The assertion that we only use 10 per cent of our brains, and if we were to unlock the other 90 per cent we could attain superior mental powers, is actually a false one.

In fact, most of the brain is active at any one time, and simple functions typically involve several areas of the brain working together at once.

Weighing in at 1.4 kg. and containing about 100 billion nerve cells (neurones), the brain is a seat of constant activity and generates around the same amount of energy as a ten-watt lightbulb. The brain has an unprepossessing, jelly-like appearance, protected by the skull and the meninges (membranes just inside the cranium), and cushioned by a clear liquid called cerebrospinal fluid.

The brain of the modern human is three or four times the size of our earliest ancestor’s but, perhaps surprisingly, has not changed significantly in either size or capacity since the time of the Cro-Magnon people who painted the Lascaux caves 35,000 years ago.

Generally speaking, size does not seem to matter. Einstein’s brain, for example, was of average size and weight (although the part of his brain associated with mathematical reasoning was unusually wide).

Women’s brains are, on average, slightly smaller and lighter than men’s, but this is simply proportionate to the size of their bodies. Debate rages between neuroscientists as to the extent – and implications – of physical differences between men’s and women’s brains.

It is believed by some, for example, that the corpus callosum – the band of nerve fibres connecting the left and right sides of the brain – is thicker in women than in men, and that women tend to use both hemispheres for language tasks. Studies have also suggested that women have more brain cell density in certain areas of the frontal lobe, which controls higher mental processes; that the area of their brain controlling emotional arousal is smaller and functions differently; and – as most women will tell you – that this area responds directly to eating chocolate.

Scientists such as neuropsychiatrist Louann Brizendine, who wrote The Female Brain, use these physical differences to explain why teenage girls feverishly swap text messages, why menopausal women leave their husbands and why - in Brizendine’s words - “the typical male brain reaction to an emotion is to avoid it at all costs”.

Others are dismissive, however, claiming that any distinctions between men’s and women’s behaviour and attitude are more to do with their environment, education and conditioning than their brain structure.

Before birth, the brain of a foetus grows at an astonishing rate, creating 250,000 new neurones every minute. Nevertheless, the brain is still not fully formed at birth (if it were, the baby’s head would be too large to pass through the birth canal). It continues to grow rapidly throughout the first couple of years of life, and certain types of stimulation are essential at this stage: depriving a baby of vision for just a week, for example, can permanently affect his eyesight. By the time a child reaches the age of five, his brain will be more or less the size and weight of an adult’s brain.

Whether we can – and should – enhance our brain’s health and performance is less certain. The last 10 years have witnessed increasing debate over the use of drugs known as cognitive enhancers or intelligence drugs. Some of these are licensed in the UK to treat narcolepsy (a condition involving excessive daytime sleepiness and sleep attacks), but since researchers at Cambridge University showed that they could dramatically improve mental performance in healthy patients, the prospect has arisen of them being used more widely. The Government has asked the Academy of Medical Sciences to undertake an independent review of issues surrounding the use of cognitive enhancers; their report is due to be published in April 2008.

Less controversially, it may be possible to enhance the brain naturally. Some foods are known to be helpful to brain function – a wide range of vitamins, together with proteins, carbohydrates and fats (particularly those containing the fatty acid, omega-3), are believed to assist with fuelling or maintaining particular areas of the brain. The benefits of so-called “superfoods”, however - fashionable goji berries, pomegranates and blueberries and the like – are more open to question. Many nutritional experts believe that simply eating a balanced diet with a range of fruits, vegetables, wholegrains, proteins and fats is a more reliable way to ensure a healthy brain.

It is also thought by most neuroscientists that moderate, aerobic exercise and mental stimulation (“neurobics”), such as performing puzzles and mathematical problems, can help to delay the decline in memory and cognitive skills that comes with age. Put simply, use it or lose it.

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