This study presents the first direct comparison of immediate serial recall in semantic dementia (SD) and transcortical sensory aphasia (TSA). Previous studies of the effect of semantic impairment on verbal short-term memory (STM) have led to important theoretical advances. However, different conclusions have been drawn from these two groups. This research aimed to explain these inconsistencies. We observed (a) qualitative differences between SD and TSA in the nature of the verbal STM impairment and (b) considerable variation within the TSA group. The SD and TSA patients all had poor semantic processing and good phonology. Reflecting this, both groups remained sensitive to phonological similarity and showed a reduced effect of lexicality in immediate serial recall. The SD patients showed normal serial position effects; in contrast, the TSA patients had poor recall of the initial list items and exhibited large recency effects on longer lists. The error patterns of the two groups differed: the SD patients made numerous phoneme migration errors whereas the TSA group were more likely to produce entire words in the wrong order, often initiating recall with terminal list items. The SD cases also showed somewhat larger effects of word frequency and imageability. We propose that these contrasting performance patterns are explicable in terms of the nature of the underlying semantic impairment. SD is associated with anterior lobe atrophy and produces degradation of semantic knowledge - this is more striking for less frequent/imageable items, accentuating the effects of these lexical/semantic variables in STM. SD patients frequently recombine the phonemes of different list items due to the reduced semantic constraint upon phonology (semantic binding: Patterson et al., 1994). In contrast, the semantic impairment in TSA follows frontal or temporoparietal lesions and is associated with poor executive control of semantic processing (deregulated semantic cognition: Jefferies and Lambon Ralph, 2006), explaining why these patients are liable to recall entire words out of serial order.

中文翻译：

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语义障碍对中风失语症和语义痴呆患者言语短期记忆的影响：一项比较研究


本研究首次对语义痴呆（SD）和经皮层感觉性失语症（TSA）的即时连续回忆进行直接比较。先前关于语义障碍对言语短期记忆（STM）影响的研究已经取得了重要的理论进展。然而，这两个小组得出了不同的结论。这项研究旨在解释这些不一致之处。我们观察到 (a) SD 和 TSA 在言语 STM 损伤的性质上存在质的差异，以及 (b) TSA 组内存在相当大的差异。 SD 和 TSA 患者的语义处理能力较差，但语音能力良好。反映这一点的是，两组人都对语音相似性保持敏感，并且在立即连续回忆中表现出词汇效果的降低。 SD患者表现出正常的系列位置效应；相比之下，TSA 患者对最初的清单项目的记忆力较差，并且对较长的清单表现出较大的近因效应。两组的错误模式不同：SD 患者犯了许多音素迁移错误，而 TSA 组更有可能以错误的顺序产生整个单词，通常从末端列表项开始回忆。 SD 案例还显示出词频和形象性的更大影响。我们认为这些对比的表现模式可以根据潜在语义损伤的性质来解释。 SD 与前叶萎缩相关，并导致语义知识的退化——这对于不太频繁/可成像的项目更为显着，强调了 STM 中这些词汇/语义变量的影响。由于对音系的语义限制减少，SD 患者经常重新组合不同列表项的音素（语义绑定：Patterson 等，1994）。 相比之下，TSA 中的语义障碍发生在额叶或颞顶病变之后，并且与语义处理的执行控制不良有关（解除管制的语义认知：Jefferies 和 Lambon Ralph，2006），这解释了为什么这些患者容易不按顺序回忆起整个单词。 。