Priming and semantic memory loss in Alzheimer's disease.
Semantic memory (SM) was investigated in six patients with probable Alzheimer's disease (AD) by on-line measurement of semantic priming in a lexical decision task, and off-line tests of comprehension. Detailed assessment was carried out on naming, name comprehension, and probes of semantic knowledge with a battery of 150 items. The patients performed normally on perceptual tests and displayed an item-specific loss of knowledge on the semantic tests. In a primed lexical decision task, greater semantic priming was found relative to age-matched normals. The priming was substantially greater for items with "degraded" representations as determined by the off-line tests. Lexical decision was also performed more slowly on these items. These unexpected results demand a reevaluation of the concepts of the lexicon and semantic memory structure and their possible alteration in dementia.
Chertkow
H
H
Department of Neurolinguistics, Montreal Neurological Institute, Quebec, Canada.
Bub
D
D
Seidenberg
M
M
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000523:psychology*; D000849:Anomia / Q000523:psychology; D003463:Cues; D004411:Dyslexia, Acquired / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D011939:Mental Recall; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D012660:Semantics; D014706:Verbal Learning