Semantic dementia: a form of circumscribed cerebral atrophy

Snowden, Julie S.

doi:10.1093/neucas/1.1.39-y

Cited by 356 publications

(458 citation statements)

References 21 publications

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“…There is compelling evidence to consider that this syndrome, termed either temporal variant of frontotemporal dementia [18,35] or semantic dementia (SD) [70], is part of the disease spectrum of frontotemporal lobar degeneration (FTLD). Although FTLD is a relatively common cause of dementia, accounting for about 20% of cases of dementia with presenile onset, most of cases suffer from the frontal variant of FTD, while the temporal variant is a relatively rare disorder [61].…”

Section: Introductionmentioning

confidence: 99%

“…Although FTLD is a relatively common cause of dementia, accounting for about 20% of cases of dementia with presenile onset, most of cases suffer from the frontal variant of FTD, while the temporal variant is a relatively rare disorder [61]. This disease is characterized by progressive loss of semantic knowledge and relative preservation of grammatical aspects of language, visuospatial skills and day-to-day memory [31,70], although episodic memory, when specifically assessed, can be impaired [35].…”

Section: Introductionmentioning

confidence: 99%

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Anatomical and functional alterations in semantic dementia: A voxel-based MRI and PET study

Desgranges

Matuszewski

Piolino

et al. 2007

Neurobiology of Aging

137

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Rare studies have used MRI and voxel based morphometry (VBM) to assess atrophy, and only two PET studies used SPM to examine functional changes in semantic dementia (SD). Our aim was to highlight both morphological and functional abnormalities in a same group of 10 SD patients, in the entire brain, using a "state of the art" methodology (optimized VBM procedure, PET data corrected for partial volume effects and voxel based analyses). We also used an extensive neuropsychological battery. We showed that main alterations concerned the left temporal lobe, in accordance with the striking impairment of semantic memory in SD patients, as well as the hippocampal region, which may partly explain their moderate episodic memory deficits. Hypometabolism was more extensive than grey matter loss in both temporal lobes, and specifically concerned the orbitofrontal areas, consistent with the moderate impairment of executive functions and behavioural changes. While PET is more sensitive than MRI, there is striking concordance between morphological and functional abnormalities, which contrast with the discordance observed in Alzheimer"s disease and might be a typical feature of SD.3

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anatomical and functional alterations in semantic dementia: A voxel-based MRI and PET study

Desgranges

Matuszewski

Piolino

et al. 2007

Neurobiology of Aging

137

View full text Add to dashboard Cite

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“…The second literature concerns the gradual erosion of conceptual knowledge in a progressive neurological condition called semantic dementia (SD; Hodges, Garrard, & Patterson, 1998;Snowden, Goulding, & Neary, 1989). Patients with SD exhibit a progressive and eventually profound deterioration of knowledge about the meanings of words and objects, together with a remarkable sparing of many other cognitive abilities until late in the course of the disease .…”

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confidence: 99%

Object categorization: Reversals and explanations of the basic-level advantage.

Rogers

Patterson²

2007

Journal of Experimental Psychology: General

165

163

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People are generally faster and more accurate to name or categorize objects at the basic level (e.g., dog) relative to more general (animal) or specific (collie) levels, an effect replicated in Experiment 1 for categorization of object pictures. To some, this pattern suggests a dual-process mechanism, in which objects first activate basic-level categories directly and later engage more general or specific categories through the spread of activation in a processing hierarchy. This account is, however, challenged by data from Experiment 2 showing that neuropsychological patients with impairments of conceptual knowledge categorize more accurately at superordinate levels than at the basic level-suggesting that knowledge about an object's general nature does not depend on prior basic-level categorization. The authors consider how a parallel distributed processing theory of conceptual knowledge can reconcile the apparent discrepancy. This theory predicts that if healthy individuals are encouraged to make rapid categorization responses, the usual basic Ͼ general advantage should also reverse, a prediction tested and confirmed in Experiment 3. Implications for theories of visual object recognition are discussed.

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“…19 Due to atrophy in the dominant anterior temporal pole (Case 5-2), patients with semantic variant PPA demonstrate anomia and single-word comprehension deficits and may ask what words mean (ie, ''What is spaghetti?''). While fluency and grammar are generally maintained, speech becomes increasingly empty, with vague words or jargon phrases replacing specific nouns and verbs ( Table 5- …”

Section: Continued From Page 468mentioning

confidence: 99%