期刊
NEUROPSYCHOLOGIA
卷 49, 期 9, 页码 2448-2455出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.neuropsychologia.2011.04.022
关键词
Medial temporal lobe; Hippocampus; Learning; Visuo-spatial; APOE epsilon 4; Memory
资金
- Sierra-Pacific Mental Illness Research, Education, and Clinical Center (MIRECC)
- War Related Illness and Injury Study Center (WRIISC)
- Medical Research Service of the Department of Veterans Affairs
- NIA [RO1 AG021632]
- NIH [P30 AG 17824, NIH R37 AG 12713, P41 RR023953, 2P41RR009784]
Apolipoprotein (APOE) epsilon 4-related differences in memory performance have been detected before age 65. The hippocampus and the surrounding medial temporal lobe (MTL) structures are the first site affected by Alzheimer's disease (AD) and the MTL is the seat of episodic memory, including visuo-spatial memory. While reports of APOE epsilon 4-related differences in these brain structures are not consistent in either cross-sectional or longitudinal structural and functional magnetic resonance imaging (fMRI) studies, there is increasing evidence that brain activity at baseline (defined as activity during fixation or rest) may differ in APOE epsilon 4 carriers compared to non-carriers. In this fMRI study, cognitively normal APOE epsilon 4 carriers and non-carriers engaged in a perspective-dependent spatial learning task (Shelton & Gabrieli, 2002) previously shown to activate MTL structures in older participants (Borghesani et al., 2008). A low-level, visually engaging dot-control task was used for comparison, in addition to fixation. APOE epsilon 4 carriers showed less activation than non-carriers in the hippocampus proper during encoding. Specifically, when spatial encoding was contrasted against the dot-control task, encoding-related activation was significantly lower in carriers than non-carriers. By contrast, no epsilon 4-related differences in the hippocampus were found when spatial encoding was compared with fixation. Lower activation, however, was not global since encoding-related activation in early visual cortex (left lingual gyrus) was not different between APOE epsilon 4 carriers and non-carriers. The present data document APOE epsilon 4-related differences in the hippocampus proper during encoding and underscore the role of low-level control contrasts for complex encoding tasks. These results have implications for fMRI studies that investigate the default-mode network (DMN) in middle-aged to older APOE epsilon 4 carriers to help evaluate AD risk in this otherwise cognitively normal population. Published by Elsevier Ltd.
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