We use 100% of our brain.
The idea that we only use a small percentage of our brain is a myth.
One reason this myth has endured is that it has been adopted by psychics and other paranormal pushers to explain psychic powers.
The popular media and some very influential thinkers have contributed to this misconception. Statements that humans only use a small portion of their brains have been attributed to physicist Albert Einstein and anthropologist Margaret Mead. And the advertising industry is guilty of using the idea to sell their products.
Regardless of its origin, experts in the field of neurology seem quite certain that although certain pathways in the brain may be working at different activity levels, all parts of the brain are always being used—even during sleep.
Here is a link to a page called Do We Only Use 10% of our Brain? which has more information about the topic and additional links to further research.
The truth is that many people suffer from an under excersiced brain. It is a growing problem in our afluent western society. Many people are often mentally tired after spending a day at work and then having to deal with the family chores, but this kind of mental excersise is routine and repetitive, and does nothing to grow, repair or excersise the brain.
Mental brain neurologists have recently been explaining ways to enlarge and expand, neural connections therefore enabling more complex thought and adaptive coping to complex problems.
The most common problems are :-
1) People not getting enough physical excersise.
2) Not getting enough sleep
3) Not eating well enough
4) Watching television everyday
This has a dramatic effect on the brain's función, because a healthy blood supply has a direct effect on the communication between varius parts. A poor blood supply will lead to parts of the brain being slow, possibly forgetfulness, inability to realise obvious things, and in severe cases localised brain death, memory loss, alzheimers and paralysis.
When an adequate regular excersise routine is in place then, there are several things which can be done to build new pathways and vessels within the brain structure. These often include finding new ways to do basic tasks.
1) Eat breakfast with chopsticks.
2) Spend an hour every week to learn a foreign language
3) Tie your shoelaces with one hand
4) Brush your teeth with your other hand
5) Read a book upside down
7) Stand on your head
8) Learn multiplication tables of obscure numbers e.g. 37
9) Play board games with abstract themes like Pictionary
10) Engage in "The Knowlege" excersises, like London taxi drivers, by naming all the roads between two points in your city.
11) Regularly do finger dexterity excersises
12) Listen to classical music esp MOZART
13) Learn to walk around your house with your eyes shut
14) Do puzzles such as Rubiks cube / Jigsaws
15) Learn a computer programming language
16) Learn to play a new musical instrument
17) Write with your other hand
18) Use your computer mouse with your wrong hand
19) Don't smoke
20) Engage in sober intellectual debates
21) Try lots of new hobbies
22) Wear your watch upside down
23) Learn to recite a poem or the alphabet back to front
24) No alcohol earlier than 11am in the morning
26) Don't Eat processed or fast food
Non of these techniques will give you a higher IQ or superbrain, but they will make you cope more easily with life in general, make you less likely to develop some mental conditions, possibly depression, possibly strokes. And will make you a more cheerful, rational, vigorous person and a better and more inventive thinker. In adition you will attain improved sleep and energy levels.