Karen,
Thank you for posting an interesting review of "The Mind and the Brain".
It's encouraging stuff. It's good to know that I, even at my age of 67, am
being aided by the creation of new neurons in my struggle to understand the
book I'm currently reading ("What Evolution Is", published 2002) by the
doyen of all living biologists, Ernst Mayr, who, at 97, has undoubtedly
managed to grow many new neurons in the writing of it.
Yes, neuroscientists have been too restricted in their view of what the
brain may or may not be able to do, even in advanced old age. However,
let's not get carried away by the current swing. It's still a fact that as
we grow older memory fades, our powers of recall falter, our short-term
memory (the hippocampus) certainly fails us on many occasions every day and
there's little we can do about it. We certainly can't grow enough new brain
cells to remedy the deficit.
A friend of mine in his 80s, still a good bass singer in Bath Choral
Society and fearfully intelligent (as one might imagine an ex-Patents
Director of General Electric to be) appeared on a TV quiz show recently. He
actually did quite well, reaching quarter finals or something like that,
before losing to a person half a century younger. He told me later that
there were several questions he knew he could have answered when younger
but couldn't now.
So we must not go overboard about it. I may very well be able to learn
Chinese, say, at my present age, but I'll never be any good at it because
the specialist types of brain cells needed to store and pronounce Chinese
phonemes disappeared within months of my being born because they were never
exercised in an English household. (I am, however, setting up a competition
among my grandchildren to learn Chinese. The difficulty is not with them,
of course, but with their parents who are already too old to realise just
how important the Chinese language is going to be in anybody's career in 20
years' time.)
I like to think that I am still creative. In the sense that I'm still able
to reshuffle existing ideas in my head and reformulate them I suppose I am
but, as for creating a really innovative idea that's going to change the
world, that's most unlikely. That will have to be left to younger people
whose brains are not yet full up with tired old ideas and are still capable
of making new networks.
Keith Hudson
<<<<<<
Survival of the Busiest
Parts of the Brain That Get Most Use Literally Expand And Rewire on Demand
"The Mind and the Brain: Neuroplasticity and the Power of Mental Force." by
Jeffrey M. Schwartz, M.D., and Sharon Begley. (2002 ReganBooks). ISBN:
0060393556.
For the conventional wisdom on our gray matter, just open any lavishly
illustrated brain book. There, detailed diagrams map out specialized brain
structures: areas that generate speech and areas that process -- vision,
areas that sense sound and areas that detect when you touch your left big toe.
The diagrams resemble nothing so much as zoning maps produced by the most
rigid land use board. Every bit of neural real estate is assigned a job,
reflecting the decades-long belief that different parts of the brain are
hardwired for certain functions.
This view of the brain dates back to 1857, when French neurosurgeon Paul
Broca discovered that particular regions are specialized for particular
functions, such as language. His and subsequent discoveries gave rise to
the dogma of the hard-wired adult brain, and it had profound real-world
consequences. It held that if the brain sustained injury through stroke or
trauma to, say, a region responsible for moving the left arm, then other
regions could not step up to the plate and pinch-hit. The function of the
injured region would be lost forever. And it implied that if, by the age
of 12 or so, you had not recruited neurons to the specialized task of
playing the violin, for instance, or learning a second language, then you
might as well give up: your old brain was simply not going to learn new
tricks.
But that dogma has been under assault in recent years. Although specific
portions of the brain do, usually, specialize in certain tasks, the brain
is much more adaptable and renewable than previously thought-and that's
true throughout life.
Animal experiments provided the first hints that the brain is able to
change dramatically after childhood. When lab monkeys practiced - and
practiced - the trick of using a single finger to reach into a tiny dish
and grab a morsel of food, the brain region devoted to fine motor control
of that finger grew like suburban sprawl. And these were grown-up monkeys.
Even the adult brain is 'plastic', able to forge new connections among its
neurons and thus rewire itself. Sensory input can change the brain, and
the brain remodels itself in response to behavioral demands. Regions that
get the most use literally expand. In terms of which neural circuits
endure and enlarge, you can call it survival of the busiest.
In 1993, Alvaro Pascual-Leone, then at the National Institute of
Neurological Disorders and Stroke, led the search for what would become one
of the earliest findings in human neuroplasticity. Does anyone, he
wondered, habitually experience powerful tactile stimulation to a
particular portion of their body? Of course: blind people who read Braille
with their fingertips.
Dr. Pascual-Leone recruited 15 proficient Braille readers and wired them up
so he could measure their somatosensory cortex-the part of the brain that
registers and processes the sense of touch. Then he administered weak
electrical shocks to the tip of their right forefingers (the 'reading
finger'), recording which parts of the somatosensory cortex registered the
sensation. He did the same thing to the blind people's left index finger,
and to fingers in non-Braillereaders that don't get exceptional use.
The result was unmistakable. In the Braille readers, the area of
somatosensory cortex devoted to the reading finger was much larger than the
comparable area for fingers in both blind and sighted people who don't have
such demands put on them. It was a clear case of sensory input changing the
brain. The cortical region processing that input had expanded, with a
consequent increase in sensitivity. That would explain how Braille readers
are able to make such fine discriminations among patterns of tiny raised dots.
By the spring of 1995, Edward Taub was also exploiting the ability of the
brain to rewire itself. The University of Alabama, Birmingham, scientist
was developing a revolutionary new therapy for stroke patients. The goal
was to enable an intact area of the brain to take over for a region knocked
out by stroke. But Dr. Taub was sure that neuroplasticity went beyond
damaged brains. His goal was to see how normal behaviors changed brain maps.
One evening that spring, he and his wife Mildred Allen, a lyric soprano who
had been a principal artist at New York's Metropolitan Opera in New York,
were having dinner in Germany with a group of neuroscientists. Casting
around for a study they could collaborate on, Dr. Taub asked the group: Is
there any normal activity that uses one hand way more than the other? The
scientists were flummoxed, but Ms. Allen chimed in, "Oh, that's
easy-playing a string instrument."
When a right-handed musician plays the violin, four digits of the left hand
continuously finger the strings. (The left thumb grasps the neck of the
violin, undergoing only small shifts of position and pressure.) The right,
or bowing, hand undertakes far fewer individual finger movements. Might
this pattern leave a trace on the cerebral cortex?
To find out, the scientists recruited six violinists, two cellists and one
guitarist, all of whom had played their instrument for seven to 17 years,
as well as six nonmusicians. The volunteers sat still while a pneumatic
stimulator applied light pressure to their fingers to record neuronal
activity in the part of the brain that processes the sense of touch.
There was no difference between the string players and the nonmusicians in
how much of the cortex was devoted to 'feeling' the fingers of the right
hand. But there was a huge difference when it came to the left hand: The
amount of brain territory devoted to those fingers had increased
substantially. That increase was greatest in musicians who began to play
before the age of 12.
But to Dr. Taub, the most dramatic finding was that even in people who took
up the violin as adults, regular practice had changed their brains. Their
cortex had rezoned itself so that more neurons were assigned to the fingers
of the left hand. "Even if you take up the violin at 40, you still get
brain reorganization," he says.
These were the opening shots in what would become a revolution in treatment
for stroke, depression, obsessive-compulsive disorder, Tourette's syndrome
and other brain diseases. All were based on the discovery that the brain
has the ability to change in response to the input it receives.
At the University of California, San Francisco, researchers led by Michael
Merzenich had shown that sound has the power to reshape the brain in lab
monkeys. Across the country, at Rutgers, University in New Jersey,
neuroscientists Paula Tallal and Steve Miller had begun to suspect that
Specific Language Impairment (a general term that includes dyslexia) might
reflect a problem not with recognizing the appearance of letters and words
but, instead, with processing certain speech sounds-fast ones.
Dyslexics, Dr. Tallal thought, have some brain impairment that prevents
them from hearing staccato sounds like 'b', 'p', 'd' and 'g', 'which burst
from the lips and vanish in just a few thousandths of a second. Since
learning to read involves matching written words to the heard language,
it's no wonder that a failure to hear certain sounds impairs reading ability.
When Dr. Tallal discussed her theory at a science meeting in Santa Fe, you
could almost see-the light bulb go off over Dr. Merzenich's head. His
experiments on monkeys, he told her, had implications for her ideas about
dyslexia. Dyslexics might become better readers, he said, if their brain
could be rewired to hear staccato phonemes --something that could be done
by harnessing the power of neuroplasticity.
To find out if the brains of young dyslexics could be rewired, and if that
rewiring would help them read better, the Rutgers scientists recruited
about a dozen kids and designed an experiment. One of Dr. Merzenich's
colleagues, meanwhile, wrote software that slows down staccato phonemes,
stretching out the interval between 'b' and 'aaah' in 'baa', for example.
To everyone else, the processed speech sounds like someone shouting
underwater. But to the dyslexic children, the scientists hoped, it would,
sound like 'baa' -- a sound they had never before heard clearly. When Dr.
Tallal listened to the processed speech, she was so concerned that the kids
would be bored out of their minds listening to endless repetitions of words
and phonemes, that she dashed out for a supply of Cheetos. She figured her
team would have to bribe the kids to stick with the program.
And so began Camp Rutgers. For 20 days one summer, 22 kids age five to
nine played CD-ROM games structured to alter the brain. One game asked the
child to 'point to rake' when pictures of a lake as well as a rake were
presented, or to click a mouse when a series of the spoken letter 'g' was
interrupted by a 'k'. To train the brain to hear target sounds, the
computer voice stretched them out, intoning 'rrrake' and 'ddday' and 'bbbay.'
To ease the monotony, the scientists offered the kids snacks and puppets,
frequent breaks and even handstand demonstrations. Steve Miller recalls:
"All we did for hours every day was listen. We couldn't even talk to the
kids; they got enough normal speech outside the lab. It was so boring that
Paula had to give us pep talks and tell us to stop whining. She would give
us a thumbs-up for a good job-and we'd give her a different finger back."
After a few months of training, all the children tested at normal or above
in their ability to distinguish sounds. Their language and reading ability
rose two years, something no other dyslexia program had achieved. Although
the research did not include brain scans, it seemed Fast ForWord (as the
software was called) was doing something more dramatic than your
run-of-the-mill educational CD: It was rewiring brains. "You create your
brain from the input you get," says Paula Tallal.
At first that was only speculation. Critics of Fast ForWord said the
system was being rushed to market before its claims had been proved. The
contention that Fast ForWord reshapes the brain was the target of the most
vituperation. Michael Studdert-Kennedy, past president of the Haskins
Laboratories, a center for the study of speech and language at Yale
University, told the New York Times in 1999 that inducing neuroplasticity
was "an absurd stunt" that would not help anyone learn to read.
Yet a year later, researchers reported compelling evidence to the contrary.
Using brain-scan technology called functional Magnetic Resonance Imaging
(fMRI), John Gabrieli of Stanford University compared the brains of
dyslexics before and after Fast ForWord. He found exactly what the
skeptics said he wouldn't: In dyslexics whose language comprehension had
been improved, the brain's left prefrontal region showed more activity
after training. Hearing the drawn-out sounds apparently induced this
region, impaired in dyslexics, to do its job of processing staccato sounds.
As evidence accumulated that changes in the sensory information reaching
the brain can profoundly alter the cortex, an obvious question arose: Can
the mind itself change the brain? Can mere thinking do it? Dr.
Pascual-Leone, now at Harvard University, provided a preliminary answer,
with an experiment that has not received nearly the attention it deserves.
He had one group of volunteers practice a five-finger piano exercise, and a
comparable group merely think about practicing it. This second group
focused on each finger movement in turn, essentially playing the simple
piece in their heads, one note at a time.
Actual physical practice produced changes in each volunteer's motor cortex,
as expected. But so did mere mental rehearsal. In fact, as big a change
as the physical practice. Like actual movement, imagined movements change
the cortex. Merely thinking about moving produces brain changes comparable
to those triggered by actually moving.
The existence, and importance, of brain plasticity are no longer in doubt.
The brain is dynamic, and the life we lead leaves its mark in the complex
circuitry of the brain -footprints of the experiences we have had, the
thoughts we have thought, the actions we have taken. The brain allocates
neural real estate depending on what we use most: the thumb of a videogame
addict, the index finger of a Braille reader, the analytic ability of a
chess player, the language skills of a linguist.
But the brain also remakes itself based on something much more ephemeral
than what we do: It rewires itself based on what we think. This will be
the next frontier for neuroplasticity, harnessing the transforming power of
the mind to reshape the brain.
>>>>>
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Keith Hudson,6 Upper Camden Place, Bath BA1 5HX, England
Tel:01225 312622/444881; Fax:01225 447727; E-mail: [EMAIL PROTECTED]
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