Introduction. The investigation of lexical semantic representation in Alzheimer's disease.

The study of lexical semantic representation is central to an understanding of brain and language. In Alzheimer's disease, neuropathological alterations consistently involve neocortical areas in which lexical semantic information is represented, and patients with this common dementing disorder evince priminent lexical semantic disturbances. General issues concern the establishment of new semantic memories, the manner in which meaning is represented within the lexicon, the retrieval of semantic information from the lexicon, and the relation between lexical semantics and nonlinguistic cognitive processes. Studies of lexical semantic representation in patients with Alzheimer's disease are especially informative in considering all but the first of these key issues.