Classification learning in Alzheimer's disease

Previous research has demonstrated that explicit recognition of dot pattern s is impaired in amnesic patients with damage to the limbic-diencephalic me mory system, while implicit categorization of the same kind of stimuli is p reserved. The aim of the present study was to investigate the relationship between recognition and categorization performances in patients with Alzhei mer's disease. Consistent with the findings in amnesic subjects, our result s revealed that the explicit recognition of dot patterns was significantly impaired in Alzheimer's disease. However, implicit categorization functions were also disrupted. This was selective for the prototype stimuli; the cat egorization of non-prototype dot patterns was spared. The impaired category learning is likely to reflect the damage of modality-specific neocortical areas in Alzheimer's disease.