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Deficits of knowledge versus executive control in semantic cognition: Insights from cued naming

Jefferies, Elizabeth (orcid.org/0000-0002-3826-4330), Patterson, Karalyn and Ralph, Matthew A. Lambon (2007) Deficits of knowledge versus executive control in semantic cognition: Insights from cued naming. Neuropsychologia. pp. 649-658. ISSN 0028-3932

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Deficits of semantic cognition in semantic dementia and in aphasia consequent on CVA (stroke) are qualitatively different. Patients with semantic dementia are characterised by progressive degradation of central semantic representations, whereas multimodal semantic deficits in stroke aphasia reflect impairment of executive processes that help to direct and control semantic activation in a task-appropriate fashion [Jefferies, E., & Lambon Ralph, M. A. (2006). Semantic impairment in stroke aphasia vs. semantic dementia: A case-series comparison. Brain 129, 2132-2147]. We explored interactions between these two aspects of semantic cognition by examining the effects of cumulative phonemic cueing on picture naming in case series of these two types of patient. The stroke aphasic patients with multimodal semantic deficits cued very readily and demonstrated near-perfect name retrieval when cumulative phonemic cues reached or exceeded the target name's uniqueness point. Therefore, knowledge of the picture names was largely intact for the aphasic patients, but they were unable to retrieve this information without cues that helped to direct activation towards the target response. Equivalent phonemic cues engendered significant but much more limited benefit to the semantic dementia patients: their naming was still severely impaired even when most of the word had been provided. In contrast to the pattern in the stroke aphasia group, successful cueing was mainly confined to the more familiar un-named pictures. We propose that this limited cueing effect in semantic dementia follows from the fact that concepts deteriorate in a graded fashion [Rogers, T. T., Lambon Ralph, M. A., Garrard, P., Bozeat, S., McClelland, J. L., & Hodges, J. R., et al. (2004). The structure and deterioration of semantic memory: A neuropsychological and computational investigation. Psychological Review 111, 205-235]. For partially degraded items, the residual conceptual knowledge may be insufficient to drive speech production to completion but these items might reach threshold when they are bolstered by cues. (C) 2007 Elsevier Ltd. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2007 Elsevier Ltd. This is an author produced version of a paper published in Neuropsychologia. Uploaded in accordance with the publisher's self-archiving policy.
Institution: The University of York
Academic Units: The University of York > Psychology (York)
Depositing User: Sherpa Assistant
Date Deposited: 04 Apr 2008 13:16
Last Modified: 21 Aug 2016 00:02
Published Version: http://dx.doi.org/10.1016/j.neuropsychologia.2007....
Status: Published
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/3725

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