Secrets of the brain: The grey matter that makes us who we are

From shyness and moral judgement to creativity and sexual preference, a fascinating new book shows how our personalities and human traits are written on our brains. Jeremy Laurance reports

The brain is our most complex but least understood organ. We can name its parts but our knowledge of what each part does, or how, is rudimentary. In The Brain Book, journalist Rita Carter has assembled what is known about the nerve centre of each individual and explains with the aid of images and graphics its structure, function and disorders.



The moral brain

When rail worker Phineas Gage blew a hole in the front of his brain while tampering with explosives in 1848, he provided one of the earliest insights into how the organ worked. The explosion drove a rod through his cheek and out through the top of his head, causing him to lose the sight of his left eye but, remarkably, little other damage. However, his personality changed dramatically and from being a conscientious, polite and thoughtful man, he became rude, reckless and socially irresponsible. Damage to several areas of the brain involved in feeling and thinking can affect moral judgement.



Belief and superstition

A complex interplay of genes, culture and upbringing contribute to people's belief systems, which provide a framework for their experience. But certain aspects may directly reflect brain activity. Some scientists have suggested that supernatural experiences may be the result of disturbances in the brain.

The feelings of ecstasy that accompany them have been attributed to tiny seizures in the temporal lobes. Temporal lobe disturbance has also been associated with the sense of an invisible presence that people who claim to have seen ghosts often report. Out-of-the-body experiences have been linked to reduced activity in the parietal lobes, which normally maintain a stable sense of space and time.

Creativity

There is a striking difference in the brains of musicians who play from a score in front of them and those who improvise. Brain imaging studies have shown that the frontal lobes are activated when musicians are reading the notes but turn off in improvisation, allowing ideas to "float".

Research suggests that this reflects wider creative processes. When the brain relaxes out of sharp attentiveness, shown by tightly-compressed gamma waves on the EEG, into its "idling" mode, marked by slow alpha waves, that is when new ideas tend to occur. Stimuli that might otherwise be ignored are allowed to enter awareness and can resonate with thoughts, memories and existing knowledge.



Sex differences

Brains are as individual to people as faces. But there are broad differences between the sexes, and between differing sexual orientations. The corpus callosum, which links the two sides of the brain, is better developed in women than men. It has been suggested this is why women are more emotionally aware – the right side associated with the emotions is better linked to the left side, the seat of analytical thought.

Brain scans of gay people show structures associated with mood, emotion, anxiety and aggression tend to resemble those in the opposite sex. In gay women, for example, the right side of the brain tends to be larger, a feature shared with heterosexual men. Patterns are similar between gay men and heterosexual women, especially in areas involved with anxiety.



Personality

Studies of the brain have raised the possibility that personality may be "visible" from the activity in different brain areas.

At the crudest level, a person with a "sensitive" brain – one that produces more activity in response to a mild stimulus – are less likely to indulge in sensation-seeking or adrenaline sports than those with "insensitive" brains, who need a lot of stimulation to produce the same level of excitement. Extroverts have reduced activity in response to stimuli in the neural circuit that keeps the brain aroused – involving the prefrontal cortex, anterior cingulate cortex and the thalamus.

People who like novelty have strong links between the hippocampus and the striatum, while shy people show a strong reaction to unfriendly-looking faces in the amygdala. Optimism, co-operation and aggression can be traced to activity-specific brain areas.



Does size matter?

Brains tend to vary little in size, but there are exceptions. Jonathan Swift, the author of Gulliver's Travels, had a brain which weighed an enormous 2,000 grams when he died in 1754, while the brain of Ivan Pavlov, the Russian physiologist who discovered the Pavlovian response, weighed barely 1,500 grams. There is no link between size of brain and intellect but other features may be important.

Einstein's brain, removed after his death, was missing part of a groove that runs through the parietal lobe. The area affected is concerned with mathematics and spatial reasoning and it is thought the missing groove may have allowed neurons in that area to communicate more easily. If so, it could account for his extraordinary talent.



The ageing brain

Most neurons in the brain remain healthy until death. But the brain itself shrinks by 5-10 per cent between the ages of 20 and 90. Other changes include a widening of the grooves and the formation of plaques and tangles – small disc-shaped growths. The significance of these changes is not understood – they may occur in the brains of healthy people and those with Alzheimer's disease.

However myelin decay, affecting the myelin sheath that insulates the neurons, increases with age and can mean brain circuits are less efficient, causing problems with balance and memory. However, decay in the physical brain may be compensated for by the accumulation of knowledge and experience, resulting in improved intellectual performance. Exercise, a healthy diet and engaging in mental tasks such as chess or crossword puzzles can slow mental decline and protect against memory loss.



Headache and migraine

A headache is the commonest reason for taking painkillers – yet the brain has no pain-sensitive nerve receptors. Tension in the meninges – the membranes that surround the brain – or in the blood vessels or muscles of the head and neck may account for some headaches. In others, such as migraines, the pain may be due to a surge of neuronal activity. Migraines usually occur at the front or side of the head and the pain often gets worse with movement. They have a range of triggers – specific foods, tiredness, hormonal changes, emotional factors, or even a change in the weather. A classic migraine attack can last for days and include a postdrome phase during which the sufferer experiences difficulty focusing, poor concentration and increased sensitivity.



Memory

A patient known as HM had brain surgery to control epileptic seizures in 1953, which involved removal of large areas of the hippocampus from both hemispheres of his brain. The operation successfully controlled his epilepsy but had a disastrous side-effect – it destroyed his ability to remember. Like a sufferer from severe Alzheimer's disease, HM was from that day unable to recall, people, places or events. Whenever he met someone, even though he had seen them many times a day, for months or years, he did not recognise them. The case demonstrated the essential role the hippocampus plays in memory storage.



Sleep and dreaming

Without sleep we would die. Sleep is essential for health and if we get too little, the brain becomes confused, and we lose the ability to think and remember. Yet our understanding of what makes sleep so important is still limited.

Sleep-wake cycles are controlled by neurotransmitters that act on areas of the brain. There is also a brain chemical, adenosine, which builds up in the blood during waking hours and begins to cause drowsiness. Once we are asleep it is gradually broken down. Dreaming is most apparent during REM (rapid eye movement) sleep, when the brain is highly active. In deep sleep, brain activity reduces but dreams still occur, often emotionally charged.



Unconsciousness

The conscious brain is responsive to sound, light and pain. But levels of consciousness can descend through confusion, delirium and stupor to coma, under the influence of drink or drugs, injury or infection, and tiredness. Coma results from damage to the parts of the brain involved in maintaining consciousness, especially the limbic system and the brain stem.

There are various degrees of coma, from shallow to deep. In the less severe forms the person may respond to certain stimuli, such as a sudden sound, with a turn of the head or small movements. In persistent vegetative state, the person may appear to sleep and wake and to move their eyes and limbs as if they were awake, but be unresponsive. In deep coma there is no response to stimuli although automatic movements such as blinking and breathing are maintained.



The Brain Book by Rita Carter (Dorling Kindersley, £25). To order this book for the special price of £22.50 with free P&P, go to Independentbooksdirect.co.uk or call 0870 0798897

Suggested Topics
Life and Style
“What is it like being a girl?” was the question on the lips of one inquisitive Reddit user this week
News
peopleDave Legeno, the actor who played werewolf Fenrir Greyback in the Harry Potter films, has died
Arts and Entertainment
Armando Iannucci, the creator of 'The Thick of It' says he has
tvArmando Iannucci to concentrate on US show Veep
Life and Style
beauty
PROMOTED VIDEO
Life and Style
ebookA wonderful selection of salads, starters and mains featuring venison, grouse and other game
Sport
Luis Suarez looks towards the crowd during the 2-1 victory over England
transfers
Life and Style
Swimsuit, £245, by Agent Provocateur
fashion

Diving in at the deep end is no excuse for shirking the style stakes

Sport
German supporters (left) and Argentina fans
world cup 2014Final gives England fans a choice between to old enemies
Arts and Entertainment
A still from the worldwide Dawn of the Planet of the Apes trailer debut
film
News
peopleMario Balotelli poses with 'shotgun' in controversial Instagram pic
News
A mugshot of Ian Watkins released by South Wales Police following his guilty pleas
peopleBandmates open up about abuse
Sport
Basketball superstar LeBron James gets into his stride for the Cleveland Cavaliers
sportNBA superstar announces decision to return to Cleveland Cavaliers
Sport
Javier Mascherano of Argentina tackles Arjen Robben of the Netherlands as he attempts a shot
world cup 2014
Arts and Entertainment
The successful ITV drama Broadchurch starring David Tenant and Olivia Coleman came to an end tonight
tv
Sport
Four ski officials in Slovenia have been suspended following allegations of results rigging
sportFour Slovenian officials suspended after allegations they helped violinist get slalom place
News
14 March 2011: George Clooney testifies before the Senate Foreign Relations Committee during a hearing titled 'Sudan and South Sudan: Independence and Insecurity.' Clooney is co-founder of the Satellite Sentinel Project which uses private satellites to collect evidence of crimes against civilian populations in Sudan
people
Arts and Entertainment
Balaban is indirectly responsible for the existence of Downton Abbey, having first discovered Julian Fellowes' talents as a screenwriter
tvCast members told to lose weight after snacking on set
Life and Style
More than half of young adults have engaged in 'unwanted but consensual sexting with a committed partner,' according to research
tech
Life and Style
A binge is classed as four or more alcoholic drinks for women and five or more for men, consumed over a roughly two-hour period
tech
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    JavaScript Developer (Angular, Web Forms, HTML5, Ext JS,CSS3)

    £40000 - £45000 per annum + Benefits + Bonus: Harrington Starr: JavaScript Dev...

    BC2

    £50000 - £70000 per annum: Harrington Starr: Business Analyst Consultant (Fina...

    SAP Data Migration Consultant

    competitive: Progressive Recruitment: My client, a FTSE 100 organisation are u...

    Programme Support, Coms, Bristol, £300-350p/d

    £300 - £350 per day + competitive: Orgtel: My client, a leading bank, is curre...

    Day In a Page

    A History of the First World War in 100 Moments: Peace without magnanimity - the summit in a railway siding that ended the fighting

    A History of the First World War in 100 Moments

    Peace without magnanimity - the summit in a railway siding that ended the fighting
    Scottish independence: How the Commonwealth Games could swing the vote

    Scottish independence: How the Commonwealth Games could swing the vote

    In the final part of our series, Chris Green arrives in Glasgow - a host city struggling to keep the politics out of its celebration of sport
    Out in the cold: A writer spends a night on the streets and hears the stories of the homeless

    A writer spends a night on the streets

    Rough sleepers - the homeless, the destitute and the drunk - exist in every city. Will Nicoll meets those whose luck has run out
    Striking new stations, high-speed links and (whisper it) better services - the UK's railways are entering a new golden age

    UK's railways are entering a new golden age

    New stations are opening across the country and our railways appear to be entering an era not seen in Britain since the early 1950s
    Conchita Wurst becomes a 'bride' on the Paris catwalk - and proves there is life after Eurovision

    Conchita becomes a 'bride' on Paris catwalk

    Alexander Fury salutes the Eurovision Song Contest winner's latest triumph
    Pétanque World Championship in Marseilles hit by

    Pétanque 'world cup' hit by death threats

    This year's most acrimonious sporting event took place in France, not Brazil. How did pétanque get so passionate?
    Whelks are healthy, versatile and sustainable - so why did we stop eating them in the UK?

    Why did we stop eating whelks?

    Whelks were the Victorian equivalent of the donor kebab and our stocks are abundant. So why do we now export them all to the Far East?
    10 best women's sunglasses

    In the shade: 10 best women's sunglasses

    From luxury bespoke eyewear to fun festival sunnies, we round up the shades to be seen in this summer
    Germany vs Argentina World Cup 2014: Lionel Messi? Javier Mascherano is key for Argentina...

    World Cup final: Messi? Mascherano is key for Argentina...

    No 10 is always centre of attention but Barça team-mate is just as crucial to finalists’ hopes
    Siobhan-Marie O’Connor: Swimmer knows she needs Glasgow joy on road to Rio

    Siobhan-Marie O’Connor: Swimmer needs Glasgow joy on road to Rio

    18-year-old says this month’s Commonwealth Games are a key staging post in her career before time slips away
    The true Gaza back-story that the Israelis aren’t telling this week

    The true Gaza back-story that the Israelis aren’t telling this week

    A future Palestine state will have no borders and be an enclave within Israel, surrounded on all sides by Israeli-held territory, says Robert Fisk
    A History of the First World War in 100 Moments: The German people demand an end to the fighting

    A History of the First World War in 100 Moments

    The German people demand an end to the fighting
    New play by Oscar Wilde's grandson reveals what the Irish wit said at his trials

    New play reveals what Oscar Wilde said at trials

    For a century, what Wilde actually said at his trials was a mystery. But the recent discovery of shorthand notes changed that. Now his grandson Merlin Holland has turned them into a play
    Can scientists save the world's sea life from

    Can scientists save our sea life?

    By the end of the century, the only living things left in our oceans could be plankton and jellyfish. Alex Renton meets the scientists who are trying to turn the tide
    Richard III, Trafalgar Studios, review: Martin Freeman gives highly intelligent performance

    Richard III review

    Martin Freeman’s psychotic monarch is big on mockery but wanting in malice