Guide

The arithmetic operations always depend on the integrity of two simultaneous synthesis of cerebral schemes of operation analyzed by Luria, well-known Russian neuro-psychologist.

If we mentally subtract 8 from 41, we used to subtract 8 from 40 and afterwards we add the unity remained.

The things became more complecated if two numbers with which we work consist of two figures.

These operations generally result impossible for patient with a lesion of the left parieto-occipitale zone.

Nevertheless if the lesion is located the deficit can be notice only in case of complex operations but, in case of massive lesions, patients are also unable to operate elementary arithmetic.

Acalculia is known for a long time in encephalopathic patients and the searches have underlined that the Brodmann’s 39 and 40 areas are the most involved in these functions.

Moreover I would like to remember that there are examples of exceptional mathematical ability clearly accompanied by mental deficit and cases of subjects with linguistic and spatial intelligence above average having evidented acalculia also in absence of lesions.
These examples tell that unnormal development of a mental function can sometimes happen against others.