There are many myths about our brains--and as many amazing facts, as revealed in a fascinating new book by Sandra Aamodt and Sam Wang, two leading neuroscientists. Here, they explain some of the most surprising secrets of our grey matter...

FACT: You can't tickle yourself
When a doctor examines a ticklish patient, they place one of the patient's hands over their own to prevent the tickling sensation.

Why does this work? Because no matter how ticklish you are, you can't tickle yourself.

This is because your brain focuses on what's going on in the outside world--to prevent important signals from being drowned out in the endless buzz of sensations caused by your own actions.

For instance, this means you're unlikely to notice the texture of your socks, but you would feel a tap on the shoulder.

The patient doesn't feel the tickling because his brain thinks it's his own hand doing the action.

FACT: Looking at a photograph is harder than playing chess
When computer scientists first began trying to write programs to mimic human abilities, they found it relatively easy to get computers to follow logic and do complex maths--such as those required in chess moves--but very hard to get them to figure out what they were seeing in a visual image.

Today's best computer programs can beat a grand master, but any toddler can beat the top programs when it comes to making sense of the visual world.

One reason for this is the difficulty in identifying individual objects.

You only see this ambiguity when you see something briefly enough to misidentify it--like when that rock in the middle of the dark road suddenly turns out to be the neighbor's cat.

MYTH: You only ever use about 10 percent of your brain
Although half the world's population thinks this, in reality, you use your whole brain everyday. But for the myth to stick around for so long, it must have been saying something that we really want to hear. In fact, its impressive persistence may depend on its optimistic message: "If we only use 10 percent of our brains, think what we could do if we could use even a tiny bit of that other 90 percent."

The truth is, studies of brain activity show that even simple tasks actually produce activity throughout the entire brain.

FACT: Yawns wake up the brain
We may associate yawning with sleepiness and boredom, but in actual fact, it wakes us up.

The action itself expands our windpipe, allowing air into the lungs and oxygen into the blood, making us more alert.

Think of yawns as your body's attempt to reach full alertness in situations that require it.

They are contagious. No one is sure why, though it might be advantageous to allow individuals quickly to transmit to one another a need for increased wakefulness.

Yawns are not contagious in other mammals, but the ability to recognize a yawn may be fairly general.

For example, dogs yawn in response to stressful situations and are thought to use yawning to calm others.

MYTH: Blind people hear better
When tested, blind people are not better at detecting faint sounds.

But blind people do have better memories. Since they cannot rely on vision to tell them things, they have to use them constantly--helping sharpen their spatial memory (responsible for recording information about the environment).

They also do better at language tasks, including understanding the meaning of sentences, and at pin- pointing the source of sounds, which may be another way of keeping track of where things are.

The seem to improve these abilities by taking advantage of brain space that isn't being used for vision.

FACT: Computer games help you multi-task
The modern world is full of non-stop action--instant messaging, e-mail, video games, and it all seems to be happening at once.

If you're over 30, you've probably wondered why younger people aren't overwhelmed by all this stimulation. But their brains are simply trained to handle it.

Sustained practice at multi-tasking increases one's ability to pay attention to many things at the same time.

A major source of practice is playing action video games--you know, the kind most parents hate, where the aim is to shoot as many enemies as possible before they shoot you.

These games require players to distribute attention across the screen to quickly detect and react to events.

In one study, college students who played action video games regularly processed information more quickly, could track more objects at once, and had better task-switching abilities.

So, allowing your children to play computer games may not be such a bad thing after all.

MYTH: A bigger brain makes you more intelligent
The size of your brain does not reflect your intelligence--after all, Einstein's brain was no larger than the average person's.

However, research suggests that your intelligence may depend on when the synapses--the gaps between the brain cells--form.

Synapses grow and shrink during childhood and adolescence, and the patterns in which this happen may affect intelligence.

FACT: Exercise helps keep your brain fit
Forget sudoku or crosswords--it's physical exercise that keeps your brain healthy with age.

As your circulatory system ages, the blood supply to the neurons, or brain cells, is reduced, starving them of the oxygen and glucose they need.

Regular exercise increases the number of small blood vessels in the brain (capillaries), in turn boosting the supply of oxygen and glucose to neurons.

In fact, exercise is the single most useful thing you can do to maintain your cognitive abilities later in life; elderly people who have been athletic all their lives do much better mentally than sedentary people of the same age.

To be effective, exercise needs to last more than 30 minutes per session, to occur several times a week, and to elevate your heart rate--but it doesn't need to be strenuous (fast walking works fine).

See you at the gym!

FACT: Your brain uses less power than a fridge light
The messages between your brain cells and the rest of your body are carried by electricity--but only tiny amounts.

The brain uses just 12 watts of power: less than it takes to power the light in the back of your fridge.

Even though the brain is very efficient, it's an energy hog.

It's only 3 percent of the body's weight, yet consumes one-sixth of the body's total energy.

The cost of thinking hard is barely noticeable--most of the brain's energy costs go into maintenance.

MYTH: Listening to Mozart makes babies brainier
There is no scientific evidence for this.

The myth began in 1993 when a scientific journal, Nature, reported that listening to the first ten minutes of a Mozart sonata temporarily improved the performance of college students doing a reasoning test.

The idea was picked up a few years later by an American state governor, who played Beethoven's Ode to Joy to the state parliament and requested $100,000 to send classical music CDs to all parents of newborns in the state.

Of course, the politicians failed to notice that it made no sense to argue that music leads to lifelong intelligence gains in babies based on an effect that lasted under 15 minutes in adults.

The Mozart effect took off from there--despite the fact that no one has tested the idea on babies. Ever. But, by this point, the idea that classical music made babies smarter had been repeated countless times in newspapers, books, and magazines where stories about the Mozart effect have progressively replaced college students with babies.

But while playing classical music isn't likely to improve your child's brain development, something else will--having them play music for you.

Children who learn to play a musical instrument have better spatial reasoning skills--i.e; they think about the physical arrangement of the world in a far more mathematical way (possibly because music and spatial reasoning are processed by similar brain systems).

FACT: Stupid tunes are hard to forget
There's nothing more annoying than the line of a song playing over and over again in your head. Blame it on your brain's ability to recall sequences.

We need to remember sequences everyday, from the movements involved in signing your name or making coffee, to the correct route you need to take to get home from work. The ability to recall these sequences makes everyday life possible.

As you think of a snippet of a song, your brain may automatically associate it with one of these sequences.

This in turn, increases the likelihood that you will recall that snippet, which leads to more reinforcement. It's this cycle which helps with the storing of memories.

How can you break this pattern? One way is to introduce other sequences that interfere with the reinforcement of memory. So, find another infectious song, and hope the cure doesn't become more annoying than the original problem.