By Rita Carter
A book, written by Rita Carter, a leading science and medical writer, provides extraordinary insights into the way our brains work - and why we behave and act in the ways we do...
ARE WOMEN MORE IN TOUCH WITH EMOTIONS?
There are a number of structural and functional differences between male and female brains.
The human brain is divided into two hemispheres that do different things. They are connected by the corpus callosum, a thick band of nerve tissue that carries information between the two.
This band of nerves is slightly larger, on average, in women than in men - which means the emotional right side of the brain is better connected to the analytical left side.
This may be why women are more emotionally aware. It may also allow emotion to be incorporated more readily into thought and speech.
When doing complex tasks, women use both sides of their brain, while men use the side more obviously suited to the task.
To test your corpus callosum, try the following: Close your eyes and spread out your hands, palms facing upwards. Get someone to touch one of your fingertips (say, on the right hand) and with your opposite hand try to touch the corresponding finger with the thumb of the same hand.
If information is flowing properly between the hemispheres, you should be able to do this without opening your eyes.
Some other questions answered in her book:
INCREDIBLE SHRINKING BRAIN
The adult human brain weighs 31/4lb and has the texture of a firmly set jelly. It contains 100 billion neurons - electrical cells that send signals to one another.
You're born with nearly as many neurons as you'll ever have, but as you mature you make new connections. In childhood, thousands of new connections are made every minute.
The rate at which neurons join up slows with age, but continues through life. Contrary to popular perception, you continue to grow new brain cells in adulthood, but with age, the total number of neurons decreases and the connections degenerate, causing the brain to shrink.
After the age of 20, brain mass decreases by an average 1g a year; by the age of 90, your brain will have lost between 5 and 10 per cent of its volume.
There are also changes in the shape of the brain, with grooves widening - affecting the ability of the neurons to connect - and the forming of tangles and plaques (small discshaped growths).
Alcohol shrinks the brain. However, regular aerobic exercise has been shown to increase brain volume, suggesting it can help to maintain brain health in older people.
WE'RE HALF A SECOND BEHIND THE REAL WORLD
It takes half a second for the unconscious mind to process incoming sensory stimuli, yet we are not aware of this time lag.
When you stub your toe, you get the impression of knowing about it straight away. This illusion of immediacy is created by an ingenious mechanism that backdates conscious perceptions to the time when the stimulus entered the brain - we are tricked into thinking we feel things earlier.
CUTTING CARBS IS BAD
Glucose is the brain's only food and the brain is by far the body's hungriest organ.
Though it accounts for just 2 per cent of the body's weight, it requires 20 per cent of its glucose supplies.
This is obtained from carbohydrate, which is transported to the brain via the bloodstream. It consumes 420 calories a day - around a fifth of your daily calorie intake (or the equivalent of nine Jaffa Cakes).
Because the brain can't store glucose, it must be readily available at all times via the blood supply. Without oxygen or glucose, irreparable brain damage occurs after just ten minutes.
This is why prompt resuscitation is needed in cases of cardiac arrest - to get the blood supplying glucose and oxygen to the brain.
PAIN - IT REALLY IS ALL IN THE MIND
Just how much you respond to pain depends partly on the cingulate area - the inner part of the big valley that runs across the top of the brain from front to back.
People can develop the ability to tone down activity in this region by learning to shift attention away from the pain stimulus, creating a painkilling effect.
Burns victims experience pain relief when using virtual reality glasses to immerse themselves in a cooling environment - this distracts attention away from pain.
WHY HORROR FILMS ARE SCARY
Certain brain cells are activated when you move, and also when you see someone else moving. This means we unconsciously mimic the actions of others and thus share, to some extent, their experience.
These mirror neurons, as they are known, also allow us to know what another person is feeling, without having to think about it.
The discovery of mirror neurons is among the most significant neuroscientific discoveries in recent years.
They mean that when you see someone doing something, in your brain you do it, too - for instance, when you watch a person running, the bit of your brain concerned with planning to move the legs is activated.
And when you see another person expressing an emotion, the areas of your brain associated with feeling that emotion are also activated, making emotions transmittable.
Emotion mirroring is thought to be the basis of empathy. Autistic people often lack empathy and have been found to show less mirror-neuron activity.
Mirror neurons explain why emotion is whipped up in horror film audiences - seeing someone else looking frightened makes you feel scared yourself.
HOW A HEART ATTACK CAUSES ARM PAIN
It seems unconnected to a cardiac attack and yet arm pain is a common sign that the heart is in trouble. This is because it's a form of referred pain.
This occurs when nerve fibres from areas that receive a lot of sensory input, such as the skin, and nerves from low sensory input, such as the internal organs, enter the spinal cord at the same location.
The brain expects to be receiving the data from high sensory areas, so misinterprets the location of the pain.
For instance, in a cardiac attack, pain signals from the heart converge with those from the arm as they enter the spinal cord. The brain interprets them as coming from the arm rather than the heart.
YOU'LL NEVER FORGET EVERYTHING
Our memories are distributed throughout the brain, so even if one part of an experience is lost, many others will remain.
One benefit of such a distributed storage system is that it makes long-term memories more or less indestructible. If they were held in a single area, damage to that place - for example, from a stroke or head injury - would eradicate the memory completely.
As it is, brain trauma and degeneration may nibble away at memories, but rarely destroy them entirely - you may lose a person's name, but not the memory of their face.
Memories are formed by a group of neurons firing together. If the same neurons fire together often, they eventually become permanently sensitised to each other, so that if fires, the others do as well.
When you recall an experience, you recreate it in essence by reactivating the neural patterns that were generated during the original experience that was encoded to memory.
WHY DO SOME PEOPLE NEVER STOP GRIEVING?
Losing a loved one is hard, but most people do recover in time. However, for 10 to 20 per cent of bereaved people, the pain endures and this is referred to as ' complicated grief'.
One study using brain scans found that in such people, reminders of the deceased activate an area of the brain associated with reward, pleasure and addiction, suggesting that prolonged grieving can be a form of addiction.
REAL DR STRANGELOVES
Some people have a hand that is no longer under conscious control. It seems to move on its own, almost as if possessed by another intelligence - just like the character in the 1964 film Dr Strangelove, whose right hand tried to kill him.
Anarchic hand syndrome, as it is known, is due to an abnormality in the areas of the brain that send signals to the muscles.
These areas inhibit many of the signals sent to the body, but in this syndrome they slip through to produce actions beyond conscious control.
WHAT CAUSES CRAVINGS?
As a 'reward' for performing functions essential for the survival of the species, such as eating or reproducing, the brain releases opiates that create sensations of pleasure.
Sugar-rich diets heighten these reward signals, so the more sugar you have, the more you want. This can over-ride self-control mechanisms and lead to addiction.
It's the same with mothers bonding with their babies. Brain scans have shown that when a woman sees a picture of her baby smiling, it triggers strong activity in the brain reward system. Pictures of other babies smiling produced a much weaker response.
HASN'T THIS HAPPENED TO ME BEFORE?
Deja vu is characterised by a sudden intense feeling of familiarity and the sense you have experienced the same moment before.
One explanation is that a situation triggers a memory of a similar experience in the past and wrongly 'tags' it as familiar, creating a sense of recognition without bringing to mind the previous event.
Jamais vu is when you're in a situation that should be familiar, but which seems strange. You may suddenly find your own home to be unfamiliar or for a second not realise that the person approaching you is someone you know well.
This is thought to be a glitch in recognition whereby the emotional input that usually accompanies familiar experiences fails to occur.
IS THAT A FAIRY OR ARE YOU HAVING A BRAIN SEIZURE?
Supernatural sightings vary according to culture. Fairies were once commonly seen, while today people report seeing alien beings. Whatever the nature of the sighting, there may be a far more prosaic explanation.
Claims of being abducted by aliens, for instance, seem to be more common when the magnetic effects of the sun's radiation are high. One theory is that radiation causes tiny seizures in susceptible people, creating hallucinations.
Seeing ghosts may be due to tiny seizures in the temporal lobes - the part of the brain concerned with emotion as well as hearing, language and memory.
Malfunctions in this area could be responsible for the weird effects reported in such sightings, such as feelings of ecstasy or intense fear, and the sense of an invisible presence.
Out-of-body experiences - looking down on yourself - are linked to reduced activity in the parietal lobes, the area of the brain that controls our sense of space and time.
WHAT MAKES PEOPLE RELIGIOUS?
Religious belief and disbelief are driven by parts of the brain to do with emotions, not reasoning.
When a believer thinks about his religion, it activates the part of the brain that processes reward, emotion and taste.
In disbelievers, religion is registered by another part of the brain that generates feelings of rejection. This is the same area that registers disgust when a person is faced with something they can't swallow.
LEARN A LANGUAGE TO STAY YOUNG
Being fluent in two languages, particularly from childhood, enhances cognitive skills and might also protect against the onset of dementia and other age-related cognitive decline.
One reason for this could be that speaking a second language builds more connections between neurons.
Studies show bilingual adults have denser grey matter, especially in the part of the brain where language and communication skills are controlled.
The increased density was most pronounced in people who learned a second language before the age of five.
THE SECRET OF EINSTEIN'S GENIUS
Most brains are the same, but there are small differences. Einstein's brain was found to be wider than normal, and part of a groove that runs through the area involved in maths and spatial reasoning was missing.
It's possible this meant his brain cells could communicate more easily (they didn't have to connect over a gap), giving him his talent for describing the universe mathematically.
Extracted from The Brain Book by Rita Carter
- Daily Mail