Thompson Hannah E, Almaghyuli Azizah, Noonan Krist A, Barak Ohr, Lambon Ralph Matthew A, Jefferies Elizabeth
School of Psychology, University of Surrey, UK.
Department of Psychology and York Neuroimaging Centre, University of York, UK.
J Neuropsychol. 2018 Jun;12(2):312-340. doi: 10.1111/jnp.12142. Epub 2018 Jan 3.
Semantic cognition, as described by the controlled semantic cognition (CSC) framework (Rogers et al., , Neuropsychologia, 76, 220), involves two key components: activation of coherent, generalizable concepts within a heteromodal 'hub' in combination with modality-specific features (spokes), and a constraining mechanism that manipulates and gates this knowledge to generate time- and task-appropriate behaviour. Executive-semantic goal representations, largely supported by executive regions such as frontal and parietal cortex, are thought to allow the generation of non-dominant aspects of knowledge when these are appropriate for the task or context. Semantic aphasia (SA) patients have executive-semantic deficits, and these are correlated with general executive impairment. If the CSC proposal is correct, patients with executive impairment should not only exhibit impaired semantic cognition, but should also show characteristics that align with those observed in SA. This possibility remains largely untested, as patients selected on the basis that they show executive impairment (i.e., with 'dysexecutive syndrome') have not been extensively tested on tasks tapping semantic control and have not been previously compared with SA cases. We explored conceptual processing in 12 patients showing symptoms consistent with dysexecutive syndrome (DYS) and 24 SA patients, using a range of multimodal semantic assessments which manipulated control demands. Patients with executive impairments, despite not being selected to show semantic impairments, nevertheless showed parallel patterns to SA cases. They showed strong effects of distractor strength, cues and miscues, and probe-target distance, plus minimal effects of word frequency on comprehension (unlike semantic dementia patients with degradation of conceptual knowledge). This supports a component process account of semantic cognition in which retrieval is shaped by control processes, and confirms that deficits in SA patients reflect difficulty controlling semantic retrieval.
如受控语义认知（CSC）框架（罗杰斯等人，《神经心理学》，第76卷，第220页）所述，语义认知涉及两个关键组成部分：在异模态“枢纽”内激活连贯、可概括的概念，并结合特定模态特征（辐条），以及一种约束机制，该机制操纵并控制这些知识以产生符合时间和任务要求的行为。执行语义目标表征在很大程度上由额叶和顶叶皮质等执行区域支持，被认为在这些表征适合任务或情境时能够产生知识的非主导方面。语义性失语（SA）患者存在执行语义缺陷，且这些缺陷与一般执行功能障碍相关。如果CSC的提议是正确的，那么执行功能障碍患者不仅应表现出语义认知受损，还应表现出与SA患者观察到的特征相符的特点。这种可能性在很大程度上尚未得到检验，因为基于表现出执行功能障碍（即患有“执行功能障碍综合征”）而挑选出的患者尚未在涉及语义控制的任务上进行广泛测试，也未与SA病例进行过比较。我们使用一系列操纵控制要求的多模态语义评估方法，对12名表现出与执行功能障碍综合征（DYS）一致症状的患者和24名SA患者的概念加工进行了探究。尽管执行功能障碍患者并非因表现出语义损伤而被挑选，但他们仍表现出与SA病例相似的模式。他们表现出干扰物强度、线索和错误线索以及探测目标距离的强烈影响，而单词频率对理解的影响极小（与概念知识退化的语义性痴呆患者不同）。这支持了一种语义认知的成分加工观点，即检索由控制过程塑造，并证实了SA患者的缺陷反映了控制语义检索的困难。
