Cases reported "Anomia"

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1/17. The impact of semantic memory impairment on spelling: evidence from semantic dementia.

    We assessed spelling and reading abilities in 14 patients with semantic dementia (with varying degrees of semantic impairment) and 24 matched controls, using spelling-to-dictation and single-word reading tests which manipulated regularity of the correspondences between spelling and sound, and word frequency. All of the patients exhibited spelling and reading deficits, except at the very earliest stages of disease. Longitudinal study of seven of the patients revealed further deterioration in spelling, reading, and semantic memory. The performance of both subject groups on both spelling and reading was affected by regularity and word frequency, but these effects were substantially larger for the patients. Spelling of words with exceptional (or more precisely, unpredictable) sound-to-spelling correspondences was most impaired, and the majority of errors were phonologically plausible renderings of the target words. reading of low frequency words with exceptional spelling-to-sound correspondences was also significantly impaired. The spelling and reading deficits were correlated with, and in our interpretation are attributed to, the semantic impairment.
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2/17. Implicit word cues facilitate impaired naming performance: evidence from a case of anomia.

    Word-finding difficulties observed in some patients with anomia have been attributed to an insufficient activation of phonology by semantics. There are, however, few direct tests of this hypothesis. This paper reports the case of FR, who presented with anomic aphasia following temporal lobe epilepsy and a cavernoma in the left superior temporal lobe. His anomic deficit was characterized by: (1) no apparent associated semantic impairment; (2) item consistency for accuracy and errors across different administrations; (3) accuracy strongly correlated with word frequency; and (4) a partial, albeit weak, knowledge of the gender of unnamed items. We conducted a naming experiment in which target pictures were implicitly primed by briefly presented masked words. Results showed that the prior presentation of the written target name improved accuracy. When compared with unprimed trials, the presence of the primes also increased phonological errors and decreased semantic errors. We argue that automatic phonological activation derived directly from the implicit written primes interacted with the remaining phonological input from the picture's semantic representation leading to increased accuracy and a change in the balance of error types.
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3/17. Relearning of verbal labels in semantic dementia.

    Semantic dementia is a degenerative disorder of temporal neocortex characterised by loss of word and object concepts. There is limited evidence that temporary relearning of lost vocabulary may be possible, attributed to sparing of hippocampal structures. However, learning is variable across patients and factors underlying learning success are poorly understood. The study investigated relearning of object names in two severely anomic semantic dementia patients. Following memory models that assume that hippocampal memories require some neocortical representation to underpin them it was predicted that relearning would be influenced by patients' residual semantic information about stimuli. Experiment 1 confirmed that residual knowledge influenced learning success. On the assumption that neocortical knowledge encompasses concepts of space and time, as well as words and objects, it was predicted that learning would be affected by the availability of contextual (temporo-spatial) information. Experiment 2 demonstrated effective learning of object names, attributed to the patient's use of temporal order and spatial position knowledge. Retention of object names over months was linked to the patient's capacity for autobiographical experiential (temporo-spatial contextual) association. The findings indicate that relearning of lost vocabulary is possible in semantic dementia, indicating a role of the medial temporal lobes in the acquisition of semantic information. Effective learning does not imply reinstatement of lost concepts, but, it is argued, does involve some reacquisition of meaning. The findings challenge the traditional semantic-episodic memory dichotomy and are consistent with a "levels of meaning" account of semantic memory.
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4/17. Questioning the living/nonliving dichotomy: evidence from a patient with an unusual semantic dissociation.

    In this article the authors describe a patient (J.P.) whose category-specific naming deficit eluded the classical dichotomies between living versus nonliving items or visual versus functional attributes. At age 22, he had herpes simplex encephalitis followed by a left temporal lobectomy. J.P. was tested on measures of visual perception, category naming, fluency, and name-picture matching. He showed a severe impairment naming and identifying fruits, vegetables, and musical instruments. His performance with animals and birds was spared inconsistently, meaning that even the preserved categories were, at some point, affected. J.P.'s unusual deficit supports the hypothesis that semantic knowledge is organized in the brain on the basis of object properties, which can cut across the living-nonliving categorical distinction.
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5/17. The role of context in remembering familar persons: insights from semantic dementia.

    Semantic dementia (SD) is a progressive condition characterized by an insidious and gradual breakdown in semantic knowledge. patients suffering from this condition gradually lose their knowledge of objects and their attributes, concepts, famous persons, and public events. In contrast, these patients maintain a striking preservation of autobiographical memory. The aim of the present study was to examine in a patient suffering from SD the role of context in the ability to recall knowledge of familiar persons. In an experiment, patient J.M. was asked to name and identify familiar persons that appeared on family photographs from recent and remote periods of her life. In the first experimental condition, the pictures represented personally familiar persons present in a specific spatial and temporal context. In a second experimental condition, the pictures showed personally familiar persons who were presented without any specific episodic context. Results indicate that the patient was able to name and identify familiar persons irrespective of the context of presentation (with/without context) and of the time period (recent/remote). No temporal gradient was found using family photographs. Finally, in contrast with familiar persons, J.M. presented a severe anomia for celebrities. Results are discussed in light of recent research in the field.
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6/17. Modality-specific naming deficit: cognitive and neural mechanisms implicated in naming to definition.

    We report the case of an anomic patient who had a significantly greater impairment in naming to definition than in picture naming. His difficulty did not depend on the number of semantic attributes (two vs. four) or type of information (visual vs. non-visual) carried in the definition. When asked to visualize the perceptual characteristics of the stimulus by means of drawing, his performance on the naming to definition task improved significantly. We first discuss this performance pattern in terms of the debate between the modality access deficit hypothesis and the multiple semantics position. The patient's more severe impairment in naming to definition suggests that his dissociation may be due to a more selective involvement of verbal semantics. In line with recent PET findings indicating that top-down semantic-to-visual sensory neural feedback improves the retrieval of semantic information in naming to definition tasks, we hypothesize that the patient's difficulty in retrieving the name was due to his inability to automatically activate this pathway. Picture drawing facilitated his naming because it activated the visual system directly (through the structure description level), implementing the retrieval of semantic information.
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7/17. Preservation of propositional speech in a pure anomic: the importance of an abstract vocabulary.

    We describe a detailed quantitative analysis of the propositional speech of a patient, FAV, who became severely anomic following a left occipito-temporal infarction. FAV showed a selective noun retrieval deficit in naming to confrontation and from verbal description. Nonetheless, his propositional speech was fluent and content-rich. To quantify this observation, three picture description-based tasks were designed to elicit spontaneous speech. These were pictures of professional occupations, real world scenes and stylised object scenes. FAV's performance was compared and contrasted with that of 5 age- and sex-matched control subjects on a number of variables including speech production rate, volume of output, pause frequency and duration, word frequency, word concreteness and diversity of vocabulary used. FAV's propositional speech fell within the range of normal control performance on the majority of measurements of quality, quantity and fluency. Only in the narrative tasks which relied more heavily upon a concrete vocabulary, did FAV become less voluble and resort to summarising the scenes in an manner. This dissociation between virtually intact propositional speech and a severe naming deficit represents the purest case of anomia currently on record. We attribute this dissociation in part to the preservation of his ability to retrieve his abstract word vocabulary. Our account demonstrates that poor performance on standard naming tasks may be indicative of only a narrowly defined word retrieval deficit. However, we also propose the existence of a feedback circuit which guides sentence construction by providing information regarding lexical availability.
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8/17. Progressive loss of access to spoken word forms in a case of Alzheimer's disease.

    We report the results of a longitudinal study of a progressive anomia in a patient with dementia of the Alzheimer type (DAT). The anomia cannot be attributed to a deficit within the semantic system, but appears instead to arise from impaired access to the phonological lexicon at a post-semantic stage of the naming process: a deficit that hitherto has not been reported in DAT. Specific naming responses were affected consistently by the disorder, showing that disorders of access are not invariably associated with inconsistent responding. Before specific responses disappeared from spontaneous use, there appeared to be an intervening stage at which some responses could be elicited by an initial phoneme cue, suggesting a low level of spontaneous activity of insufficient strength to elicit a response unaided. The frequency of the name affected naming performance, but did not appear to interact with the severity of the naming disorder, suggesting that the parameters of the normal naming system were unaffected. It is claimed that important new insights into the characteristics of progressive anomia have been obtained by taking a longitudinal approach.
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9/17. Two systems for colour-naming defects: verbal disconnection vs colour imagery disorder.

    Two subjects affected by pure alexia and showing no central dyschromatopsia or generalized aphasia, performed poorly on traditional tasks with visually-presented colour stimuli and on tasks with objects presented verbally. Three experiments were conducted to evaluate the possible role of mental colour imagery in recalling the colours of objects from memory. It was concluded that Case I, with left occipital lobe softening, had preserved imagery systems, but failed to recode the colours of mentally generated colour images, just as he failed to name visually presented colours, suggesting a language-imagery disconnection. In contrast, Case II, with a bilateral occipital lesion, had sustained damage to her long-term visual memories for colours as chromatic attributes of objects. This content-specific imagery deficit was concomitant with colour agnosia. The present findings are discussed in terms of current cognitive theories on imagery deficits.
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10/17. Lexical morphology and its role in the writing process: evidence from a case of acquired dysgraphia.

    A case of acquired dysgraphia is presented in which the deficit is attributed to an impairment at the level of the Graphemic Output Buffer. It is argued that this patient's performance can be used to identify the representational character of the processing units that are stored in the Orthographic Output Lexicon. In particular, it is argued that the distribution of spelling errors and the types of lexical items which affect error rates indicate that the lexical representations passed from the lexical output system to the Graphemic Output Buffer correspond to the productive morphemes of the language.
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