Shabina Akhtar explains: The statement that we use only a small portion of our brain is a myth. To an extent, it has been fuelled by brain imaging techniques which show areas of the brain that are activated during specific tasks. These brain maps, however, show only relative amounts of activity, rather than absolute activity.

“A particular area of the brain may light up during a specific task. But this does not mean that the rest of the brain is non-functional,” says Dr Harsh Jain, consultant neurosurgeon, Apollo Gleneagles, Calcutta.

Neurosurgeons often have to remove substantial portions of the brain in patients with serious head injury, and after recovery these persons may appear normal on cursory examination and conversation. However, careful psychometric testing would reveal significant cognitive deficits in these individuals.

But then how does one measure the percentage of grey matter that is being used? “From an evolutionary perspective, it is unlikely that an organ, large parts of which were “unused”, would be allowed to develop. The brain is an “expensive” organ to maintain and utilises disproportionate amounts of our energy,” says Dr Jain.

It’s true that there is considerable “overlap” of function, but that is to maintain a safety mechanism should certain parts fail. Studies have also shown that if some portions of the brain haven’t been used for a while, they tend to lose their function altogether.

The brain is a very complex organ and it has been possible to unravel its myriad functions only recently. Although there are specific areas known to perform specific functions, they don’t act all by themselves but in unison with other areas, which may be far removed. The assertion that we do not use the whole of our brain at any given point is more a reflection of our lack of understanding of the complexity of the processes involved rather than actual fact.

The question was sent by Smita Bhatia via email