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from Howie Firth to the minciu_sodas_en yahoo e-forum
Paper on which Howie’s remarks followed
After the Double Helix: Unraveling the Mysteries of the State of
Being By MARGARET WERTHEIM
Published: April 13, 2004, New York Times
SAN DIEGO - Sitting at lunch on the patio of his home here one muggy
day last June, Francis Crick was expounding on the mind-body problem and the
thorny subject of the human "self."
Where is the line between mind and matter? he asked. Aside from
the neurons in our brains, the human body contains tens of millions of neurons
in the enteric nervous system, which extends into the stomach and intestines.
"When you digest your lunch is that you?" Dr. Crick asked.
Body and mind are the twin problems around which Dr. Crick's life
has spiraled, much like the double helix structure of DNA that he and Dr. James
D. Watson are famous for discovering half a century ago. Though his research on
"the molecule of life" is what he is best known for, in his 28 years
at the Salk Institute for Biological Studies, his work has focused on the mind,
and in particular the question of consciousness.
Until recently, that subject was viewed with deep suspicion in
scientific circles, but Dr. Crick has led a campaign to make it acceptable.
These days it is even fashionable. While some philosophers claim that
consciousness is a phenomenon outside the purview of material science, Dr.
Crick dismisses such arguments with the imperious confidence that is part of
his legend. "The mechanism is the important part; the rest is just playing
with words," he said in a recent interview.
Dr. Crick's career has been characterized by celebrated
collaborations, and for the past decade he has been working with Dr. Christof
Koch, a professor of computation and neural systems at the California Institute
of Technology. Together they have developed a framework, which Dr. Koch has
spelled out in his new book, "The Quest for Consciousness: A
Neurobiological Approach."
In late March, Dr. Crick and Dr. Koch sat down in San Diego to
discuss their recent work. Now 87 and suffering from the advanced stages of
cancer, Dr. Crick has been put on a new regime of chemotherapy. Yet in spite of
the toxic cocktail, he seems as sharp as ever, tossing out answers like
perfectly aimed darts. Almost from the start of his career, he was obsessed
with two problems: "the borderline between the living and the nonliving
and the nature of consciousness." In the late 1940's, after a notable
career as a physicist in the British Admiralty, he began to investigate the
first topic by studying the structure of proteins. In 1951, he teamed up with
Dr. Watson to determine the structure of DNA. Few scientists believed DNA
carried the genetic code, but Mr. Crick - he did not get his doctorate until
1954 - and Dr. Watson were convinced that it did. Their epoch-making paper on
the double helix was published in 1953, and in 1962 they won the Nobel Prize in
Physiology or Medicine, with their colleague Dr. Maurice Wilkins. Dr. Crick
next collaborated with Dr. Sydney Brenner, and together they worked on the problem
of how the genetic code translated into proteins that build organisms. By the
end of the 60's, the foundations of molecular biology were well understood, and
Dr. Crick was eager to go to his next great question. In 1976, he moved to the
Salk Institute, reinventing himself as a neuroscientist. Since then, Dr. Crick
has been a tireless champion of the brain. In a 1979 editorial in Scientific
American, he argued that the time had come for science to take on the
previously forbidden subject of consciousness. In his 1994 book "The
Astonishing Hypothesis: The Scientific Search for the Soul," he went
further. "You," he wrote, "your joys and your sorrows, your
memories and your ambitions, your sense of personal identity and free will, are
in fact no more than the behavior of a vast assembly of nerve cells and their
associated molecules." He outlined an empirical approach focusing on
visual consciousness.
His ideas have formed the inspiration for Dr. Koch's research at
Caltech: the goal is to find "the neural correlates of
consciousness," or N.C.C.'s - the neuronal states and processes associated
with conscious awareness. Dr. Koch and his graduate students are finally
gaining experimental evidence for what Dr. Crick had termed the "awareness
neurons" that enable us to see.
Dr. Crick's ideas, along with those of another Nobelist, Dr.
Gerald M. Edelman, helped shift the direction of neuroscience. These days,
papers on the neural correlates of consciousness are increasingly commonplace,
though Dr. Nancy Kanwisher, a neuroscientist at the Massachusetts Institute of
Technology, noted that still "very few neuroscientists directly discuss
the N.C.C.'s." But even Dr. David Chalmers, a philosopher at the
University of Arizona and a leading critic of the materialist approach to mind,
acknowledges the value of the work of Dr. Crick and Dr. Koch. "Everyone
agrees now that there are systematic processes happening in the brain that must
correlate with awareness," he said. Many of Dr. Koch's experiments are
aimed at teasing out what the brain is registering beneath the radar of
conscious awareness. One tool for studying this is trace conditioning. Using
it, a subject is presented with two consecutive stimuli - say an image and a
mild electric shock - separated by a delay. After a period of training,
subjects begin to anticipate the shock (measured by a rise in skin conductance
on their palms) when they see the image. Using M.R.I., Dr. Koch's team has
shown that in trace conditioning, an area of the brain known as the anterior
cingulate cortex is activated. They have found that when they remove this area
from mice, the creatures cannot be trace conditioned, causing Dr Koch to
speculate that this area of the brain is critical for consciousness. Dr. Koch
notes that the advent of M.R.I. has also made it possible to see which parts of
the brain are active during a "percept" - as when someone sees a
face. Dr. Kanwisher has shown that there are specific parts of the brain that
register awareness of faces and objects. A small group of patients with
epilepsy are letting scientists get an even more intimate look at the brain.
Working with Dr. Itzhak Fried, a neurosurgeon at the University of California,
Los Angeles, graduate students of Dr. Koch's are exposing the patients to
images and checking the activity of individual neurons as recorded by
electrodes implanted in their brains. Dr. Koch's team is looking for neuronal
evidence of "change blindness" in these patients. An array of four
photographs is flashed on a screen, followed about a second later by another
array in which one of the images has changed. "It can be surprisingly
difficult to consciously see such changes," Dr. Koch said, though evidence
suggests that neurons may be registering them.
Not everyone is convinced that understanding the neural correlates
will explain awareness. "There is a difference between correlation and
explanation," Dr. Chalmers said. "The question is, once we have these
neural correlates, What do we do with them? I don't think the N.C.C.'s is a final
theory."
In tackling consciousness, Dr. Crick and Dr. Koch have reframed
the central question. Traditionally the problem has been cast in terms of
subjectivity. How is it, for example, that when someone sees red (which
physically speaking is electromagnetic waves of a particular frequency) there
is also a subjective feeling of redness? The "redness" of red and the
"painfulness" of pain are what philosophers refer to as qualia. The
gap between the objectivity of material science (the electromagnetic waves) and
the subjectivity of human experience (the qualia) has led some philosophers to
conclude that this chasm cannot be bridged by any materialist explanation.
Rather than getting bogged down in the depthless ooze of qualia, Dr. Crick and
Dr. Koch sidestep the issue. Instead of asking the philosophical question of
what consciousness is, they have restricted themselves to trying to understand
what is going on at the neurological level when consciousness is present.
While many scientists assume that consciousness is a global
property of the brain - "a gestalt phenomenon" - Dr. Koch and Dr.
Crick say they believe that only a few neurons are responsible at any given
moment. Of the 50 billion or so neurons in the brain, Dr. Crick says that
perhaps only tens of thousands, or even a few thousand, give rise to the
feeling of conscious awareness. "We believe it is essentially a local
phenomenon," he said.
That position is certainly contentious. "The idea that there
is a special population of neurons that mediate awareness is a minority
view," Dr. Kanwisher noted.
Dr. Crick says he is convinced that the origin of consciousness is
a solvable problem, albeit complex.
He drew an analogy with another phenomenon once attributed to
transcendent powers: "People think the brain is mysterious but not the
weather. Why is that?" In some ways, he suggested, the brain may be less
enigmatic than the weather, because "we don't yet have a clear
understanding of how raindrops form but we do know how individual neurons and
synapses work."
The elucidation of the double helix ushered in the age of
molecular genetics, which has now given rise to the vast applications of
genetic engineering. Elucidating consciousness could have similarly portentous
results, Dr. Koch suggests.
One potential application, he says, is some kind of instrument for
measuring its intensity, perhaps a "consciousometer."
Anesthesiologists might use it to determine when a patient under sedation is
truly out. But in his book, Dr. Koch also raises the possibility of more troubling
uses, including measuring the awareness levels of severely retarded children
and elderly patients with dementia.
Or, he asks, "How do we know that a newborn baby is
conscious?" Perhaps consciousness is something that doesn't begin at
birth, he said, but gradually emerges.
"This research is going to pose enormous legal and ethical
questions," Dr. Koch acknowledged in the recent interview. "I'm not
convinced that people want to know how consciousness works," he said.
"They feel cast out of the world of meaning."
Having solved one of the basic mysteries of life here on Earth,
Dr. Crick seems happy to skewer any notions of a life beyond. For him, the most
profound implication of an operational understanding of consciousness is that
"it will lead to the death of the soul." "The view of ourselves
as `persons' is just as erroneous as the view that the Sun goes around the
Earth," he said. He predicted that "this sort of language will
disappear in a few hundred years." "In the fullness of time," he
continued, "educated people will believe there is no soul independent of
the body, and hence no life after death."
http://www.nytimes.com/2004/04/13/science/13CRIC.html?pagewanted=3n
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