Semantic dementia (SD) implicates the anterior temporal lobes (ATL) as a critical substrate for semantic memory. Multi-modal semantic impairment can also be a feature of post-stroke aphasia (referred to here as “semantic aphasia” or SA) where patients show impaired regulatory control accompanied by lesions to the frontal and/or temporo-parietal cortices, and thus the two patient groups demonstrate qualitatively different patterns of semantic impairment [1]. Previous comparisons of these two patient groups have tended to focus on verbal receptive tasks. Accordingly, this study investigated nonverbal receptive abilities via a comparison of reality decision judgements in SD and SA. Pictures of objects were presented alongside non-real distracters whose features were altered to make them more/less plausible for the semantic category. The results highlighted a number of critical differences between the two groups. Compared to SD patients, SA patients: (1) were relatively unimpaired on the two alternative forced choice (2AFC) decisions despite showing a comparable degree of semantic impairment on other assessments; (2) showed minimal effects of the plausibility manipulation; (3) were strongly influenced by variations in the regulatory requirements of tasks; and (4) exhibited a reversed effect of familiarity–i.e., better performance on less commonly encountered items. These results support a distinction between semantic impairments which arise from impaired regulatory processes (e.g., SA) versus those where degraded semantic knowledge is the causal factor (e.g., SD). SA patients performed relatively well because the task structure reduced the requirement for internally generated control. In contrast, SD patients performed poorly because their degraded knowledge did not allow the fine-grained distinctions required to complete the task.

中文翻译：

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证明语义失语症和语义痴呆之间的质量差异：非语言语义处理的新探索。

语义性痴呆 (SD) 暗示前颞叶 (ATL) 作为语义记忆的关键基础。多模态语义障碍也可能是卒中后失语症（此处称为“语义性失语症”或 SA）的一个特征，其中患者表现出调节控制受损并伴有额叶和/或颞顶叶皮质损伤，因此两个患者组表现出本质上不同的语义障碍模式 [1]。之前对这两个患者组的比较往往侧重于语言接受任务。因此，本研究通过比较 SD 和 SA 中的现实决策判断来调查非语言接受能力。物体的图片与非真实的干扰物一起呈现，这些干扰物的特征被改变，使它们在语义类别中更加/不可信。结果突出了两组之间的许多关键差异。与 SD 患者相比，SA 患者：(1) 尽管在其他评估中表现出相当程度的语义障碍，但在两种替代强迫选择 (2AFC) 决定上相对未受影响；(2) 显示出合理性操作的最小影响；(3) 受任务监管要求变化的强烈影响；(4) 表现出熟悉的反向效果——即，在不太常见的项目上表现更好。这些结果支持区分由受损的调节过程（例如，SA）引起的语义障碍与那些以退化的语义知识为因果因素（例如，SD）的语义障碍之间的区别。SA 患者表现相对较好，因为任务结构减少了对内部生成控制的要求。相比之下，SD 患者表现不佳，因为他们退化的知识不允许完成任务所需的细粒度区分。