[Cerebral mechanisms of mathematical thinking]

To suggest a cerebral map of elementary mathematical thinking, and integrate the most relevant findings from neuropsychology with those from cerebral imaging techniques and cognitive behavior experiments.

Firstly we describe investigations into our numerical sense and the way in which numerical information is represented in the human brain. Then, using a multidisciplinary approach, we present the results of different studies of Gerstmann's syndrome, regarding the relation between numerical ability and other cognitive skills; the different participation of the cerebral hemispheres and the special implication of the parietal lobe in mathematical tasks.

Different cerebral regions are involved in doing mental arithmetic, however simple. This makes one think more in terms of cerebral circuits than in a phrenological idea which would assign the responsibility for arithmetical calculations to a specific region. The similarity between the results analysed leads us to the conclusion that one region is particularly involved in understanding numbers, namely the inferior part of the parietal lobe. Different neuronal circuits are used depending on the type of task to be performed. Finally we describe the most relevant models for the processing of numbers which have been developed during the study.