fMRI responses to words repeated in a congruous semantic context are abnormal in mild Alzheimer's disease

NEUROPSYCHOLOGIA

卷:48

Article

Olichney, John M.¹  Taylor, Jason R.²  Chan, Shiaohui³  Stringfellow, Andrew⁴  Hillert, Dieter G.⁵  Simmons, Amanda L.⁶  Salmon, David P.⁵  Iragui-Madoz, Vicente⁵  Kutas, Marta⁷ 

[1] Univ Calif Davis, Davis Sch Med, Ctr Mind & Brain, Dept Neurol, Davis, CA 95618 USA

[2] MRC, Cognit & Brain Sci Unit, Cambridge, England

[3] Natl Taiwan Normal Univ, Dept English, Taipei, Taiwan

[4] Univ Calif San Diego, San Diego, CA 92103 USA

[5] Univ Calif San Diego, Dept Neurosci, San Diego, CA 92103 USA

[6] Calif State Univ Sacramento, Dept Psychol, Sacramento, CA 95819 USA

[7] Univ Calif San Diego, Dept Cognit Sci, San Diego, CA 92103 USA

关键词: Memory;    Semantic;    Language;    Medial temporal lobe;    Cingulate;   

DOI  :  10.1016/j.neuropsychologia.2010.04.021

来源: Elsevier

【 摘 要 】

Background: We adapted an event-related brain potential word repetition paradigm, sensitive to early Alzheimer's disease (AD), for functional MRI (fMRI). We hypothesized that AD would be associated with reduced differential response to New/Old congruous words. Methods: Fifteen mild AD patients (mean age = 72.9) and 15 normal elderly underwent 1.5T fMRI during a semantic category decision task. Results: We found robust between-groups differences in BOLD response to congruous words. In controls, the New > Old contrast demonstrated larger responses in much of the left-hemisphere (including putative P600 generators: parahippocampal, cingulate, fusiform, perirhinal, middle temporal (MTG) and inferior frontal gyri (IFG)); the Old > New contrast showed modest activation, mainly in right parietal and prefrontal cortex. By contrast, there were relatively few regions of significant New > Old responses in AD patients, mainly in the right-hemisphere, and their Old > New contrast did not demonstrate a right-hemisphere predominance. Across subjects, the spatial extent of New > Old responses in left medial temporal lobe (MTL) correlated with subsequent recall and recognition (r's >= 0.60). In controls, the magnitude of New-Old response in left MTL, fusiform, IFG, MTG, superior temporal and cingulate gyrus correlated with subsequent cued recall and/or recognition (0.51 <= r's <= 0.78). Conclusions: A distributed network of mostly left-hemisphere structures, which are putative P600 generators, appears important for successful verbal encoding (with New > Old responses to congruous words in normal elderly). This network appears dysfunctional in mild AD patients, as reflected in decreased word repetition effects particularly in left association cortex, paralimbic and MTL structures. (C) 2010 Elsevier Ltd. All rights reserved.

【 授权许可】

Free