title: Effects of apolipoprotein E genotype on the off-line memory consolidation.
abstract: Spontaneous brain activity or off-line activity after memory encoding is associated with memory consolidation. A few recent resting-state functional magnetic resonance imaging (RS-fMRI) studies indicate that the RS-fMRI could map off-line memory consolidation effects. However, the gene effects on memory consolidation process remain largely unknown. Here we collected two RS-fMRI sessions, one before and another after an episodic memory encoding task, from two groups of healthy young adults, one with apolipoprotein E (APOE) ε2/ε3 and the other with APOE ε3/ε4. The ratio of regional homogeneity (ReHo), a measure of local synchronization of spontaneous RS-fMRI signal, of the two sessions was used as an index of memory-consolidation. APOE ε3/ε4 group showed greater ReHo ratio within the medial temporal lobe (MTL). The ReHo ratio in MTL was significantly correlated with the recognition memory performance in the APOE ε3/ε4 group but not in ε2/ε3 group. Additionally, APOE ε3/ε4 group showed lower ReHo ratio in the occipital and parietal picture-encoding areas. Our results indicate that APOE ε3/ε4 group may have a different off-line memory consolidation process compared to ε2/ε3 group. These results may help generate future hypotheses that the off-line memory consolidation might be impaired in Alzheimer's disease.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China.
authors.forename: De-Yi
authors.initials: DY
authors.lastname: Wang
authors.forename: Xiu-Jie
authors.initials: XJ
authors.lastname: Han
authors.forename: Su-Fang
authors.initials: SF
authors.lastname: Li
authors.forename: Dong-Qiang
authors.initials: DQ
authors.lastname: Liu
authors.forename: Chao-Gan
authors.initials: CG
authors.lastname: Yan
authors.forename: Xi-Nian
authors.initials: XN
authors.lastname: Zuo
authors.forename: Chao-Zhe
authors.initials: CZ
authors.lastname: Zhu
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Vesa
authors.initials: V
authors.lastname: Kiviniemi
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Zang
mesh_terms: D001057:Apolipoproteins E / Q000235:genetics*; D001519:Behavior / Q000502:physiology; D001931:Brain Mapping; D016000:Cluster Analysis; D003710:Demography; D005260:Female; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D019579:Neocortex / Q000502:physiology; D012146:Rest / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D055815:Young Adult
chemical_list: D001057:Apolipoproteins E