title: Patterns of regional brain hypometabolism associated with knowledge of semantic features and categories in Alzheimer's disease.
abstract: The study of semantic memory in patients with Alzheimer's disease (AD) has raised important questions about the representation of conceptual knowledge in the human brain. It is still unknown whether semantic memory impairments are caused by localized damage to specialized regions or by diffuse damage to distributed representations within nonspecialized brain areas. To our knowledge, there have been no direct correlations of neuroimaging of in vivo brain function in AD with performance on tasks differentially addressing visual and functional knowledge of living and nonliving concepts. We used a semantic verification task and resting 18-fluorodeoxyglucose positron emission tomography in a group of mild to moderate AD patients to investigate this issue. The four task conditions required semantic knowledge of (1) visual, (2) functional properties of living objects, and (3) visual or (4) functional properties of nonliving objects. Visual property verification of living objects was significantly correlated with left posterior fusiform gyrus metabolism (Brodmann's area [BA] 37/19). Effects of visual and functional property verification for non-living objects largely overlapped in the left anterior temporal (BA 38/20) and bilateral premotor areas (BA 6), with the visual condition extending more into left lateral precentral areas. There were no associations with functional property verification for living concepts. Our results provide strong support for anatomically separable representations of living and nonliving concepts, as well as visual feature knowledge of living objects, and against distributed accounts of semantic memory that view visual and functional features of living and nonliving objects as distributed across a common set of brain areas.
authors.affiliation: Albert-Ludwigs-University Freiburg. zahnr@ninds.nih.gov
authors.forename: Roland
authors.initials: R
authors.lastname: Zahn
authors.forename: Peter
authors.initials: P
authors.lastname: Garrard
authors.forename: Jochen
authors.initials: J
authors.lastname: Talazko
authors.forename: Matthias
authors.initials: M
authors.lastname: Gondan
authors.forename: Philine
authors.initials: P
authors.lastname: Bubrowski
authors.forename: Freimut
authors.initials: F
authors.lastname: Juengling
authors.forename: Helen
authors.initials: H
authors.lastname: Slawik
authors.forename: Petra
authors.initials: P
authors.lastname: Dykierek
authors.forename: Bernd
authors.initials: B
authors.lastname: Koester
authors.forename: Michael
authors.initials: M
authors.lastname: Hull
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D001921:Brain / Q000000981:diagnostic imaging; D001923:Brain Chemistry / Q000502:physiology*; D001931:Brain Mapping; D003627:Data Interpretation, Statistical; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D019359:Knowledge; D008297:Male; D008568:Memory / Q000502:physiology; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D011578:Psycholinguistics; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012660:Semantics
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18