Knowledge of living, nonliving and “sensory quality” categories in semantic dementia (original) (raw)
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SEMANTIC DEMENTIA WITH CATEGORY SPECIFICITY:ACOMPARATIVE CASE-SERIES STUDY
Cognitive Neuropsychology, 2003
Patients with semantic dementia, the temporal variant of frontotemporal dementia, are relevant to both the neuroanatomical and neuropsychological debates in the category-specific literature. These patients present with a selective and progressive semantic deficit consequent on circumscribed atrophy of the inferolateral polar temporal lobes bilaterally, including the inferotemporal gyrus. In this study, a patient KH with a significant advantage for artefacts over living things was compared to five other semantic dementia patients with commensurate levels of semantic impairment. KH demonstrated a consistent category difference in favour of artefacts across all the expressive and receptive semantic tests. This difference was reliable even when familiarity, frequency, and other potential confounding factors were controlled. While KH demonstrated an association between poor knowledge of sensory attributes and a consistently greater impairment on living things than artefacts, the other patients did not. As observed in a number of previous studies, all five of the patients, contrasted to KH, exhibited an advantage for functional/associative over sensory attributes but without demonstrating the category-specific deficit that the sensory-functional theory (and the locus of their atrophy) might predict.
Journal of Cognitive Neuroscience, 2001
& Two types of theoretical account have been proposed to explain the phenomenon of category-specific impairment in tests of semantic memory: One stresses the importance of different cortical regions to the representation of living and nonliving categories, while the other emphasize the importance of statistical relationships among features of concepts belonging to these two broad semantic domains. Theories of the latter kind predict that the direction of a domain advantage will be determined in large part by the overall damage to the semantic system, and that the profiles of patients with progressive impairments of semantic memory are likely to include a point at which an advantage for one domain changes to an advantage for the other. The present series of three studies employed semantic test data from two separate cohorts of patients with probable dementia of Alzheimer's type (DAT) to look for evidence of such a crossover. In the first study, longitudinal test scores from a cohort of 58 patients were examined to confirm the presence of progressive semantic deterioration in this group. In the second study, Kaplan-Meier survival curves based on serial naming responses and plotted separately for items belonging to living and nonliving domains indicated that the representations of living concepts (as measured by naming) deteriorated at a consistently and significantly faster rate than those of nonliving concepts. A third study, carried out to look in detail at the performance of mildly affected patients, employed an additional cross-sectional cohort of 20 patients with mild DAT and utilized a graded naming assessment. This study also revealed no evidence for a crossover in the advantage of one domain over the other as a function of disease severity. Taken together with the model of anatomical progression in DAT based on the work of , these findings are interpreted as evidence for the importance of regional cerebral anatomy to the genesis of semantic domain effects in DAT. & D
Relative category-specific preservation in semantic dementia? Evidence from 35 cases
Brain and Language, 2013
Category-specific deficits have rarely been reported in semantic dementia (SD). To our knowledge, only four previous studies have documented category-specific deficits, and these have focused on the living versus non-living things contrast rather than on more fine-grained semantic categories. This study aimed to determine whether a category-specific effect could be highlighted by a semantic sorting task administered to 35 SD patients once at baseline and again after 2 years and to 10 Alzheimer's disease patients (AD). We found a relative preservation of fruit and vegetables only in SD.
A Predominance of Category Deficits for Living Things In Alzheimer's Disease and Lewy Body Dementia
Journal of the …, 2007
Although semantic memory impairment is well documented in patients with dementia of the Alzheimer’s type, questions remain as to whether the deficit extends to other forms of dementia and whether it differentially affects different domains of knowledge. We examined category naming on two tasks (picture naming and naming-to-description) in patients with Alzheimer’s disease (AD: n =11), Lewy body dementia (DLB: n =11) and healthy elderly matched controls (n =22). The DLB and AD groups showed significantly worse naming on both tasks, although the AD patients were more impaired than the DLB patients. Like some AD patients, some DLB patients showed evidence of category-specific naming deficits, and strikingly, all 25 significant category dissociations were for living things. The latter finding accords with the preponderance of living deficits previously documented for AD patients, but extends this finding to DLB patients. The implications of this category bias is discussed in relation to relevant models of category specificity
Category specific semantic loss in dementia of Alzheimer’s type
2000
In the context of focal brain injury, selective loss of semantic knowledge in the domain of either natural kinds or artefacts is usually considered to reflect the differential importance of temporal and frontoparietal regions to the representations of perceptual and functional attributes, respectively. It is harder to account for as a feature of a more diffuse process, and previous cross-sectional analyses of patients with dementia of Alzheimer's type (DAT) have differed over whether category effects occur. In our series of 58 patients with probable DAT, we demonstrated a significant group advantage for artefacts, and explored possible reasons for the inconsistency of this finding in other studies. A multiple single-case strategy revealed not only individuals with consistent advantages for
Neuropsychologia, 1997
We studied the relationship between naming and semantic memory in a group of 10 patients with dementia of Alzheimer's type. In an extension to a previous cross-sectional study (Hodges, J. R. et al., Brain and Language, 1996, 54, 302 325), this relationship was investigated at two longitudinal points within each patient's cognitive decline. Two types of naming performance were compared: items that each patient named correctly at the first stage but failed to name at the second stage, as contrasted with items named correctly at both stages Ithereby providing a control for cognitive decline in general), Semantic knowledge of the concepts represented by the pictures in the naming test was investigated at each stage using definitions to the spoken object name, scored particularly for the number o1" sensory and associative/functional features provided by the patient.
Neuropsychologia, 2003
The breakdown of semantic knowledge relative to living and non-living categories was studied in patients with Alzheimer's disease (AD). The same living and non-living items were used in a semantic battery and in a semantic priming paradigm exploring automatic access to the semantic system. Although AD patients showed a semantic deficit on the intentional semantic battery, they demonstrated normal semantic facilitation on the priming task. In the AD group as a whole, the semantic impairment did not preferentially affect the living category either in the intentional or automatic condition. Instead, a prevalent deficit for the living category was found in three AD patients (14% of the group) on the intentional semantic tasks, but not on the automatic one. These findings support the view that the category effect may not be a generalised phenomenon in AD but may be restricted to a limited number of patients. The intentional/automatic dissociation of the semantic breakdown demonstrated by AD patients is discussed in relation to different theories regarding the organisation of semantic memory.
Semantic memory in Alzheimer's disease: Representativeness, ontologic category, and material
Neuropsychology, 1998
Alzheimer's disease (AD) patients with semantic memory difficulty and AD patients with relatively preserved semantic memory named pictures and judged the category membership of words and pictures of natural kinds and manufactured artifacts that varied in their representativeness. Only semantically impaired patients were insensitive to representativeness in their category judgments. AD subgroup judgments did not differ for natural kinds compared to manufactured artifacts nor for words compared to pictures. AD subgroup differences could not be explained by dementia severity, memory, reading, and visuoperception. The similarity process for relating coordinate members of a taxonomic category contributes to the normal appreciation of word and picture meaning, and this process is compromised in AD patients with semantic difficulty. Semantic memory is the long-term mental representation of the meaning underlying verbal and nonverbal representations of a concept (Jackendoff, 1983; Tulving, 1972). Many reports over the past two decades have observed deficits on tasks requiring semantic memory in patients with probable Alzheimer's disease (AD), such as naming and judging the semantic category of a test object (Bayles, Tomoeda, &
Brain, 2006
A novel, non-verbal test of semantic feature knowledge is introduced, enabling subordinate knowledge of four important concept attributes-colour, sound, environmental context and motion-to be individually probed. This methodology provides more specific information than existing non-verbal semantic tests about the status of attribute knowledge relating to individual concept representations. Performance on this test of a group of 12 patients with semantic dementia (10 male, mean age: 64.4 years) correlated strongly with their scores on more conventional tests of semantic memory, such as naming and word-to-picture matching. The test's overlapping structure, in which individual concepts were probed in two, three or all four modalities, provided evidence of performance consistency on individual items between feature conditions. Group and individual analyses revealed little evidence for differential performance across the four feature conditions, though sound and colour correlated most strongly, and motion least strongly, with other semantic tasks, and patients were less accurate on the motion features of living than non-living concepts (with no such conceptual domain differences in the other conditions). The results are discussed in the context of their implications for the place of semantic dementia within the classification of progressive aphasic syndromes, and for contemporary models of semantic representation and organization.