快猫短视频

IN a recent book of interviews by the British broadcaster Melvin Bragg, Susan
Greenfield, a prominent neuroscientist, makes a surprising admission. She
reveals that she is a fan of Sigmund Freud, whose theory of psychoanalysis has
been derided by some as the epitome of pseudoscience. 鈥淚 am quite unusual,
perhaps, as a neuroscientist, in finding Freud inspirational,鈥� she says.

Actually, Greenfield鈥檚 liking for Freud is shared by many other high-profile
neuroscientists, notably Eric Kandel, a memory researcher at Columbia University
in New York, the Nobel laureate Gerald Edelman of the Neurosciences Institute in
La Jolla, California, and Floyd Bloom, editor of the journal Science.
How is it that psychoanalysis, once described as 鈥渢he treatment of the id by the
odd鈥�, has retained the respect of scientists who are supposed to know
better?

The answer is not that psychoanalysis has been empirically validated: even
its admirers admit that at best the evidence is weak for psychoanalysis as
either a theory of, or therapy for, the mind. No, the reason Freudian ideas
persist is that science has failed to provide an obviously superior explanation
of the psyche or treatment for its disorders. Despite the best efforts of an
army of researchers, the E = mc² of the mind remains as elusive as
ever.

Outwardly, the picture has never looked brighter. Governments spend ever more
billions on mind and brain research while journals and conferences dealing with
neuroscience multiply like rabbits. Researchers forever seem to be on the brink
of uncovering the key to aggression, depression, addiction, schizophrenia, even
consciousness itself. The problem is, they never get there. A century鈥檚 worth of
investigations has not produced a paradigm powerful enough to push Freud off his
pedestal.

This lack of progress is reflected in the status of treatments for mental
illness. Few therapists practise classic Freudian psychoanalysis any more: it
has yielded to other, supposedly more 鈥渕odern鈥� psychotherapies, such as
cognitive-behavioural therapies. But evaluations indicate that all these
鈥渢alking cures鈥� are roughly as effective鈥攐r ineffective. Proponents of
psychiatric drugs such as Prozac claim that they represent a tremendous advance
in the treatment of depression, anxiety and other common emotional ailments. In
fact, comparisons of psychotherapy with antidepressants suggest that the two
produce roughly the same outcome.

Even neuroscience, the field best equipped to kill off Freud, has not made
its punches count. Neuroscientists have acquired an astonishing ability to probe
the brain with microelectrodes, magnetic resonance imaging, PET scans and other
tools. But so far, there has been virtually no payoff in diagnosing and treating
mental illness. And what few unified theories of the brain and mind have emerged
to rival Freud, neuroscience has failed to winnow out.

There are the connectionists, for instance, who hold that the mind is encoded
in the interconnections between nerve cells, with the environment all powerful
in shaping those connections. Then there are the Darwinian psychologists who see
the psyche as a toolbox of rigid skills and instincts bequeathed to us by
natural selection; the dynamicists, who look to the likes of chaos theory for
inspiration; and even a small band of scientists who think the mind may
ultimately be explained by mysterious quantum effects in the brain. Is it any
wonder Freudianism lives on when its rivals so often look like warring academic
cliques?

This is not to say that neuroscientists are failing to make empirical
discoveries. Far from it. Their journals positively overflow with results
detailing how neurons, receptors and neurotransmitters work, how mice deprived
of this or that gene are unusually slow learners or fearful or aggressive or
more likely to get hooked on alcohol. And thanks to brain imaging, scientists
are learning more and more about where things happen in the human
brain鈥攚hich regions have increased or reduced activity when we fall asleep
and dream, listen to Mozart, play chess or even view pornography. Unfortunately,
it鈥檚 seldom obvious what happens in any of these regions to actually produce the
sensations and thoughts of which our minds are made.

Arguably the most important discovery from neuroscience so far is that
different regions of the brain are specialised for different functions. For
instance, the visual cortex contains one set of neurons dedicated to orange-red
colours, another to objects with high-contrast diagonal edges and still another
to objects moving rapidly from left to right. Or take memory. As recently as the
1950s, many scientists believed memory was a single鈥攁lbeit
versatile鈥攆unction. Since then experiments have revealed there are many
types of memory, each located in its own region of the brain.

As neuroscientists keep subdividing the brain, one question looms ever
larger: how does the brain integrate the workings of its highly specialised
parts to create the apparent unity of perception and thought that constitutes
the mind? This conundrum is sometimes called the binding problem. I prefer to
call it the Humpty Dumpty dilemma. Like a precocious eight-year-old tinkering
with a radio, neuroscientists excel at taking the brain apart, but they have no
idea how to put it back together again.

The more baffling a scientific mystery is, the more theories there are for
solving it, and the Humpty Dumpty dilemma is no exception. A leading hypothesis
holds that the different components of perception funnel into 鈥渃onvergent
zones鈥�. One such zone is thought to be the prefrontal cortex, a thin sheet of
tissue lying atop the brain. The prefrontal cortex underpins what is called
working memory. Like the RAM on a computer, which makes information available
for instant use, working memory allows us to maintain the thread of a
conversation, read a book, or perform simple arithmetic in our heads.

Patricia Goldman-Rakic of the Yale University School of Medicine, an
authority on working memory, believes that it is the key to solving not only the
binding problem but also the riddles of consciousness and free will. Actually,
her research has highlighted rather than solved the Humpty Dumpty dilemma.
Goldman-Rakic and others have shown that working memory is itself composed of
many parts. One set of neurons in the prefrontal cortex stores short-term
information about an object鈥檚 location; other sets correspond to features such
as size, shape and colour.

Might neuroscience be delivered from its current impasse by some genius who
will discern patterns and solutions that have eluded all others? Other fields
provide some justification for this hope. During the 1950s, particle physics was
mired in a crisis that resembled the plight of neuroscience. While accelerators
seemed to generate an exotic new particle almost daily, theorists had no idea
how to organise the welter of findings into a cohesive theory. Then a young man
called Murray Gell-Mann showed that many of these strange particles were made of
a few more fundamental particles called quarks. Out of chaos, order.

Core mysteries

But in terms of sheer complexity, particle physics is a child鈥檚 game鈥攁
10-piece jigsaw puzzle of Snow White鈥攃ompared with neuroscience. Freud鈥檚
ability to construct a unified theory of human nature a century ago owed a lot
to science鈥檚 ignorance during his era. Anyone hoping to construct such a theory
now must cope with an astronomical number of findings, many of them with
contradictory implications. When it comes to the human brain, there may be no
unifying insight that transforms chaos into order.

Nobody has come close to solving such 鈥渃ore鈥� mysteries as consciousness, the
self, free will and personality. According to the Harvard psychologist Howard
Gardner, these conundrums 鈥渟eem particularly resistant to decomposition,
elementarism, or other forms of reductionism鈥�. He suggests that mind scientists
should adopt a more 鈥渓iterary鈥� style of investigation鈥攖he style
exemplified by Freud.

The biologist Lewis Wolpert of University College London retorts that any
discussion of neuroscience鈥檚 limits is grossly premature because the field is
鈥渏ust beginning鈥�. Actually, the roots of neuroscience run as deep as those of
many other fields of science. Luigi Galvani showed two centuries ago that nerves
produce and respond to electric current, and around the same time Franz Gall
proposed the first modular-mind theory, phrenology.

The claim that neuroscience is 鈥渏ust beginning鈥� is based not on the field鈥檚
actual age but on its slow progress. Wolpert acknowledges as much in his book
The Unnatural Nature of Science. Mind-related research is still in a
鈥減rimitive鈥� state, Wolpert wrote, compared with fields such as nuclear physics
and molecular biology. As evidence, Wolpert cites the fact that it鈥檚 not yet
possible 鈥渢o do any experiment at the level of brain function or neurophysiology
which would contradict psychoanalytic theory鈥�.

I agree with Wolpert about the primitive state of neuroscience. The question
is, how much progress can we expect in the future. Most scientists are
optimistic. The lack of progress thus far, they contend, means that great things
await us. In other words, past failure predicts future success.

This is not so much an argument as an expression of faith. I fear that, given
their poor record, neuroscience and other fields addressing the mind might be
bumping up against fundamental limits of science.

On the other hand, the fact that the mind may be in certain respects
irreducible means mind-science may last forever. The problems posed by the human
mind are so important, pragmatically and intellectually, that scientists will
surely never stop trying to solve them. Inner space is science鈥檚 final鈥攁nd
possibly eternal鈥攆rontier.