Cognitive and anatomic double dissociation in the representation of concrete and abstract words in semantic variant and behavioral variant frontotemporal degeneration. (April 2016)

• Record Type: Journal Article
• Authors: Cousins, Katheryn A.Q.; York, Collin; Bauer, Laura; Grossman, Murray
• Is Part Of: Neuropsychologia. Volume 84(2016)
• Page Start: 244
• Page End: 251
• Publication Date: 2016-04
• Subjects: Semantic memory -- Abstract -- Concrete -- svPPA -- bvFTD; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2016.02.025
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: We examine the anatomic basis for abstract and concrete lexical representations in semantic memory by assessing patients with focal neurodegenerative disease. Prior evidence from healthy adult studies suggests that there may be an anatomical dissociation between abstract and concrete representations: abstract words more strongly activate the left inferior frontal gyrus relative to concrete words, while concrete words more strongly activate left anterior-inferior temporal regions. However, this double dissociation has not been directly examined. We test this dissociation in two patient groups with focal cortical atrophy in each of these regions, the behavioral variant of Frontotemporal Degeneration (bvFTD) and the semantic variant of Primary Progressive Aphasia (svPPA). We administered an associativity judgment task for abstract and concrete words, where subjects select which of two words is best associated with a given target word. Both bvFTD and svPPA patients were significantly impaired in their overall performance compared to controls. While controls treated concrete and abstract words equally, we found a category-specific double dissociation in patients' judgments: bvFTD patients showed a concreteness effect (CE), with significantly worse performance for abstract compared to concrete words, while svPPA patients showed reversal of the CE, with significantly worse performance for concrete over abstract words. Regression analyses also revealed an anatomic double dissociation: The CE is associated with inferior frontal atrophy in bvFTD, while reversal of the CE is associated with left anterior-inferior temporal atrophy in svPPA. These results support a cognitive and anatomic model of semantic memory organization where abstract and concrete representations are supported by dissociable neuroanatomic substrates. Highlights: The anatomical representations of abstract and concrete concepts are investigated. Tested two patient groups, svPPA and bvFTD, with atrophy to theoretically critical neural regions. A two-alternative forced choice task was administered, using concrete and abstract noun stimuli. svPPA patients had worse concrete word knowledge, related to the left inferior temporal gyrus. bvFTD patients had worse abstract word processing, related to the inferior frontal gyrus.