THE operations of the cerebral cortex that enable us to think, reason and
create are complex and still poorly understood. One way forward is to use
models, and a number have emerged recently as new tracing, recording and imaging
techniques have generated a torrent of data on brain functions. William
Calvin’s, outlined in The Cerebral Code, is one of the more persuasive I
have come across.

His theory is rooted in the anatomy and physiology of cortical neurons and
circuits. Onto this physical base he grafts the principles of the Darwinian
evolutionary process to illustrate the seconds-to-minutes operations among
populations of neurons. He considers that these principles are used particularly
for shaping and improving the processes responsible for recognition and recall
memory, and the higher intellectual functions we call the mind.

The human cortex is a sheet of tissue only a few millimetres thick, although
its folds make it seem more substantial. Groups of neurons with similar
responses are organised into columns, and columns with a common input tend to
cluster into macrocolumns.

Calvin sees each macrocolumn as a hexagonal array representing a particular
spatiotemporal pattern of neuronal activity. Strong patterns will be copied, or
cloned, into neighbouring hexagons, and the more clones a pattern produces, the
more likely it is to control behaviour at that instant. In a vivid musical
analogy, Calvin likens each hexagon to a keyboard, and the spatiotemporal
pattern to a melody. The more hexagons producing the same melody, the more
likely this choir is to drown out other contenders for attention.

As the pattern is copied, variants may arise that will compete with the
parent for limited workspace. Calvin draws parallels with island biogeography to
show how the cortical mechanisms of excitation and inhibition could produce
barriers that might allow minority patterns, the basis of new ideas, to succeed.
The competition will also be influenced by the environment, which includes
levels of modulatory neurotransmitters and peptides as well as fading patterns
previously recorded in the hexagons. I particularly like Calvin’s analogy of
ghosts of information left when a blackboard is cleaned.

Calvin then shows how the basic model can be applied to problems such as the
sequences needed for body movements and in language, making associations,
imagining, and thought pathologies. Finally, he goes for gold with a thought
experiment, testing his theory on consciousness and a mechanistic outline for
Universal Grammar.

These highly speculative applications are certainly provocative.

Of course, this type of model is only as good as the testable predictions it
makes. Automatic gain control is a potential winner that, if found in the
nervous system, would add considerably to the mechanisms known to modulate
neuronal circuits. One reservation, though, is that little account is taken of
the feedback, “top-down” connections in the cortex, which may continuously
modify the tunes the hexagons play, or of the loops linking the cortex with
subcortical systems, which anchor the cortex’s operations in the body’s
emotional life.

My other concern is more conceptual. When modelling decision-making processes
(see “Many neurons make light work?”, New �Ӱ�ԭ��, 7 August 1993,
p34), we found that specific neural operations may simply be part of the
behaviour of an attractor network. Because thinking in multidimensional phase
space is difficult, we need metaphors like Calvin’s hexagons to help us to
understand what the network does. My hunch is that these metaphors do not
represent discrete operations, but will be found to emerge from the interactions
of the cortical network.

Years ago, Calvin left a promising academic career for the freedom of
travelling the brain’s landscape—a brave choice which provided an
opportunity for developing a vision that is now all too rare. Right or wrong,
his ideas should stimulate many to think more broadly about the dynamic
processes of the cortex, which are rarely mentioned in neuroscience texts. My
initial frustration with concepts that are implicit rather than explicit was
overcome by Calvin’s synthesis of ideas from many fields. I recommend reading
this book more for its range than for the details of the model. I feel sure that
Calvin’s thinking about the cortex will continue their provocative
evolution.

Reading through the essays that introduce the 11 sections, I was reminded of the excitement I felt as a young postdoc in the early 1970s when I encountered the Neuroscience Study Program. Like that book, The Cognitive Neurosciences gives a broad overview of a newly emerging field, tracing its roots, examining its present condition and speculating on prospects for future growth.

The 11 section editors and the authors of the 92 chapters are among the leaders in the field and their enthusiasm shines through the text. Perhaps this is because they came together for three weeks in the summer of 1993 to discuss and revise their chapters. This would explain, too, why the book has a coherence unusual in edited volumes, especially one of this magnitude.

Cognitive neuroscience is the attempt to characterise how the processes of the brain give rise to mind – to perception, cognition, memory, thought and, ultimately, creativity. It has been developing as a discipline for the past ten or so years, growing out of a convergence of two older subjects: cognitive psychology and classical neurophysiology. The former had little interest in brain mechanisms, preferring to treat the brain as a black box, while the latter sought to explain brain mechanisms but was little concerned with how they served behaviour or the mind.

Cognitive neuroscience also draws heavily on the work of neurologists and neuropsychologists with brain-damaged patients but, at least in the view of this book, does not include pathological malfunctions such as depression or schizophrenia.

Undoubtedly, brain imaging has played a large part in the development of cognitive neuroscience, affording us for the first time glimpses of the human brain in action. The knowledge gained from many years of experiments with animals can now be related much more directly to humans. Scanning, too, has played a part by allowing us to analyse the effects of brain lesions on behaviour: the extent of the lesion can now be described accurately while the patients are still alive and their behaviour studied.

Imaging and lesion data are the main ways at present for working out the mechanisms underlying the uniquely human (as far as we can tell) abilities of language, thought and mental imagery. The techniques are still in their infancy and the results somewhat crude, but we can expect an explosion of increasingly refined information from them in the next few years.

Of course, the book deals not only with studies of the human brain but also the animal studies that form the jumping-off point for human investigations. The focus is a broad one, setting the work on higher brain functions in the framework of sensory and motor systems, plasticity and development that are the meat of neurosciences. Not only is this where the most telling advances have been made in the past few years, but knowledge of the inputs and outputs of the brain is an essential component of understanding memory, language, thought and mental imagery.

Emotion has a section to itself, a signal that at last the role of the emotions in the life of the brain is being taken seriously. For too long the emotions have been considered too messy for scientific study and all the emphasis has been on the outward-looking, so-called objective processes.

A recurring theme is how far information gained from other species is relevant to humans. A section entitled “Evolutionary perspectives” makes clear the strengths and weaknesses of the comparative approach. Evolution from a common ancestor means that related species inherit a common ground plan; however, the specialisations that give each species its uniqueness interact with the ground plan in different ways.

Neuroscientists tend to be unaware of or to ignore the second, but they do so at their peril. Language, for example, has not simply been superimposed on the ancestral ape brain structure, but has provided humans with another dimension for manipulating information. Information-based systems in the human brain, particularly memory, are thus unlikely to be just an elaboration of that in the macaque monkey (the favourite subject for research) – new mechanisms are to be expected.

There are sections covering attention and consciousness as well as the topics already mentioned. Every section forms a self-contained unit, with an introduction by the section editor that puts the chapters in perspective. The chapters themselves are dense, scholarly review articles written for practising neuroscientists. They will be a challenge to senior undergraduates and doctoral students but contain much meat for essays and theses. References run up to 1993, with a few from 1994.

In keeping with the book’s aim to show the broad sweep of the cognitive neurosciences, some chapters are entirely theoretical, others mix theory and practice, while still others review experimental work. Some have a historical perspective, especially where there has been controversy; others provide just enough background information to underpin the current position or debate. Open questions are clearly stated and speculation encouraged, so the book shows not only the state of the art but has a forward impetus too.

And the prospects? To judge by these accounts, the subject is a sturdy young plant about to burst into bloom. Some areas are ahead, while those dealing with human specialities only just have the buds showing. But the emerging picture seems to be that many of our unitary concepts, such as memory, language and even consciousness, can be subdivided, that these subdivisions are or will be amenable to experimental analysis, and that they reflect the way the brain is organised into many interacting modules. Defining those modules may be well under way, but understanding how they interact is still in its infancy.

This is a book to pick up and dip into repeatedly – the only pity is that it is so heavy to pick up.

The woman, known as S. M., has a rare disease which has damaged the amygdala region of her brain. She also has problems perceiving other “negative” emotions, such as anger and surprise, if expressed at the same time.

The amygdala is an almond-shaped structure at a crossroads in the brain’s circuitry: it links the cortex, which is responsible for conscious thought, with regions of the brain that control the body’s emotional responses. �Ӱ�ԭ��s knew that the amygdala helps regulate reactions associated with strong emotion – such as quickened heart rate and sweating. But what exactly does it do?

Brain researchers determine the function of a part of the brain by studying people whose brains are damaged in that region. But patients with damage to the amygdala alone are very unusual, according to Antonio Damasio of the University of Iowa, who led the team that made the new discovery.

S. M. first turned up at a hospital suffering from epilepsy. Later, when her doctors looked for the root of the problem using magnetic resonance imaging, they found that her amygdala was destroyed. This was the result of Urbach-Wiethe disease, which deposits calcium in the amygdala. With S. M.’s consent, the Iowa researchers subjected her to a battery of psychological tests devised by Damasio’s colleague Ralph Adolphs, asking her to say what emotions were being expressed by the people pictured in a series of photographs.

S. M. failed what Damasio calls “the Doris Day test”. “When we showed her a film clip of Doris Day screaming, she asked, ‘What is she doing?’,” he says. In fact, S. M. was baffled by any picture showing a fearful expression. She also had problems deciphering mixtures of negative emotions, such as anger and surprise. By contrast, she had no difficulty with “positive” emotions such as happiness. She was also perfectly able to recognise familiar faces (Nature, vol 376, p 669).

These results, says Damasio, indicate that the amygdala has a pivotal role in linking frightening signals from the environment with the body’s fear responses. Fear is universally important for survival in animals, Damasio notes, so it is reasonable that a special brain system has evolved to deal with it. The amygdala also seems to help us respond correctly to complex mixtures of negative emotions expressed by other people. Because she often fails to recognise criticism or aggression, S.M. has difficulty interacting socially.

Positive emotions seem to be processed in another region of the brain. Just where is a mystery. “We’ve never seen a patient who can’t recognise a happy face,” says Adolphs.

The story of a discovery usually makes exciting reading but the history
of a whole field of science is a project of much greater magnitude. When
that field is understanding how our own brains work, the project is gargantuan.
It is likely that our early ancestors, the australopithecines, appreciated
the vital role of the brain. Certainly there is evidence that people in
Neolithic times had some understanding of brain function.

There are many ways a history of such a huge subject can be written,
but Stanley Finger has chosen to focus on the localisation of functions
in the human brain for his splendid book, tracing the development of ideas
from prehistory to the early 20th century.

The book is packed with facts, and Finger has woven clinical observation
and experimental work on animals into a fascinating story that will appeal
to anyone with some knowledge of brain structure and function. Such a history
helps to anchor the present explosion of discoveries in the neurosciences
firmly in the achievements, not to mention errors, of the past.

The concept of attributing functions to particular parts of the brain,
now a fundamental tenet of neuroscience, took a long time to establish.
By the 2nd century AD, the influential Roman physician Galen had started
trying to identify which parts of the brain perform which functions. But,
until the end of the Renaissance, the ventricles, the internal cavities
of the brain, were thought of as stores for the ‘animal spirits’ – the highest
form of the vital spirits responsible for life – and the seat of the higher
functions of imagination, intelligence and memory. Only in the 17th century
were these functions firmly placed in the tissue of the brain and slowly,
through observation and experiment in the 18th and 19th centuries, functions
became more and more precisely assigned to structures.

Localisationists still did not have it easy: the popular 19th-century
fad for phrenology brought the whole idea into disrepute. It took the reputation
of the distinguished French neurologist, Paul Broca, who described an area
of cortex associated with production of speech in 1861, to make localisation
respectable again. Even into the 20th century, though, the idea has had
its opponents.

The book starts with a broad overview of the main developments, debates,
dissensions and battles in this story. Then follows a more detailed history
of all the major functions and many malfunctions of the brain, from the
individual senses to intellect, memory and language, finishing with the
development of ideas about cerebral dominance. The chapt-ers are self-contained,
so they can be used as background reading for students, although this leads
to repetition.

The book’s coverage of the subject ends, except for a few topics, at
the period between the wars, and Finger points out many questions that remain
unresolved today. In several places, though, I would have loved some explanation
or speculation as to why observations were made that later turned out to
be erroneous.

At the end we are treated to a survey of therapies up to 1918. This
is not for the faint-hearted. Some of the potions used to treat paralysis
and convulsions in the past were revolting beyond belief.

Fashion played a large part in therapies: after the Italian physiologist
Luigi Galvani had demonstrated in 1791 that nerves conduct electricity,
electric shock was used for almost every condition in the first half of
the 19th century. But as localisation became more refined at the end of
the last century, and with it an understanding of the functions of particular
regions of the brain, symptoms could be used to identify the site of tumours
and so modern neurosurgery was born.

Throughout, Finger provides lively thumbnail sketches of the protagonists,
richly illustrated. He gives not only a flavour of their personalities but
also the religious, social and political context that shaped their ideas.
He leaves us in no doubt that the brain sciences, which bring us closest
to the existential questions about life, have always been heavily influenced
by contemporary culture. Even today we have claim and counterclaim about
‘gay brains’. Throughout the book we are reminded how difficult it has always
been to achieve objectivity when studying the brain.

For me, this is an important reason for reading a history of neuroscience.
Perhaps this hindsight will help those of us who work on the brain to maintain
humility and awe in our struggles to understand its complexities. The book
is a must for anyone researching brain function or treating diseases of
the nervous system; highly recommended to anyone fascinated by how our brains
work.

Jennifer Altman is a research consultant and writer, specialising in
the neurosciences.

In his preface, Roy Porter claims this dictionary ‘is designed to spell
out and make accessible the multi-dimensional nature of science as thought
and activity’. But is a dictionary the best way to convey the excitement
behind this concept? Its alphabetical nature makes it difficult to follow
trends. I suspect that most readers, like myself, use a dictionary in two
ways: as a quick way to gain information about a specific item, and for
random browsing.

So does this large volume succeed as a dictionary? Is it representative
and accurate? It is the amalgamated second edition of six volumes on the
separate disciplines, first published in the mid-1980s. It would be fine
if the publisher had stuck to updating the entries it had then, and called
it a historical dictionary. But the revision simply does not reflect the
developments of the past twenty years or provide a ‘Who’s Who’ of modern
science. Even many of the entries about those still living or recently
dead seem to stop short at about 1980. Few whose careers have peaked in
the past twenty years have made it past this cut-off date, and those are
mostly people who are distinguished as popularisers of science.

To cover five thousand years of science in only 1200 entries is tough.
Apart from being dead, to get included it clearly helped to be male (about
one in fifty entries are women, reflecting the invisibility of women in
the history of science); to have won a Nobel prize (at least before 1980);
to have lived and worked in Europe, particularly in Britain or Germany;
and to have been immortalised in the name of a law, principle or structure.
This last criterion does not seem to extend to institutions, for neither
Sir Henry Wellcome, founder of the Wellcome Trust, nor Chaim Weizmann, after
whom the Israeli Weizmann Institute of Science is named, are included –
although both were distinguished scientists and industrialists, as well
as philanthropists. I can think of a dozen British biologists who have as
much claim to inclusion as some of those whose names do appear.

The entries mostly fail to fulfil Porter’s wish to provide a dynamic
picture of scientists at work. I found them dry, the regimented format irritating
and tending to repetition, and for me they failed to capture the spirit
and intellectual excitement of people with whom I am acquainted. Accuracy
worries me too. In some accounts, where I know the science, the explanations
are rather facile. By chance, I found one entry that was badly off beam
– that for J. W. Sutton-Pringle, who was always known as J. W. S. Pringle.
Apart from the name, the entry does not mention that he became professor
of zoology at Oxford in 1962 and his chief contribution was in muscle biophysics
– only his earlier work on insect flight is cited. I can only hope that
entries in other fields are more reliable.

As a historical dictionary, the book has its niche. It includes brief
histories of the major disciplines, a useful glossary and a list of Nobel
prizewinners – up to 1993, this time – and, unusual for a dictionary, an
index. Sad that the editor and publishers didn’t limit their aims when planning
the second edition.

Jennifer Altman is a freelance research consultant and writer specialising
in the neurosciences.

What makes a person creative? Are exceptionally creative people different
from the rest of us in some other way? Howard Gardner established his reputation
by distinguishing seven types of intelligence: ranging from logical-mathematical,
visuo-spatial, musical, linguistic, bodily kinaesthetic, intrapersonal and
interpersonal. He deliberately chose one innovator to represent each type
of intelligence, to test the strength of his findings across a wide spectrum
of achievements: Sigmund Freud, Albert Einstein, Pablo Picasso, Igor Stravinsky,
T. S. Eliot, Martha Graham and Mahatma Gandhi.

The core of the book is made up of short biographies of his magnificent
seven, flanked by analysis. In lively prose, marvellously free of sociological
jargon or psychobabble, Gardner starts by explaining his choices, outlining
his organising principles and listing his criteria. In the thought-provoking
final chapters, he draws conclusions about the creative personality and
its life, and the creative enterprise. Finally, he examines the influence
of these innovators on the development of what he terms the modern era,
roughly the first half of our century.

So what trends emerge from his analysis? Perhaps the biggest surprise
for me was that the special talents of the seven flowered relatively late.
Only Picasso displayed prodigious gifts as a young child – exceptional childhood
accomplishments seem to be a poor predictor of exceptional adult creativity.
All were in their twenties or even thirties before making their breakthroughs.
Nor do innovations come rapidly: the first breakthrough required at least
ten years’ work. For most of them, second and even third innovations, less
radical but more comprehensive than the first, followed at approximately
ten-year intervals.

All, however, maintained a childlike approach to the problems that
absorbed them as adults. Dissatisfied with the established state of the
domain in which their talents lay, their childlike vision helped them to
achieve radical new views.

Marginality is another common theme: some were born marginal, Graham
because of her sex, Gandhi his personality. Eliot and Picasso made themselves
marginal by living in foreign countries and cultures. They all took risks
by setting themselves outside the established canon and so experiencing
isolation and loneliness as they approached their radical breakthroughs.
Several even engineered their lives to increase their marginality and the
risks as their work became accepted.

Two unexpected traits emerge in their personal lives. All required the
emotional and intellectual support of one or more close companions during
the period of their breakthrough, but they also made huge demands on those
close to them. Most sacrificed personal contentment for success in their
creative endeavour – a Faustian pact, as Gardner calls it.

Gardner’s daring enterprise is open to many criticisms, not least over
the people he selected and his operating principles, and in the reading
of the lives. Inevitably there is repetition, which is helpful for keeping
track of the themes and emerging conclusions. I couldn’t help wondering
whether the repetition was brainwashing me into accepting the conclusions.
These sound convincing, not least because Gardner does not force all seven
into his picture but points out where and to what extent each fits the overall
scheme.

I was slightly disappointed that no attempt was made to test whether
these findings help us to understand creative people in general or whether
they apply only to a few titans. I find I can slot creative people I know
into this picture relatively easily, so Gardner may well have uncovered
some fundamental aspects of the creative personality and of the process
of creativity. His discussion will inevitably open up more of this fascinating
territory.

Jennifer Altman is a research consultant and writer specialising in
the neurosciences.

When I began to read this book, I assumed it was a ‘Son of Oliver Sacks’,
a popular account of a neurological phenomenon that reveals something new
about how the brain works. But it is much more than that. By the time I
was halfway through, I realised that behind the racy prose and mild manner,
Richard Cytowic is a revolutionary. He proposes an iconoclastic theory of
how our brains are organised that has far-reaching implications for how
we regard ourselves as human beings. This is an important book that everyone
should – and can read.

The condition that provided Cytowic with the seed for his ideas is syn-aesthesia,
an unusual form of sensory perception. Those who experience it report that
particular sensory stimuli evoke responses normally produced by other senses;
they may feel pointed shapes every time they taste a lemony flavour, or
see high musical notes as pink. Cytowic chanced to meet two people with
synaesthesia during his neurology residency and became determined to discover
a neurological explanation for it. His search is described in the first
part of the book. The surprise that awaited him has led him to debunk the
hallowed supremacy of the cerebral cortex in favour of the limbic system,
the part of the brain that regulates the emotions, and other functions such
as hunger and sexual desire. In the second and, in my opinion, more exciting
section, he explores the consequences in a series of short essays.

Cytowic’s account of his researches into synaesthesia has the flavour
of a trave-logue: using dialogue and anecdote, he describes his explorations
and muses on the contemporary landscape of science, medicine and technology.
These commentaries range from scientific methodology, through the way in
which objectivity can block us from seeing what is really there, to the
dangers of the public perceiving science as equivalent to technology, and
on to how the use of technology, especially in medicine, is devaluing individual
experience.

The startling conclusion to Cytowic’s journey was the discovery that
the cerebral cortex, usually considered the home of sensory perception,
is shut down almost completely during synaesthesia, leaving the limbic system
to dominate brain activity. The limbic system is a circuit of nerve centres
that regulates the internal state of the body, the emotions and memory,
functions that are basic to survival. It selects from the multitude of
incoming sensory data just what is relevant to present needs. Synaesthesia
seems to be an unveiling of the multisensory processing that the limbic
system uses to make these evaluations. Most of us are totally unaware of
this activity because our cortexes are firmly in charge.

The surprise was that the cortex could be so inactive without affecting
his subjects’ high intelligence or normal behaviour. This dramatic finding
brought Cytowic to a view of the brain that is very different from the conventional
one that is dominated by the cortex. I should here declare an interest,
for my own research has led me on a path that converges with his (see ‘Many
neurons make light work?’, New �Ӱ�ԭ��, 7 August), so I am very sympathetic
to his ideas.

The cortex, the thinking part of the brain, is generally assumed to
be the seat of consciousness. Instead, Cytowic draws our attention to the
limbic system and the importance of emotions, or internal information,
in guiding our lives. As well as being a rigorous scientist, he is a Zen
adept. During deep meditation, rational thinking stops and one feels completely
in the present with a sense of universal unity. This, he believes, is when
the limbic, emotional brain is fully in charge – he considers it, and
not the cortex, to be the seat of consciousness.

He is not rejecting the role of the cortex in reasoning, objective assessment
and the assignment of meaning to external events. Rather, the significance
of the limbic system is to provide the subjective information and experience
needed to evaluate the relevance of cortical activity. The two structures
are densely interconnected and work together to make our behaviour fit current
requirements (which includes the memories and plans for the future).

Cytowic strongly attacks the empha-sis on objectivity that stems from
blindly applying the ‘scientific method’ to all aspects of our lives. Elevating
the cortex to prime position has led us badly astray into overvaluing the
roles of objectivity, thought and reason, which are outwardly directed towards
controlling the world. He sees this as the root cause of our neglecting
subjective, emotional, internal information. He argues convincingly that
we are subjective beings and those who think they are thoroughly objective
are deluding themselves. At the door of this objective delusion he lays
many of the ills of our society, from personal unhappiness to wars and the
misuse of world resources. Perhaps it is not surprising that many people
with synaesthesia are artists or writers whose work tends to be more subjective.

His message is a challenging one: pay more attention to internal information;
and let our reasoning and thinking be guided by our subjective experience
instead of trying to force it into an inappropriate objective framework.
This, he feels, is the way to rediscover our spiritual dimension, ‘to touch
the rapture of being alive’.

The book is not without flaws. The puzzle of synaesthesia does not seem
to me fully solved, for why do most synaesthetes experience crossover only
between two senses? In places, crucial steps in the argument are glossed
over, and no sources are given for some of the key pieces of evidence. It
is no excuse that the book is written as a popular account; rather, I think
that such a radical departure from convention requires clear evidence of
its foundations if it is to convince the doubters.

But do not let these small problems distract you from the message. Space
constraints prevent me from giving more than a mere flavour of the richness
of Cytowic’s thinking. With broad sweeps, he outlines a new landscape. The
controversies he will raise will help to clarify the details. Read this
book – and the more objective you think you are, the more open-minded you
will need to be to appreciate it.

Jennifer Altman is a science writer.

THE evolution of the human brain, with its linguistic, cultural, creative
and spiritual capacities, is both a marvel and a mystery. From the available
fossil evidence it seems that in about 2 million years Homo sapiens evolved
from an ape-like ancestor; in this time, the brain enlarged by a factor
of three and a culture developed that included organised societies, art
and rituals.

How and why this happened is largely guesswork. Sadly, brains do not
fossilise and we are left with only the shadowy impressions of the brains
of our ancestors inside their fossil skulls. The fossil record, too, despite
many splendid finds in the past 25 years, is patchy and incomplete. For
the rest, we have to make do by comparing human anatomy, physiology and
pharmacology with that of our nearest relatives, the chimpanzees, and by
studying the cultural remains left by early hominids. Here, too, data are
scarce because chimpanzees are protected and the cultural remains are sparse.

The development of consciousness, creativity and the recognition of
the uniqueness of the self is open even wider to speculation. The debate
over the relationship of the mind to the brain has largely been the province
of philosophers and theologians; neuroscientists are still struggling with
the basic processes of perception and are far from tackling such problems
in any systematic way. But the evidence provided by those unfortunate people
who suffer brain lesions that alter the personality or sense of self is
enough to convince many neuroscientists that the mind is the product of
the brain. In principle, I feel it should ultimately be possible to explain
the abstract functions of the mind in terms of processes organised by the
material substance of the brain.

I have declared this position because in Evolution of the Brain, Sir
John Eccles, a distinguished neurophysiologist who won a Nobel prize in
1963 for pioneering work on the nerve-cell mechanisms in the spinal cord,
espouses the opposite view. He believes that mental processes, such as perception,
thoughts, feelings, memories and imaginings have no physical basis but that
they in some way interact with the physical mechanisms of the brain to produce
behaviour. This ‘dualist-interactionist’ position leads Eccles to the analogy
that the self in each of us is a programmer steering our personal computer
through life. He sees this self as the soul, planted by a divine agency;
a consequence of his stance is that there must be some sort of purpose in
biological evolution.

Unfortunately, nothing in this book persuades me that the dualist-interactionist
standpoint is either necessary or useful. In the opening chapters we are
given a selection of information about the systems that distinguish humans
from apes but there is little attempt at synthesis, so I fear this material
will be hard going for those without a background in neurophysiology. This
survey does not review the various current hypotheses about human evolution,
nor is a new hypothesis developed. The arguments in the following chapters,
dealing with the evolution of the mind, the self and the human person, are
muddled and often contradictory and the literature cited in their support
is both selective and dated.

That Eccles believes in the supernatural nature of the mind emerges
only gradually in the second half of the book. Central to his argument is
a mechanism he proposes for the interaction between the non-physical mind
and the physical brain. This is based on an analogy between mental events
and probability fields in quantum physics. He suggests that mental events
influence the probability of nerve cells communicating with each other by
increasing the release of synaptic vesicles, which contain the molecules
used to carry information from one nerve cell to another. The analogy is
flawed, for probability fields have no influence but simply describe what
may happen. From a physiological point of view it is in any case difficult
to see how much a mechanism could have the necessary selectivity to ensure,
for example, that thoughts of food result in eating and not in playing tennis.

There is a danger that all books written by Nobel prizewinners will
be considered authoritative. Eccles points out how easy it is to stray outside
the scientific terms of reference when dealing with the mind-brain problem,
but I am afraid he has done just this with his mental-event-field hypothesis.
He is confusing beliefs with science.

The mind-brain problem is fascinating and neuroscientists could well
devote more thought to it. Although it is unresolvable in our present state
of ignorance, the unitary, or so-called materialist, approach should at
least produce testable hypotheses. Eccles considers this approach demeaning.
I see no reason why it should be: the search for mechanisms reinforces rather
than detracts from my sense of awe and wonder that natural processes could
have produced abilities as amazing as those of the human mind.

Jennifer Altman is a research consultant and freelance writer who specialises
in the neurosciences.