Of all our organs, the brain distinguishes us a human beings. Our limbs, eyes, ears, lungs – all other parts on our system -are not remarkable when compared with those of animals. Most birds have far better eyesight; many wild beasts can outrun us. But no other creatures have our ability to reason, to judge, to create, to make and appreciate music and poetry.
As Hippocrates, the Greek father of medicine, once observed, ‘From the brain and the brain only arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs and fears.’ The brain is indeed the master organ, controlling all other organs and systems in our bodies.
Many people have likened the brain to a computer. A computer processes information one step at a time, after it has been programmed, or instructed, to do so. No computer can reject its program – decide, indeed, that it doesn’t want to work. Computers cannot laugh and no computer has ever fallen in love.
If, by some strange chance, we had never seen a computer and had found one on the Moon, we would soon have unravelled its mysteries, awesome as they might seem. Nothing yet found in the Universe compares with the complexity of the human brain, which remains the last great biological frontier.
Every second of our lives the brains sends and receives some fifty million messages. It controls our thoughts and emotions, stores our memories and directs every voluntary and involuntary move we make. Without our brains we could not breathe, process our food, get rid of wastes.
How, precisely, it works – what in the braid does what – we are only now beginning to discover. In the remaining years of what former US President George Bush declared the ‘Decade of the Brain’, neuroscientists hope to plot with the precision of the finest mapmakers the millions of micro-contours of this uncharted world. The voyage of discovery is enormously challenging. Inside the brain are some 100,000 million cells, or neurons. From each one comes a baffling maze of perhaps another 100,000 fibers. The map-makers’ job is to identify how – when we retrieve a fact from our memory store, for example – which pieces in the puzzle come into play.
The cartographers are not by any means starting from scratch. Already, scientists have found many ways to explore some of the brain’s geography. In the past, they examined the brains of dead people who had been paralyzed by a stroke or had suffered some neurological problem. In doing so, specialists often found a tumour or other abnormality.
In recent years, they have looked at patients with various brain lesions, or scars, and noted how they lacked certain abilities,. Similarly, surgeons have given electrical stimulation to conscious patients during brain surgery. By such means, we have gradually pinpointed areas of the brain that seem to control specific functions.
Scanning devices such as CAT, for computerised-axial tomography, have already given us superb pictures of a healthy brain’s structure. Into play now come several other technologies designed to track the electrical, magnetic and chemical power by which the brain conveys its messages.
By means of PET, positron emission tomography, researchers can discover which brain cell work in certain tasks. Active cells consume more glucose, the body’s fuel. Volunteers are injected with radioactive glucose, then tested in various ways. A PET scanner tracks the passage of glucose to see which brain cells are demanding fuel. The scanner reports areas of heightened activity to a computer, which produces maps of the neural hot spots. Similar scanners peering into to the skull can track the brain’s blood flow and record its multitude of magnetic and electrical impulses.
When the map making is complete we will have opened windows into the mysterious contours of the brain. That itself will be a remarkable achievement, but nothing compared with the awesome nature of the brain itself which, after all, is masterminding its own exploration.