Genetics and mathematics: evidence from Prader-Willi syndrome.

Mathematical abilities were tested in people with Prader-Willi syndrome (PWS), using a series of basic mathematical tasks for which normative data are available. The difference between the deletion and the disomy variants of this condition was explored. While a wide phenotypic variation was found, some basic findings emerge clearly.

Retrieval pathways for common and proper names.

Paradigmatic cases of proper name anomia and proper name selective sparing are reviewed from relevant neuropsychological literature. Available evidence supports the existence of functionally and anatomically distinct retrieval pathways for the categories of proper and common names. An information processing model whose main feature lies in the relative independence within the semantic-conceptual system of information concerning individual entities may account for most of the observed phenomena.

Is math lateralised on the same side as language? Right hemisphere aphasia and mathematical abilities.

The main purpose of the present study was to learn how mathematical abilities are located and develop in the brain with respect to language. Mathematical abilities were assessed in six right-handed patients affected by aphasia following a lesion to their non-dominant hemisphere (crossed aphasia) and in two left-handed aphasics with a right-sided lesion. Acalculia, although in different degrees, was found in all cases.

A deficit for arithmetical procedures: lack of knowledge or lack of monitoring?

A patient is described with a specific deficit for arithmetical procedures. Unlike in previously described cases, where the observed problems could be attributed to the systematic application of disturbed algorithms, this patient's difficulty seems to stem from an inability to monitor the sequence of operations that calculation procedures specify. Criteria are provided for distinguishing impairments in written calculation due to the application of defective knowledge of the procedures from those determined by lack of monitoring.