Neural basis for semantic memory difficulty in Alzheimer's disease: an fMRI study
Neural basis for semantic memory difficulty in Alzheimer's disease: an fMRI study
复制标题
DOI：
10.1093/brain/awg027
复制
发表时间：
2003-02-01
期刊：
影响因子：
14.5
通讯作者：
Gee, J
中科院分区：
文献类型：
--
作者：
Grossman, M;Koenig, P;Gee, J
可能患有阿尔茨海默病的患者被认为有语义记忆缺陷。我们使用功能性MRI评估了11例阿尔茨海默病患者和16名健康老年人的动物和工具语义记忆受损的神经基础。对于这两类知识，与健康的老年人相比，阿尔茨海默病患者的左后外侧颞下顶叶皮层的激活程度降低。这个异模关联区域的激活变化可能与类别中性语义过程的损伤有关，这些语义过程涉及整合特定模态关联皮层中表征的特征知识。我们还发现，在阿尔茨海默氏症患者中，左侧颞叶皮层的一个区域对两类知识的激活有所增加，而在健康老年人中则没有。与健康老年人相比，阿尔茨海默病患者的类别特异性变化也被观察到，这可能与语义记忆中类别特异性特征知识的神经表征有关。对于动物来说，阿尔茨海默病患者的左腹颞叶皮层在解剖学分布上被激活，这一分布在健康老年人的左腹后部。对于IMPLEMENTS来说，阿尔茨海默病患者的额纹状体区域被激活的方式与健康老年人的这类招募位点不同。我们的研究结果与语义记忆的双组分模型一致，该模型涉及类别中性过程对特定类别知识的操作，并且这两个组分似乎在阿尔茨海默病中受到损害。语义记忆基础的大规模神经网络的组成部分可能在面对神经退行性疾病时修改自己以保持其性能。
Patients with probable Alzheimer's disease are thought to have a semantic memory deficit. We used functional MRI to evaluate the neural basis for impaired semantic memory for ANIMALS and IMPLEMENTS in 11 patients with Alzheimer's disease and 16 healthy seniors. For both categories of knowledge, Alzheimer's disease patients show reduced activation in the left posterolateral temporal-inferior parietal cortex compared with healthy seniors. Activation changes in this heteromodal association region may be related to an impairment of the category-neutral semantic processes involved in integrating feature knowledge that is represented in modality-specific association cortices. We also found increased activation of an area of the left temporal cortex for both categories of knowledge in Alzheimer's disease that was not activated in healthy seniors. Category-specific changes were also seen in Alzheimer's disease compared with healthy seniors that may be related to the neural representation of category-specific feature knowledge represented in semantic memory. For ANIMALS, the left ventral temporal cortex was activated in Alzheimer's disease in an anatomical distribution that was posterior to the left ventral recruitment for this category in healthy seniors. For IMPLEMENTS, frontal-striatal regions were activated in Alzheimer's disease in a manner that was displaced from the locus of recruitment for this category in healthy seniors. Our findings are consistent with a two-component model of semantic memory involving category-neutral processes operating on category-specific knowledge, and both components appear to be compromised in Alzheimer's disease. Components of the large-scale neural network underlying semantic memory may modify themselves to maintain performance in the face of a neurodegenerative disease.