How far can we train mental calculation? Mental calculators are people with a prodigious ability in some area of mental calculation, such as multiplying large numbers or factoring large numbers.


Unfortunately I forgot where I heard it, but I remember that it was said that they use parts of the brain that are responsible of motion. So factoring for them is like hitting the light switch or walking.

Assuming that this is correct, isn't it possible to train this ability by performing arithmetics while walking?

From a computer scientist's view, I think this is comparable to the use of the graphic card's CPU to speed up computation. Mental calculators just have the right software to run their GPU. Or do they have a different hardware, and is there no way for the rest of us to achieve this?
Yes the brain is plastic and expands certain areas while shrinking other areas. The more intense the training regiment the more likely it is to destroy the person's normality. Essentially increasing the power, overclocking and short circuiting the brain are possible through mental illness or the correction of mental illnesses. In America many professionals and college students go to psychiatrist to improve their performance. Commonly prescribed performance enhancing drugs are SSRI's which induce hypomania, ADHD drugs which increase dopamine as well as anti-anxiety drugs like the benzodiazepines.

OCD with the ritual of mathematics will cause further specialization at the cost of ability to control responses to anxiety. Psychosis can cause people to be extremely focused on a single topic and their brain the work abnormally fast at the cost of their attachment to reality (It also can diminish intelligence over time). Hypergraphia will allow them to communicate the inspirations of psychosis in great detail. Finally Mania will endow the person with the ability to sleep a minimal amount and give an abundance of energy at the expense of impulse management. 

Examples of mental illness induced greatness are very numerous. Many advances in science and art happen because most geniuses in addition to having an high IQ are also mentally ill. Extreme creativity and productivity are linked to mental illness. Such greats include Einstein, Darwin, John Forbes Nash, Jr. Michelangelo and Vincent van Gogh. Many great works of literature especially religious writings are caused by compulsions to share ie Hypergraphia. OCD can lead to perfectionism and questioning of validity of that which is known. Hypomania allows a person to be more productive than when they have full blown mania. Inducing hypomania (with caffeine and the like) is extremely common in academia as a means of studying or "cramming". Students often go long periods of time with very little sleep and high energy qualify for manic disorder. Psychosis can be slow onset beginning with isolated episodes and developing into a major psychotic break. A sick person may cope with extreme levels of dopamine in their system without anti-psychotics. It is common to be psychotic (having special revelations, hallucinations, hearing voices and bizarre in behaviour) and be a religious important person. Not all spiritual/religious people are psychotic of course.