The fantastic complexity of how the human mind functions will be laid bare for the first time today when an international team of scientists unveils the world's first "brain atlas".
Neurologists and researchers will be able to access a database via the internet that offers extremely detailed three-dimensional images of the workings of the brain at a microscopic level.
The images have the potential to transform neurosurgery by allowing doctors to plan operations through maps that show how each area of the brain is used for vital tasks from memory to speech.
The giant database, which is being launched at the University of California in Los Angeles, is based on data collected from the analysis of over 7,000 brains by a team across six countries over the past nine years.
Billed as the neurological equivalent of the Genome Project, which three years ago produced the first draft of the 30,000 genes that make up human DNA, the brain atlas is the first attempt to produce a comprehensive picture of the inner workings of a "normal" brain.
While previous attempts to map the brain were based on just one or two specimens, directors of the current project say they have sought to overcome the variability of the brain by taking a huge sample from living and dead subjects.
As a result they have amassed 40,000 gigabytes of information, the equivalent of 40,0000 billion pieces of data, which will become available online at brainmapping.org within the next two years.
John Mazziotta, professor of neurology at UCLA's David Geffen School of Medicine, who has led the $15m (£9.3m) project, said: "No two brains are the same. Their shape. Their size. The way they are organised."
The researchers say the large number of brains they have analysed will eventually produce an overall picture of the average mind and the potential differences in each individual.
They have also produced a clearer picture of the constantly changing networks of billions of neurons or nerve cells that combine from different parts of the brain to produce a specific function.
Professor Mazziotta said: "You can't just point to an area and say, 'here's the seat of language'. The brain handles the challenge of thinking of and initiating a word, and of understanding that word differently. Execution of these tasks involves complex circuitry throughout the brain."
The researchers, in Canada, Finland, France, Germany, Japan and the Netherlands, carried out thousands of scans of people with average blood pressure and pulse to see how they reacted to certain tasks, such as focusing on a chess board or listening to a sound.
The resulting data has been loaded into a supercomputer containing a high-definition "map" of each brain based on age, race, gender and even educational background.
Each anatomical scan can also be overlaid with a picture of where the individual's functions of memory, emotion, comprehension and speech are located. Surgeons say this information will help improve the accuracy of brain surgery.
Dr Neil Martin, head of neurosurgery at UCLA, said: "When we remove a tumour in the brain we have to be sure that we can remove it without damaging the patient's ability to function - to control movement, to read, speak, write and comprehend."
Experts in Britain said the atlas would be a valuable reference, but underlined that much still remains unknown.
Chris Frith, professor of neuropsychology at University College London, said: "We still don't know what the basic units are in the brain - its functioning seems very arbitrary. There is much about it that we simply don't understand."Reuse content