Español Português
"Understanding the Brain", The Birth of a Learning Science, 2007, page 113
Did We only Use 10% of our Brain? (3)
The Brain Is 100% Active!
The Brain Is 100% Active!
Neuroscience findings now show that the brain is 100% active. In neurosurgery, when it is possible to observe the functions of the brain on patients under local anaesthetic, electric stimulations show no inactive areas, even when no movement, sensation, or emotion is being observed.
No areas of the brain are completely inactive, even during sleep; if they were, it would indicate a serious functional disorder.
Similarly, loss of very much less than 90% of brain tissue leads to serious consequences as no region of the brain can be damaged without causing physical or mental defects.
The cases of people who have lived for years with a bullet lodged in the brain or similar trauma do not indicate “useless areas”. If it is possible to completely recover from such a shock, it is the demonstration of the brain’s extraordinary plasticity: neurons (or networks of neurons) have been able to replace those that were destroyed and in such cases the brain reconfigures itself to overcome the defect.
The myth is implausible for physiological reasons, too. Evolution does not allow waste and the brain, like the other organs but probably more than any other, is moulded by natural selection. It represents only 2% of the total weight of the human body but consumes 20% of available energy. With such high energy cost, evolution would not have allowed the development of an organ of which 90% is useless.
No areas of the brain are completely inactive, even during sleep; if they were, it would indicate a serious functional disorder.
Similarly, loss of very much less than 90% of brain tissue leads to serious consequences as no region of the brain can be damaged without causing physical or mental defects. 
The cases of people who have lived for years with a bullet lodged in the brain or similar trauma do not indicate “useless areas”. If it is possible to completely recover from such a shock, it is the demonstration of the brain’s extraordinary plasticity: neurons (or networks of neurons) have been able to replace those that were destroyed and in such cases the brain reconfigures itself to overcome the defect.
The myth is implausible for physiological reasons, too. Evolution does not allow waste and the brain, like the other organs but probably more than any other, is moulded by natural selection. It represents only 2% of the total weight of the human body but consumes 20% of available energy. With such high energy cost, evolution would not have allowed the development of an organ of which 90% is useless."Understanding the Brain", The Birth of a Learning Science, 2007, page 113
