title: Age-related differences in resolving semantic and phonological competition during receptive language tasks.
abstract: Receptive language (e.g., reading) is largely preserved in the aging brain, and semantic processes in particular may continue to develop throughout the lifespan. We investigated the neural underpinnings of phonological and semantic retrieval in older and younger adults during receptive language tasks (rhyme and semantic similarity judgments). In particular, we were interested in the role of competition on language retrieval and varied the similarities between a cue, target, and distractor that were hypothesized to affect the mental process of competition. Behaviorally, all participants responded faster and more accurately during the rhyme task compared to the semantic task. Moreover, older adults demonstrated higher response accuracy than younger adults during the semantic task. Although there were no overall age-related differences in the neuroimaging results, an Age×Task interaction was found in left inferior frontal gyrus (IFG), with older adults producing greater activation than younger adults during the semantic condition. These results suggest that at lower levels of task difficulty, older and younger adults engaged similar neural networks that benefited behavioral performance. As task difficulty increased during the semantic task, older adults relied more heavily on largely left hemisphere language regions, as well as regions involved in perception and internal monitoring. Our results are consistent with the stability of language comprehension across the adult lifespan and illustrate how the preservation of semantic representations with aging may influence performance under conditions of increased task difficulty.
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhuang
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, United States.
authors.forename: Micah A
authors.initials: MA
authors.lastname: Johnson
authors.affiliation: Brain Imaging and Analysis Center, Duke University School of Medicine, United States; Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Madden
authors.affiliation: Department of Linguistics and Cognitive Science, Pomona College, United States.
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Burke
authors.affiliation: Department of Psychology, Pennsylvania State University, United States. Electronic address: mtd143@psu.edu.
authors.forename: Michele T
authors.initials: MT
authors.lastname: Diaz
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D032882:Comprehension / Q000502:physiology; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D010700:Phonetics; D011930:Reaction Time; D012660:Semantics; D055815:Young Adult
keywords: Aging; FMRI; Language comprehension; Lexical competition; Phonology; Semantics