Disturbi di linguaggio e disturbi dell'intelligenza: contributo della neurolinguistica alle teorie sull'organizzazione delle capacità concettuali

We discuss the contribution of neurolinguistics to the study of the relation between linguistic and non-linguisitc cognitive abilities, i.e the set of associative, categorical knowledge usually referred as non-verbal intelligence. To clarify this interaction we first considered the studies on non-verbal impairments in aphasic patients. In a second section the relation between lexical representations and the organisation of the underlying conceptual knowledge are described. This interaction has also been studied on patents with category-specific lexical-semantic impairments and with modality-specific naming disorders (optic aphasia). Altogether, neurolinguistic data seem to contradict the hypotheses that (i) an aphasic impairment is per se a disorder of intelligence, (ii) both disorders are the consequence of a primary asymbolia, (iii) verbal and intellectual impairments associate because of the contiguity of the damaged cortical areas, (iv) an impairment to the classical intelligence scales follows to the damage of non-verbal instrumental abilities. The most plausible explanation of a conceptual impairment in aphasia is the damage to instrumental verbal skills, due to the breakdown of primary lexical competence, or to the impairment of the lexical mediation that are required for the processing of categorical and abstract tasks.