title: Age-related differences in medial temporal lobe involvement during conceptual fluency.
abstract: Not all memory processes are equally affected by aging. A widely accepted hypothesis is that older adults rely more on familiarity-based processing, typically linked with the perirhinal cortex (PRC), in the context of impaired recollection, linked with the hippocampus (HC). However, according to the dedifferentiation hypothesis, healthy aging reduces the specialization of MTL memory subregions so that they may mediate different memory processes than in young adults. Using fMRI, we tested this possibility using a conceptual fluency manipulation known to induce familiarity-related PRC activity. The study yielded two main findings. First, although fluency equivalently affected PRC in both young (18-28; N=14) and older (62-80; N=15) adults, it also uniquely affected HC activity in older adults. Second, the fluency manipulation reduced functional connectivity between HC and PRC in young adults, but it increased it in older adults. Taken together, the results suggest that aging may result in reduced specialization of the HC for recollection, such that the HC may be recruited when fluency increases familiarity-based responding. This article is part of a Special Issue entitled SI: Memory & Aging.
authors.affiliation: Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, United States. Electronic address: ww83@duke.edu.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Wang
authors.affiliation: Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, United States.
authors.forename: Ilana T Z
authors.initials: IT
authors.lastname: Dew
authors.affiliation: Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708, United States.
authors.forename: Roberto
authors.initials: R
authors.lastname: Cabeza
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D003210:Concept Formation / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000098:blood supply; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007600:Judgment; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D021641:Recognition, Psychology / Q000502:physiology*; D012660:Semantics; D013702:Temporal Lobe / Q000098:blood supply / Q000502:physiology*; D014825:Vocabulary; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Aging; Conceptual fluency; Familiarity; Hippocampus; Perirhinal cortex; Priming; Recognition; Recollection