Poster E56, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Left Anterior-Posterior Aging effect for lexical production. Functional MRI assessment.
Elena Hoyau1,2, Emilie Cousin1,2,3, Cédric Pichat1,2, Assia Jaillard3, Monica Baciu1,2; 1Univ. Grenoble Alpes, LPNC, F-38040 Grenoble, France, 2CNRS, LPNC UMR 5105, F-38040 Grenoble, France, 3UMS IRMaGe, IRM 3T, CHU Grenoble, Univ. Grenoble Alpes, F-38043 Grenoble, France
Older adults report problems with finding words, suggesting difficulties with word retrieval and generation. However, experimental evaluation of lexical production does not indicate significant decrease in performance, suggesting compensatory strategies. Among explanations for naming difficulties, the access to semantic memory and lexical representations has been emphasized. Moreover, several models of functional reorganization were described (e.g., Hemispheric Asymmetry Reduction in Older Adult; Posterior-Anterior Shift in Aging). Our fMRI study evaluates the (a) inter- and (b) intra-hemispheric reorganization of cerebral networks underlying the lexical production during a Picture Naming (PN) task. Two groups of participants, Young (Y; < 56 years old, n=15) and Old (O; > 56 years old, n=14) were examined. They also underwent neuropsychological assessment for language and memory. PN reorganization was assessed within regions commonly activated during naming. The %CR for PN showed no difference between Y and O. Our fMRI results supporting compensatory mechanisms showed increased left anterior-posterior asymmetry for PN, with O being more posterior than Y. Two groups of O were observed, one with high posterior asymmetry (High Group, HG), one with low posterior asymmetry (Low Group, LG). Compared to HG, the LG showed (i) higher left inferior frontal gyrus (IFG) activation and (ii) lower verbal fluency scores. We suggest that the supplementary recruitment of the left IFG is related to increased neural resources for executive functioning to compensate for a decline of word-retrieval mechanism. We defend a new form of modulation of functional reorganization of language production, the left anterior-posterior aging (LAPA) effect.
Topic Area: LANGUAGE: Development & aging