A NEURAL BASIS FOR THE RETRIEVAL OF CONCEPTUAL KNOWLEDGE

Both clinical reports and systematic neuropsychological studies have s hown that patients with damage to selected brain sites develop defects in the retrieval of conceptual knowledge for various concrete entitie s, leading to the hypothesis that the retrieval of knowledge for entit ies from different conceptual categories depends on partially segregat ed large-scale neural systems. To test this hypothesis, 116 subjects w ith focal, unilateral lesions to various sectors of the telencephalon, and 55 matched controls, were studied with a procedure which required the visual recognition of entities from three categories-unique perso ns, non-unique animals and non-unique tools. Defective recognition of persons was associated with maximal lesion overlap in right temporal p olar region; defective recognition of animals was associated with maxi mal lesion overlap in right mesial occipital/ventral temporal region a nd also in left mesial occipital region; and defective recognition of tools was associated with maximal lesion overlap in the occipital-temp oral-parietal junction of the left hemisphere. The findings support th e hypothesis that the normal retrieval of knowledge for concrete entit ies from different conceptual domains depends on partially segregated neural systems. These sites may operate as catalysts for the retrieval of the multidimensional aspects of knowledge which are necessary and sufficient for the mental representation of a concept of a given entit y. (C) 1997 Elsevier Science Ltd.