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We report a quantitative investigation of the visual identification and auditory comprehension deficits of 4 patients who had made a partial recovery from herpes simplex encephalitis. Clinical observations had suggested the selective impairment and selective preservation of certain categories of visual stimuli. In all 4 patients a significant discrepancy(More)
The selective impairment of semantic memory is described in three patients with diffuse cerebrallesions. Thesepatients, selected on the basis of a failure to recognize or identify common objects (agnosia for objects), were investigated in detail. In particular, their perceptual, language and memory functions were assessed, and the limits and properties of(More)
In this study we investigated the category specificity of the comprehension impairments of Y.O.T., a patient with a severe global dysphasia. Using matching to sample techniques it was possible to demonstrate selective impairments and selective preservations not only of broad categories of semantic knowledge but also of particular subsets of such categories.(More)
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(More)
In this study we have reported our investigation of two patients with an acquired dyslexia characterized by letter-by-letter reading, whole word reading being apparently impossible. It has been shown that this phenomenon of letter-by-letter reading cannot be accounted for by visual or perceptual factors nor by impairment of visual span of apprehension. The(More)
In this paper we describe the construction of a Graded Difficulty Arithmetic test (GDA) consisting of 12 additions and 12 subtractions which are orally presented. The test was administered to a control group of 100 volunteer subjects with extra-cerebral neurological disorders and to two experimental groups of patients with unilateral cerebral lesions of the(More)
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Patients with cerebral lesions offer a unique opportunity to investigate the organization of meaning systems in the brain. Clinical neurologists have long been aware that knowledge of particular classes or categories of information may be selectively impaired in some cases and selectively spared in others. For example knowledge of letters, colours, objects,(More)
The hippocampal formation (HF) is known from pathological and MRI studies to be severely atrophied in established Alzheimer's disease. However, it is unclear when the earliest changes in the HF occur. We performed a longitudinal study of asymptomatic individuals at risk of autosomal dominant familial Alzheimer's disease in order to assess presymptomatic(More)