DISSOCIATIONS AMONG STRUCTURAL-PERCEPTUAL, LEXICAL-SEMANTIC, AND EVENT-FACT MEMORY-SYSTEMS IN ALZHEIMER, AMNESIC, AND NORMAL SUBJECTS

Patients with Alzheimer's disease (AD), patients with global amnesia ( AMN), and normal control (NC) subjects received tests of recall and re cognition, word-completion priming, and incomplete-picture priming. Th e AD and AMN patients had impaired recall and recognition. The AD pati ents, but not the AMN patients, had impaired word-completion priming. In contrast, the AD patients had intact incomplete-picture priming, a form of priming shown to be perceptual in normal subjects. These resul ts provide neuropsychological evidence for a dissociation between two components of repetition priming, perceptual priming as measured with identification tasks and nonperceptual priming as measured with genera tion tasks. Preserverd perceptual priming in AD may be mediated by the occipital regions that are relatively spared in AD; compromised nonpe rceptual priming may be mediated by temporal regions that show dense n europathological changes early in AD.