The amazing brain

The news that scientists can switch off our morals with a magnet illustrates how much we still have to learn about our little grey cells, says Richard Gray.

Richard Gray at the University of Essex, wearing a cap with electrodes attached which measure electrical impulses in the brain Photo: Oli Scarff

I once moved an object with the power of my brain. Admittedly, the object in question was a small white bar on a computer screen, and the effort of moving it just a few faltering inches to the left turned me purple with concentration. I also needed to wear a daft-looking skullcap, which had me bristling with wires like a futuristic Medusa. But it is still amazing to recall that, just by thinking at it, I was able to control a computer.
Most of us tend not to contemplate the stuff sitting between our ears. But each of us is carrying around one of the most amazing objects ever created – and one that governs almost everything about how and why we think, feel, act and believe.
For example, we think of our ability to distinguish between right and wrong as a fundamental part of what makes us human, giving us a grasp of morality and philosophy. But yesterday, researchers revealed in Proceedings of the National Academy of Sciences that they had essentially been able to switch off their subjects' moral compasses, by applying powerful magnets to a small region of the brain just behind the right ear.
Volunteers subjected to magnetic pulses to the right temporo-parietal junction, an area that is highly active when we think about the thoughts and beliefs of others, were more likely to make morally dubious decisions. For example, they were asked whether it was right to have let your girlfriend walk across a bridge you knew was unsafe. Because she made it across, the decision was seen as correct; the ends had justified the means.
Such experiments are helping us to realise the extent to which the brain is, in the words of Professor Colin Blakemore, a leading neuroscientist at Oxford University, "the machine that runs our lives". "It is responsible for everything we do," he says, "every belief, intention and action. Physically, all we can do is move our muscles, but to do this we need nerve impulses from the brain. In the same way, moral and ethical choices are just functions of the brain, just as picking up a cup of tea and drinking it is."
In fact, every movement we make and breath we take is determined, subconsciously, by our brains. As a result, it is a greedy organ. The brain makes up just 2 per cent of a person's body weight, but uses around 25 per cent of the oxygen we inhale and consumes 20 per cent of the body's energy. It is the size and immense adaptability of the human brain that is responsible for the transformation of our species from tree-dwelling primates into the dominant species on the planet.
Our brain size was achieved due, scientists now believe, to the demands of social networking (in other apes, it has been observed that the larger the group size, the larger a part of the brain known as the neocortex becomes. It is thought that the human brain grew so large, and our species became so clever, as our social groups expanded).
In its most basic form, the brain is a cluster of nerve cells, capable of communicating with each other using tiny pulses of electricity. Interfere with this communication, as the researchers from MIT did, and strange things start to happen. One often cited example is a rare medical condition known as foreign accent syndrome, of which there have been just 60 recorded cases in the past 70 years. Researchers at Oxford University found that people who have suffered an injury to key parts of their brain underwent a strange transformation. In one case, a stroke victim from Newcastle switched from speaking with a broad Geordie accent to a Jamaican, and occasionally Slovak, tone.
The reason this can happen is that our memories, personalities and behaviour are not innate parts of our genetic make-up but learned information, stored up in those little nerve cells. "The brain is extremely fragile," says Prof Blakemore. "Unlike other parts of our body, like the heart or our muscles, much of the information it holds is not contained within our genes."
If we lose the networks of cells that hold this information, dramatic changes can occur. Using a technique known as Transcranial Magnetic Stimulation, researchers can temporarily switch off parts of the brain. In a paper due to be published later this week in Journal of Cognitive Neuroscience, Dr Joe Devlin of University College London has shown that it is possible to slow volunteers' reading ability by directing magnetic pulses to a part of their brain known as the ventral occipito-temporal cortex.
For an example of this type of brain surgery with a permanent effect, we can look to the case of Phineas Gage, a 19th-century railway worker. Gage was injured in an accident in which a rod passed though his skull and destroyed a large part of his brain. He miraculously survived and was mentally unimpaired, with one exception: his personality. Before the accident, he was hard-working and good-natured, but he became ill-tempered and generally disliked. The rod had damaged a significant part of his frontal lobe, a part of the brain now known to be essential in governing our temperament.
The fact that nerve cells can lose the information they capture is one of their greatest weaknesses – but their response to such accidents showcases one of their greatest strengths. When we have a stroke, our brain is starved of oxygen, causing the catastrophic death of those nerve cells and leaving us paralysed and unable to speak. Yet within days, the same patients start to regain movement and the ability to speak. This is not a sign of nerves coming back to life, but the brain rebuilding itself, creating new nerve connections and bypassing the damaged areas.
"It is extremely useful to have a brain that can remodel and rewire itself," says Professor Blakemore. "The ability of the brain to absorb information, form new memories and learn new skills is all dependent on genetic mechanisms in nerve cells. These enable the cells to change their form, shape, size, connections and therefore their function. They are self-learning devices."
Professor Blakemore believes this property, known as "plasticity", can be exploited to our benefit. Working with researchers in Düsseldorf, he is developing a system that has enabled blind patients to see using sound. He has found that their brains remodel to use variations in pitch, tone and volume – in the same way sighted people use differences in light and colour – to build up a picture of their surroundings. Over several weeks of training, patients became able to recognise different objects using the sounds.
It appears, however, that this process is not just limited to those who have suffered an injury. Dr Heidi Johansen-Berg, from the University of Oxford, recently discovered that practising juggling could lead to changes in the white matter of the brain, enhancing the number of connections between nerves. Her findings have helped to transform conventional ideas about how the brain starts to deteriorate once we reach our teenage years.
"We tend to think of the brain as being static or even beginning to degenerate once we reach adulthood," she says. "We've shown that it is possible for the brain to condition its own wiring system to operate more efficiently." Indeed, scientists are discovering that the brain can be influenced by large numbers of stimuli: computer games such as Tetris have also been found to increase the amount of brain matter.
It is clear, then, that science is only just starting to scratch the surface of what the brain is capable of, and how exactly it makes us who we are. "I suspect that human potential is nowhere near its limits," says Prof Blakemore. "As we accumulate more knowledge, we will change our brains in doing so and so go on to generate yet more knowledge. There might be no limits to what the human brain can achieve."
Parts of the brain
Cerebellum
Co-ordinates movement, balance and reflex reactions. Injury to this part of the brain leads to dizziness and loss of the ability to walk and to control fine movements.
Primary Motor Cortex
Responsible for initiating voluntary movement.
Temporal Lobe
Responsible for hearing, memory formation and recognition of objects. Injuries can lead to short-term memory loss and aggression, and leave victims unable to recognise faces.
Occipital Lobes
These contain the visual cortex, responsible for processing information from the eyes. Recently found to play a major role in reading and writing.
Frontal Lobe
Responsible for consciousness, and governs habits, motor skills and personality traits. Injury can lead to paralysis, mood changes and the inability to plan actions such as making a cup of tea.
Parietal Lobe
Combines sensory information to form a single concept.
Limbic System
The more primal part of the brain, responsible for emotions, sexual arousal, rage and fear. Also controls the biological rhythms of the body.