Considering the role of semantic memory in episodic future thinking: evidence from semantic dementia
Considering the role of semantic memory in episodic future thinking: evidence from semantic dementia
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DOI：
10.1093/brain/aws119
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发表时间：
2012-07-01
期刊：
影响因子：
14.5
通讯作者：
Piguet, Olivier
中科院分区：
文献类型：
--
作者：
Irish, Muireann;Addis, Donna Rose;Piguet, Olivier
语义痴呆是一种进行性神经退行性疾病，其特征是在相对保存的情景记忆的背景下语义记忆的深度和非模态丧失。相比之下，阿尔茨海默病患者通常表现出情景记忆障碍，但语义缺陷的程度比语义痴呆症要轻得多。在过去的十年里，我们对这些人群的情景记忆检索的理解大大增加，然而，我们对这些患者想象和描述可能的未来事件的能力以及情景未来思维是否是由取决于痴呆亚型的不同神经基质介导的知之甚少。在这里，我们探讨了语义性痴呆 (n = 11) 和阿尔茨海默病 (n = 11) 患者的情景未来思维，并与健康对照参与者 (n = 10) 进行比较。参与者完成了一系列旨在探索过去和未来条件下的情景和语义思维的测试，以及情景和语义记忆的标准化测试。此外，所有参与者都接受了磁共振成像。尽管语义痴呆群体对最近发生的事件的情景检索相对完整，但他们对情景未来思维的能力却表现出显着的损害。相比之下，患有阿尔茨海默病的人在过去和未来的突发状况中表现出平行的缺陷。基于体素的形态测量分析证实，左颞下回和双侧颞极（与语义记忆密切相关的区域）的萎缩与语义痴呆中情景未来思维的缺陷显着相关。相反，阿尔茨海默病患者的情景未来思维表现与情景记忆相关区域（即后扣带回、海马旁回和额极）的萎缩相关。通过相关分析进一步限定了痴呆组的这些不同的神经解剖学基础，证实了语义痴呆中语义记忆缺陷和情景未来思维之间的关系，与阿尔茨海默病中情景记忆缺陷和情景未来思维的作用形成鲜明对比。我们的研究结果表明，语义知识对于构建新颖的未来事件至关重要，它提供了将情景细节整合到其中的必要支架。需要进一步的研究来阐明语义记忆对未来思维的精确贡献，并探索自我投射的缺陷如何在不同痴呆亚型的行为和社会层面上表现出来。
Semantic dementia is a progressive neurodegenerative condition characterized by the profound and amodal loss of semantic memory in the context of relatively preserved episodic memory. In contrast, patients with Alzheimer's disease typically display impairments in episodic memory, but with semantic deficits of a much lesser magnitude than in semantic dementia. Our understanding of episodic memory retrieval in these cohorts has greatly increased over the last decade, however, we know relatively little regarding the ability of these patients to imagine and describe possible future events, and whether episodic future thinking is mediated by divergent neural substrates contingent on dementia subtype. Here, we explored episodic future thinking in patients with semantic dementia (n = 11) and Alzheimer's disease (n = 11), in comparison with healthy control participants (n = 10). Participants completed a battery of tests designed to probe episodic and semantic thinking across past and future conditions, as well as standardized tests of episodic and semantic memory. Further, all participants underwent magnetic resonance imaging. Despite their relatively intact episodic retrieval for recent past events, the semantic dementia cohort showed significant impairments for episodic future thinking. In contrast, the group with Alzheimer's disease showed parallel deficits across past and future episodic conditions. Voxel-based morphometry analyses confirmed that atrophy in the left inferior temporal gyrus and bilateral temporal poles, regions strongly implicated in semantic memory, correlated significantly with deficits in episodic future thinking in semantic dementia. Conversely, episodic future thinking performance in Alzheimer's disease correlated with atrophy in regions associated with episodic memory, namely the posterior cingulate, parahippocampal gyrus and frontal pole. These distinct neuroanatomical substrates contingent on dementia group were further qualified by correlational analyses that confirmed the relation between semantic memory deficits and episodic future thinking in semantic dementia, in contrast with the role of episodic memory deficits and episodic future thinking in Alzheimer's disease. Our findings demonstrate that semantic knowledge is critical for the construction of novel future events, providing the necessary scaffolding into which episodic details can be integrated. Further research is necessary to elucidate the precise contribution of semantic memory to future thinking, and to explore how deficits in self-projection manifest on behavioural and social levels in different dementia subtypes.