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The contribution of executive control to semantic cognition: Convergent evidence from semantic aphasia and executive dysfunction

Thompson, Hannah, Almaghyuli, Azizah, Noonan, Krist A., barak, Ohr, Lambon Ralph, Matthew A. and Jefferies, Elizabeth (2018) The contribution of executive control to semantic cognition: Convergent evidence from semantic aphasia and executive dysfunction Journal of Neuropsychology.

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Abstract

Semantic cognition, as described by the controlled semantic cognition (CSC) framework (Rogers et al., 2015, 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.

Item Type: Article
Divisions : Faculty of Health and Medical Sciences > School of Psychology
Authors :
NameEmailORCID
Thompson, Hannahh.thompson@surrey.ac.uk
Almaghyuli, Azizah
Noonan, Krist A.
barak, Ohr
Lambon Ralph, Matthew A.
Jefferies, Elizabeth
Date : 3 January 2018
Funders : Medical Research Council (MRC)
Identification Number : 10.1111/jnp.12142
Copyright Disclaimer : © 2018 The Authors. Journal of Neuropsychology published by John Wiley & Sons Ltd on behalf of British Psychological Society This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords : Aphasia; Control; Executive dysfunction; Semantic
Depositing User : Clive Harris
Date Deposited : 12 Feb 2018 14:15
Last Modified : 14 Mar 2018 14:38
URI: http://epubs.surrey.ac.uk/id/eprint/845816

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