Health: Voyage to the centre of the mind

Breakthroughs in brain scanning reveal more fully how much the mechanics of physiology rule our minds. Such knowledge makes us fear for our souls. Jerome Burne wonders if it should.

Once we laughed at "primitive" tribes who feared photographs would steal their soul. But now it's our own, if not soul, then consciousness or sense of identity, that feels under threat from a technology that can take ever more detailed pictures of our brain working. Remember that secret shudder of disgust you had over a friend's cooking? That could now be spotted on a brain scan.

This week sees the celebration of the 750th anniversary of Bethlehem hospital, now twinned with the Maudsley, a world centre of psychiatric excellence in south London. Among the latest research breakthroughs announced at a press conference yesterday was that, for the first time, pictures had been taken of the precise area of the brain that springs into action when we experience the emotion of disgust.

"This is the first clear evidence that certain emotions are hard-wired," declared Dr Mary Phillips. Not only that but, rather poetically, the location is the same place that responds to taste, the literal meaning of disgust being "bad taste". The idea is that this will ultimately lead to improved treatment for people whose disgust centre is overactive, such as anorexics and patients with obsessive compulsive disorder, who are driven to wash themselves dozens of times a day.

But there is a wider agenda. Dr. Phillips' discovery is a tiny tile in a vast mosaic of brain scan results that have been pouring out from research centres around the world in the last few years. Soon, the hope is, we will have built up a map of glowing points of light in the mysterious grey matter of the brain that show the precise location of such apparent intangibles as thoughts, dreams, feelings and even our sense of self.

The Maudsley is a world-leader in this mapping of interior space and the cartographer -in-chief is Dr Steve Williams, who presides over a piece of hi-tech equipment that he describes as looking like a giant washing machine. It is certainly a claustrophobe's nightmare. You lie down and your head slides through a porthole of chrome and steel into a tube where the magnetism is 10,000 times that of Earth's.

Then, with a glowing bank of instruments that might be controlling a power station, Dr Williams measures blood flow changes in the brain, by recording the radio waves given off by cells vibrating in the powerful magnetic field of the capsule. "We actually measure changes in the molecular structure of water," he explains, "and that tells us where the blood is going. We can pinpoint surges in brain activity in an area as small as 1 square millimetre."

Already the resulting pictures have revolutionised psychiatry. "It wasn't long ago that schizophrenia was thought of as the product of a poor upbringing or even a special form of creativity," says Dr Edward Bullmore, who studies schizophrenia at the Maudsley. "But our scans show their brains are wired up in a different way to normal people. They use much more of the right brain to process speech, for instance." Brain scanning is also pointing the way to understanding what goes on when patients are hearing voices.

"There is a bit of the brain that is active when we are talking to ourselves," says Bullmore, "and another bit that gets turned on when we listen to other people talking to us.

"In normal brains the `listening to other people' bit gets turned off when we are talking to ourselves, but in schizophrenics it doesn't." Such findings may lead to greater understanding of how normal speech works, as well as pointing the way to drugs that can turn off rogue areas.

One of the most controversial projects of these neurologic topographers is discovering differences between male and female brains. Again the Maudsley has come up with a first. It now seems that the brains of men and women age differently. "We know that women are more likely to get Alzheimer's but it's never been clear why," says Dr Declan Murphy. "Now a scanning project has found that the neurons in women's brains are more likely to die off in two particular areas as they get older."

The decline happens in the hippocampus, which deals with memory, and the parietal, which we use for finding our way around. Men, on the other hand, are more likely to lose cells from the frontal lobes, which are involved in speech, judgment and planning. This fits in with Alzheimer's because the disease tends to attack precisely those areas that are already on the wane in women's brains anyway.

Although the British pioneers on this frontier are typically cautious at this early stage, in the States some pundits are already sounding the alarm at the implications of the marriage between brain scans, and modern genetics. For instance, at the end of last year Forbes magazine carried a jeremiad from cultural trends guru Tom Wolfe - complete with copious quotes from Nietzsche - warning of the imminent collapse of the West as the new neurosciences undermined our notions of free will and personal responsibility.

The high-priests of the neurosciences, he says, have rushed into the vacuum left by the death of rival explanations of how our lives are shaped. After the toppling of Freud (blame the parents) and Marx, (blame society) what we are left with is the blueprint of our genes, expressed in the language of brain cells. Hardly a week goes by without some new link being forged between genes and behaviour. Intelligence, a propensity for addiction, violence, a desire for novelty - all have been attributed to genes.

"The notion of a self who postpones gratification, curbs sexual appetite, has vanished," thunders Wolfe. "Since consciousness and thoughts are entirely the physical products of your brain (which) arrives fully imprinted at birth, what makes you think you have free will? The ghostly self does not exist; brain imaging proves it."

Inevitably such metaphysical speculations don't receive much attention at the sharp end of research, so engrossing is the sheer weight of technical problems and the excitement of discovery. So when I asked Dr Williams and Dr Phillips for their vision of psychiatry in the year 2020 they suggested nothing to allay Wolfe's fears. Dr Phillips expected to be able to scan a brain and pick out any problem areas - difficulty in controlling anger, tendency to anxiety - just from the pictures, while Dr. Williams saw international databases holding maps of what a normal brain should look like so abnormalities could be easily spotted.

However their morality circuits seemed intact as well. Both agreed that while in theory it would be quite possible to use brain scanning as a form of lie detection - the fear and anxiety centres in the amygdala should show extra activity during lying - neither felt this was an appropriate use.

But maybe the threat to notions of responsibility and a moral self is due to a misunderstanding, not only of what scanning can do, but how genetics work. Far from being hard-wired at birth, the latest findings about how our brains develop suggest that environmental influence is crucial. As Terrence Deacon points out in The Symbolic Species, his new and controversial book on the development of language, there is just not enough room on our chromosomes to code for even a fraction of the 100 billion neuron connections that develop by the age of two. How the brain is wired up is crucially affected by external factors like nutrition, stimulation and even love. The smart way to talk about the role of genes is not as determining anything, but in terms of how they interact with the environment.

Studies with identical twins have revealed this process at work. "If one half of a twin pair has schizophrenia" says Bullmore "there is only a 50 per cent chance that the other, with exactly the same genes, will get it. Equally, when we scan the brains of normal relatives of schizophrenics we find signs of the abnormalities that show up in patients' brains, but they don't seem to be affected by them."

Fears that scanning will reduce the brain to a predictable system of switches and circuits look like proving groundless. "The latest theory about higher mental processes like `will' or `self' is that they are the product of a network, several brain areas working together," explains Bullmore. "But their huge complexity means that they are probably inherently unpredictable. Mathematically speaking, they are chaotic systems that we may be able to understand better but never describe completely."

Originally brain scanning looks like the ultimate materialist's tool - thoughts are no more than the action of brains cells and we can watch them being generated. But new findings show it's a two-way process. After therapy, obsessive compulsive patients are better and their brains cells have changed, sculpted by nothing more substantial than a new idea. Maybe the self will retain its power, and responsibility, too.

Today the exhibition "Bedlam: Custody, Care and Cure" opens at the Museum of London. It contains paintings from past and present patients, such as Richard Dadd, as well as historical photographs and an interactive CD-ROM describing the latest advances in psychiatry.