Abstract
Classification of word-finding difficulty is based on different stages of naming, which are related to distinct anatomical areas. Recent studies using Positron Emission Tomography (PET) revealed that word knowledge was organized categorically in the left hemisphere. We studied 42 patients with focal brain lesions, 5 patients with Alzheimer's disease, and 25 normal controls on a picture-naming task consisting of 100 nouns in 10 different categories, a category-naming task and a verbal fluency test in 10 categories. Intergroup comparison revealed that aphasics showed significantly poor performance in each task except naming body parts and vegetables, recalling people's names and names of something round. In comparison between patients with and without left frontal lobe lesions, we found that the former had significantly lower scores than the latter in the verbal fluency test, but not in the category- or picture-naming tasks. Patients with Alzheimer's disease showed disturbances in the category-naming and verbal fluency tests, but not in the picture-naming task. The longitudinal study of a patient with semantic aphasia revealed that naming and pointing to body parts was relatively preserved compared with other categories. The task applied and category of words are crucial factors to elucidate the nature of word-finding difficulty.
