes, the same
changes occur. It is the virtual made real, a solid quantification of
the power of thought.
From this still
relatively primitive experimental data, theories can be constructed for
the entirety of human experience: creativity and love, addiction and
obsession, anger and grief — all, presumably, are the products of
distinct electrical associations that may be manipulated by the brain
itself, and by the brains of others, for better or worse.
For neuroplasticity may
prove a curse as well. The brain can think itself into ruts, with
electrical habits as difficult to eradicate as if it were, in fact, the
immutable machine of yore. Sometimes “roadblocks” can be created to help
steer its activity back in the desired direction (like bandaging the
stroke patient’s good arm). Sometimes rewiring the circuits requires
hard cerebral work instead; Dr. Doidge cites the successful Freudian
analysis of one of his patients.
And, of course, the
implications for external re-engineering of the human brain are ominous,
for if the brain is malleable it is also endlessly vulnerable, not only
to its own mistakes but also to the ambitions and excesses of others,
whether they are misguided parents, well-meaning cultural trendsetters
or despotic national leaders.
The new science of the
brain may still be in its infancy, but already, as Dr. Doidge makes
quite clear, the scientific minds are leaping ahead.
<< về trang Tài liệu chữa bệnh >>