title: Impact of changed positive and negative task-related brain activity on word-retrieval in aging.
abstract: Previous functional imaging studies that compared activity patterns in older and younger adults during nonlinguistic tasks found evidence for 2 phenomena: older participants usually show more pronounced task-related positive activity in the brain hemisphere that is not dominant for the task and less pronounced negative task-related activity in temporo-parietal and midline brain regions. The combined effects of these phenomena and the impact on word retrieval, however, have not yet been assessed. We used functional magnetic resonance imaging to explore task-related positive (active task > baseline) and negative activity (baseline > active task) during semantic and phonemic verbal fluency tasks. Increased right frontal positive activity during the semantic task and reduced negative activity in the right hemisphere during both tasks was associated with reduced performance in older subjects. No substantial relationship between changes in positive and negative activity was observed in the older participants, pointing toward 2 partially independent but potentially co-occurring processes. Underlying causes of the observed functional network inefficiency during word retrieval in older adults need to be determined in the future.
authors.affiliation: University of Florida, Department of Clinical and Health Psychology, Gainesville, FL, USA. mmeinzer@ufl.edu
authors.forename: Marcus
authors.initials: M
authors.lastname: Meinzer
authors.forename: Lauren
authors.initials: L
authors.lastname: Seeds
authors.forename: Tobias
authors.initials: T
authors.lastname: Flaisch
authors.forename: Stacy
authors.initials: S
authors.lastname: Harnish
authors.forename: Matt L
authors.initials: ML
authors.lastname: Cohen
authors.forename: Keith
authors.initials: K
authors.lastname: McGregor
authors.forename: Tim
authors.initials: T
authors.lastname: Conway
authors.forename: Michelle
authors.initials: M
authors.lastname: Benjamin
authors.forename: Bruce
authors.initials: B
authors.lastname: Crosson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011930:Reaction Time; D013223:Statistics as Topic; D014706:Verbal Learning / Q000502:physiology; D014825:Vocabulary; D055815:Young Adult
chemical_list: D010100:Oxygen