Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, P.O. Box 9101 6500 HB Nijmegen, The Netherlands.
Neuroimage. 2010 Oct 15;53(1):331-40. doi: 10.1016/j.neuroimage.2010.05.082. Epub 2010 Jun 4.
With aging, the content of self-reported autobiographical memories shifts from episodic to semantic. Onset of Alzheimer's disease enhances this pattern, but the neural underpinnings of this change in Autobiographical Memory (AM), in particular the role of hippocampal degradation, are unknown. We employed fMRI contrasting autobiographical and semantic retrieval, in 22 healthy elderly and 21 Alzheimer's patients. The shift towards semantic characteristics in AM retrieval was indeed enhanced in patients. Both groups activated brain regions commonly involved in AM retrieval, including occipital association areas, medial temporal lobes, lateral temporal and midline prefrontal areas. When compared to controls, Alzheimer's patients showed enhanced activity in the left inferior frontal gyrus (LIFG), ventromedial prefrontal cortex (vmPFC), right precuneus and left lingual gyrus. Activation of LIFG and vmPFC was significantly negatively correlated with hippocampal volume in patients only. Thus, we speculate that the linking function of the degraded hippocampus is taken over by the vmPFC; a shift recently observed during normal consolidation. This potentially compensatory process may support early Alzheimer's detection or prognosis.
随着年龄的增长，自我报告的自传体记忆的内容从情景记忆转变为语义记忆。阿尔茨海默病的发病增强了这种模式，但自传体记忆 (AM) 变化的神经基础，特别是海马体退化的作用尚不清楚。我们在 22 名健康老年人和 21 名阿尔茨海默病患者中使用 fMRI 对比自传体和语义检索。患者的 AM 检索确实向语义特征转变增强。两组均激活了通常涉及 AM 检索的大脑区域，包括枕叶联合区、内侧颞叶、外侧颞叶和中线前额叶区域。与对照组相比，阿尔茨海默病患者的左侧额下回 (LIFG)、腹内侧前额叶皮层 (vmPFC)、右侧顶叶内囊和左侧舌回的活动增强。仅在患者中，LIFG 和 vmPFC 的激活与海马体体积呈显著负相关。因此，我们推测退化的海马体的连接功能被 vmPFC 接管；这是在正常巩固过程中最近观察到的转变。这个潜在的补偿过程可能有助于早期阿尔茨海默病的检测或预后。
