Category-specific anomia: implication of different neural networks in naming.

The occurrence of anomia specifically affecting the ability to name animals is described in three patients. This deficit is contrasted with their capacity to name actions and tools. It is suggested that it is easier to access the names of 'operative' items, which were learned through both visual and sensorimotor experience, than the names of 'figurative' items, which were primarily learned through the visual modality. This hypothesis is consistent with the infero-temporal location of brain damage in these patients. Their ability to retrieve knowledge about operative items is assumed to be due to the sparing of the occipito-parietal area. Because the impairment also involves the recognition of animals, the likely locus of damage is the semantic component of the processing system.