The understanding of quantifiers in semantic dementia: a single-case study.

This study investigates the processing of quantifiers in a patient (AM) with semantic dementia. Quantifiers are verbal expressions such as "many" or "a few", which refer semantically to quantity concepts although lexically they are like non-quantity words. Patient AM presented with preserved understanding of quantifier words and impaired understanding of non-quantifier words of the same frequency. In parallel to this, he showed preserved numerical knowledge and impaired comprehension of the meaning of words, objects, and of linguistic concepts. These results suggest that the neural organization of quantifiers is within the numerical domain as they pattern with numerical concepts rather than linguistic concepts. These data reinforce the evidence that numerical knowledge is functionally distinct from non-numerical knowledge in the semantic system and indicate that the semantic referent rather than the stimulus format is more relevant for semantic processing.