认知老化的神经机制及假说

摘要

在认知老化的过程中,大脑的结构和功能均会发生不同程度的变化.自20世纪70年代以来,脑成像技术已成为研究认知老化神经机制的重要手段.任务态功能影像学研究发现老年人局部脑区的两种过度“激活”现象:老年人大脑半球非对称性减弱模型(HAROLD)和老化中由后向前转移模型(PASA).文章回顾了与这两个模型相关的理论假说,包括代偿说(compensation theory)和去分化说(dedifferentiation theory),从不同方面来解释认知老化的神经机制.%During the course of cognitive aging,the structure and function of brain change at different levels.Brain imaging techniques have become important means for the neural mechanism research of cognitive aging since 1970s.Functional imaging studies have consistently found two "overactivation" models in regional brain area in the elderly:hemispheric asymmetry reduction in older adults (HAROLD) and posterior-anterior shift in aging (PASA).The theories and hypothesis relating to the two models,including compensation theory and dedifferentiation theory are reviewed,and the neural mechanism of cognitive aging is explained from different aspects in this paper.