Cases reported "Aphasia"

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1/10. Preserved visual lexicosemantics in global aphasia: a right-hemisphere contribution?

    Extensive testing of a patient, GP, who encountered large-scale destruction of left-hemisphere (LH) language regions was undertaken in order to address several issues concerning the ability of nonperisylvian areas to extract meaning from printed words. Testing revealed recognition of superordinate boundaries of animals, tools, vegetables, fruit, clothes, and furniture. GP was able to distinguish proper names from other nouns and from nonwords. GP was also able to differentiate words representing living things from those denoting nonliving things. The extent of LH infarct resulting in a global impairment to phonological and syntactic processing suggests LH specificity for these functions but considerable right-hemisphere (RH) participation in visual lexicosemantic processing. The relative preservation of visual lexicosemantic abilities despite severe impairment to all aspects of phonological coding demonstrates the importance of the direct route to the meaning of single printed words.
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keywords = animal
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2/10. Neural subsystems for object knowledge.

    Critical issues in the cognitive neuroscience of language are whether there are multiple systems for the representation of meaning, perhaps organized by processing system (such as vision or language), and whether further subsystems are distinguishable within these larger ones. We describe here a patient (K.R.) with cerebral damage whose pattern of acquired deficits offers direct evidence for a major division between visually based and language-based higher-level representations, and for processing subsystems within language. K.R. could not name animals regardless of the type of presentation (auditory or visual), but had no difficulty naming other living things and objects. When asked to describe verbally the physical attributes of animals (for example, 'what colour is an elephant?'), she was strikingly impaired. Nevertheless, she could distinguish the correct physical attributes of animals when they were presented visually (she could distinguish animals that were correctly coloured from those that were not). Her knowledge of input stimulus. To explain this selective deficit, these data mandate the existence of two distinct representations of such properties in normal individuals, one visually based and one language-based. Furthermore, these data establish that knowledge of physical attributes is strictly segregated from knowledge of other properties in the language system.
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keywords = animal
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3/10. Semantic dementia. Progressive fluent aphasia with temporal lobe atrophy.

    We report five patients with a stereotyped clinical syndrome characterized by fluent dysphasia with severe anomia, reduced vocabulary and prominent impairment of single-word comprehension, progressing to a stage of virtually complete dissolution of the semantic components of language. A marked reduction in the ability to generate exemplars from restricted semantic categories (e.g. animals, vehicles, etc.) was a consistent and early feature. Tests of semantic memory demonstrated a radically impoverished knowledge about a range of living and man-made items. In contrast, phonology and grammar of spoken language were largely preserved, as was comprehension of complex syntactic commands. reading showed a pattern of surface dyslexia. Autobiographical and day-to-day (episodic) memory were relatively retained. Non-verbal memory, perceptual and visuospatial abilities were also strikingly preserved. In some cases, behavioural and personality changes may supervene; one patient developed features of the kluver-bucy syndrome. Radiological investigations have shown marked focal temporal atrophy in all five patients, and functional imaging by single positron emission tomography and positron emission tomography (one case) have implicated the dominant temporal lobe in all five. In the older literature, such cases would have been subsumed under the rubric of Pick's disease. Others have been included in series with progressive aphasia. We propose the term semantic dementia, first coined by Snowden et al. (1989), to designate this clinical syndrome.
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4/10. Abstract and concrete concepts have structurally different representational frameworks.

    The architecture supporting our conceptual knowledge of abstract words has remained almost entirely unexplored. By contrast, a vast neuropsychological, neurolinguistic and neuroimaging literature has addressed questions relating to the structure of the semantic system underpinning our knowledge of concrete items (e.g. artefacts and animals). In the context of semantic refractory access dysphasia, a series of experiments exploring and comparing abstract and concrete word comprehension are described. We demonstrate that semantically associated abstract words reliably interfere with one another significantly more than semantically synonymous abstract words, while concrete words show the reverse pattern. We report the first evidence that abstract and concrete word meanings are based in representational systems that have qualitatively different properties. More specifically, we show that abstract concepts, but not concrete concepts, are represented in an associative neural network. Furthermore, our patient was found to have significantly greater difficulty in identifying high frequency than low frequency abstract words. This observation constitutes the first evidence of an inverse word frequency effect. Our results challenge the generality of many existing models of human conceptual knowledge, which derive their structure from experimental findings in the concrete domain alone.
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keywords = animal
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5/10. Lexical organization of nouns and verbs in the brain.

    The analysis of neuropsychological disorders of lexical processing has provided important clues about the general organization of the lexical system and the internal structure of the processing components. Reports of patients with selective dysfunction of specific semantic categories such as abstract versus concrete words, living things versus inanimate objects, animals, fruits and vegetables, proper names and so forth, support the hypothesis that the neural organization of the semantic processing component is organized in these categories. There are reports of selective dysfunction of the grammatical categories noun and verb, suggesting that a dimension of lexical organization is the grammatical class of words. But the results reported in these studies have not provided unambiguous evidence concerning two fundamental questions about the nature and the locus of this organization within the lexical system. Is the noun-verb distinction represented in the semantic or in the phonological and orthographic lexicons? Is grammatical-class knowledge represented independently of lexical forms or is it represented separately and redundantly within each modality-specific lexicon? Here we report the performance of two brain-damaged subjects with modality-specific deficits restricted principally (H.W.) or virtually only (S.J.D) to verbs in oral and written production, respectively. The contrasting performance suggests that grammatical-class distinctions are redundantly represented in the phonological and orthographic output lexical components.
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keywords = animal
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6/10. Progressive language impairment without dementia: a case with isolated category specific semantic defect.

    A patient is described with a 5 year progressive defect of naming and auditory verbal comprehension, the pathological nature of which was presumably degenerative. The auditory comprehension defect unevenly affected different semantic categories, and was particularly severe for the names of animals, fruits and vegetables. The patients showed loss of the verbal knowledge of the physical attributes of the concepts corresponding to the words he was unable to understand, and sparing of the verbal knowledge of the functional attributes. His performance was defective also on the colour-figure and sound-picture matching test.
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keywords = animal
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7/10. Rejection behaviour: a human homologue of the abnormal behaviour of Denny-Brown and Chambers' monkey with bilateral parietal ablation.

    A unique behavioural syndrome in humans followed two separate strokes involving both parietotemporal regions. The behavioural alterations resemble those of Denny-Brown and Chambers' monkey with bilateral ablation of the parietal lobe which were characterised by strong withdrawal or refusal to be touched on the limbs and head. In both humans and animals, touch on the limbs or head elicited exaggerated withdrawal movements and refusal to be touched on the lips and tongue resulted in difficulty in feeding. These behavioural alterations can be interpreted as loss of exploratory activities towards extrapersonal space, or more positively, as rejection of contact with the environment. This rejection behaviour in which tactile, visual, and/or gustatory exploration tendencies are altered, is a counterpart of human frontal lobe syndrome and human kluver-bucy syndrome.
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keywords = animal
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8/10. anomia for animals in a child.

    The occurrence of anomia which particularly affected the category of animals is described in a 12-year-old boy. This difficulty cannot be accounted for by frequency or familiarity and is unaffected by whether the stimulus is a line drawing, photograph or model. The deficit does not represent development lag, as normal children of the same naming age differ qualitatively. The results, which include a one year follow-up, are discussed in relation to unitary versus multiple semantic systems. The disorder includes a disturbance of memory arising during the developmental period. It is suggested that items which are involved in daily actions can be more easily remembered than those which are identified by sensory features alone, and that the preserved learning of motor skills in acquired amnesia may be of relevance.
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ranking = 5
keywords = animal
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9/10. Category specific access dysphasia.

    In this study we report our investigations of the residual auditory-verbal comprehension skills of a global dysphasic who had sustained a major left hemisphere infarction. Clinically V.E.R.'s capacity for propositional speech and her comprehension of the simplest verbal instructions appeared to be absent. Nevertheless using matching-to-sample techniques it was possible to demonstrate the selective preservation (foods, animals and flowers) and the selective impairment (objects) of specific semantic categories. Furthermore there was evidence from analyses of response consistency and presentation rate effects that her deficit was primarily one of access to the full semantic representation of words. We suggest that this access impairment arose because the system had become refractory, such refractoriness being category specific.
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keywords = animal
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10/10. Towards a unitary account of access dysphasia: a single case study.

    We report the case of a patient, H.E.C., with a profound verbal comprehension impairment. His comprehension impairment involved both common names (animal and inanimate items) and proper names. Within the proper name category, his comprehension of country and famous peoples' names was better than his comprehension of common forenames. By using matching to sample techniques, H.E.C.'s impairment was found to be affected by presentation rate and by semantic relatedness, but not by word frequency. An analysis of his responses showed marked inconsistency and serial position effects (i.e. a decrement of performance on subsequent presentations of the same items). H.E.C.'s comprehension deficit was interpreted in terms of an "access" impairment within the word-meaning system. A unitary account of this impairment in terms of a deficit that delays the return, following activation, of the set of representations underlying a word, to a "ready state" is proposed.
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keywords = animal
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