MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Cogn Neuropsychol. 2000 Jul 1;17(5):437-65. doi: 10.1080/026432900410784.
Many patients with progressive fluent aphasia present with poor verbal comprehension and profound word-finding difficulties in the context of much better picture comprehension and object use. The Japanese term Gogi (literally "word-meaning") aphasia matches this behavioural pattern. The alternative label of semantic dementia is most often used for these patients and this term emphasises a generalised degradation of conceptual knowledge that encompasses both verbal and nonverbal comprehension. The study presented here investigates whether progressive fluent aphasia has a functional impairment limited to the verbal domain (Gogi aphasia) or more widespread involvement of all conceptual knowledge (semantic dementia). We report data collected from a patient with progressive fluent aphasia, IW, who presented with profound word-finding difficulties and relatively poor word comprehension. The predictions of three theoretical interpretations of this pattern are investigated in a series of experimental tasks. We argue that IW's poor verbal comprehension and anomia cannot easily be explained as an impairment to either a semantic lexicon or a modality-specific verbal semantic system. Instead we favour an explanation in terms of a single impairment to a unitary semantic system within a framework that emphasises the underlying differences in the mapping between surface form and meaning, for words and pictures. We demonstrate how IW's pattern of data can be replicated in an implemented connectionist network that includes a systematic mapping for pictures but an arbitrary relationship for words. We conclude that although Gogi aphasia may be an accurate clinical description of the most striking features observed in progressive fluent aphasia, the disorder is primarily a progressive loss of conceptual knowledge-it is semantic dementia.
许多进展性流利性失语症患者表现出严重的言语理解障碍和严重的找词困难，但图片理解和物体使用能力较好。日语术语“言语意义障碍（Gogi）”与这种行为模式相匹配。这些患者通常使用“语义痴呆”这一替代标签，这个术语强调了概念知识的全面退化，包括言语和非言语理解。本研究旨在探讨进展性流利性失语症是否仅存在于言语领域的功能障碍（Gogi 失语症），还是更广泛地涉及所有概念知识（语义痴呆）。我们报告了一名进展性流利性失语症患者 IW 的数据，该患者表现出严重的找词困难和相对较差的词语理解能力。我们通过一系列实验任务研究了三种理论解释的预测。我们认为，IW 的言语理解能力差和命名障碍不能简单地解释为语义词汇或特定于模态的言语语义系统的损伤。相反，我们倾向于用单一的语义系统损伤来解释，这个系统强调了词和图片之间的表面形式和意义之间的映射的潜在差异。我们展示了如何在一个实现的连接主义网络中复制 IW 的数据模式，该网络包括图片的系统映射，但词的映射是任意的。我们的结论是，尽管 Gogi 失语症可能是进展性流利性失语症中最显著特征的准确临床描述，但该障碍主要是概念知识的进行性丧失——它是语义痴呆。
