1/44. Alexia for Braille following bilateral occipital stroke in an early blind woman.Recent functional imaging and neurophysiologic studies indicate that the occipital cortex may play a role in Braille reading in congenitally and early blind subjects. We report on a woman blind from birth who sustained bilateral occipital damage following an ischemic stroke. Prior to the stroke, the patient was a proficient Braille reader. Following the stroke, she was no longer able to read Braille yet her somatosensory perception appeared otherwise to be unchanged. This case supports the emerging evidence for the recruitment of striate and prestriate cortex for Braille reading in early blind subjects.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
2/44. Intensive training of phonological skills in progressive aphasia: a model of brain plasticity in neurodegenerative disease.Three patients with a typical syndrome of nonfluent primary progressive aphasia (Mesulam's syndrome) were trained daily with a remediation protocol including auditory exercises specifically designed to involve several aspects of phonological processing, a domain known to be specifically affected in the condition. The speech content of the exercises was based on the temporal theory of phonological processes according to which increasing the duration of formant transition should facilitate phoneme discrimination and phoneomic awareness. Significantly improved performance on the trained tasks was demonstrated in the three patients. Improvement further generalized to other tasks such as nonword repetition and reading. We conclude that such results (1) argue for using intensive focused therapy of language impairment in neurodegenerative disorders, (2) may constitute a good model of brain plasticity in neurodegenerative disorders in general, and (3) support theories of phonological processing emphasizing temporal features of the auditory signal.- - - - - - - - - - ranking = 3.6539297801286keywords = discrimination, speech (Clic here for more details about this article) |
3/44. Clinical and neuroradiological findings in a case of pure word deafness.Pure Word deafness is a clinical syndrome included among the aphasias and is marked by complete deafness of sudden onset with conserved ability to understand and read the written word and with no speech disorders. We report the case of 61 year old man in whom pure word deafness developed after two episodes of acute cerebral ischemia in quick succession. neuroimaging procedures, that is: computed tomography scan, single photon emission computed tomography and magnetic resonance imaging, revealed the presence of two ischemic lesions in the temporal cortex bilaterally. Neurophysiological investigations (electroencephalogram, brainstem auditory evoked potentials and stapedial reflex) were also studied. We discuss the outcome of all these investigations in the light of the relevant published work.- - - - - - - - - - ranking = 0.41463950877573keywords = speech (Clic here for more details about this article) |
4/44. Visual word recognition in the left and right hemispheres: anatomical and functional correlates of peripheral alexias.According to a simple anatomical and functional model of word reading, letters displayed in one hemifield are first analysed through a cascade of contralateral retinotopic areas, which compute increasingly abstract representations. Eventually, an invariant representation of letter identities is created in the visual word form area (VWFA), reproducibly located within the left occipito-temporal sulcus. The VWFA then projects to structures involved in phonological or lexico-semantic processing. This model yields detailed predictions on the reading impairments that may follow left occipitotemporal lesions. Those predictions were confronted to behavioural, anatomical and functional MRI data gathered in normals and in patients suffering from left posterior cerebral artery infarcts. In normal subjects, alphabetic stimuli activated both the VWFA and the right-hemispheric symmetrical region (R-VWFA) relative to fixation, but only the VWFA showed a preference for alphabetic strings over simple chequerboards. The comparison of normalized brain lesions with reading-induced activations showed that the critical lesion site for the classical syndrome of pure alexia can be tightly localized to the VWFA. reading impairments resulting from deafferentation of an intact VWFA from right- or left-hemispheric input were dissected using the same methods, shedding light on the connectivity of the VWFA. Finally, the putative role of right-hemispheric processing in the letter-by-letter reading strategy was clarified. In a letter-by-letter reader, the R-VWFA assumed some of the functional properties normally specific to the VWFA. These data corroborate our initial model of normal word perception and underline that an alternative right-hemispheric pathway can underlie functional recovery from alexia.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
5/44. reading aloud in jargonaphasia: an unusual dissociation in speech output.A patient is described who showed several dissociations between oral and written language processing after bilateral retrorolandic vascular lesion. Dissociation was firstly between abolished auditory comprehension and preserved written comprehension and then involved confrontation naming, clearly superior in the written modality. The third striking dissociation involved oral output; spontaneous speech, although fluent and well articulated, consisted of neologistic jargon, while reading aloud was clearly superior though not perfect. Data are discussed with reference to a cognitive model of word processing. The pattern of dissociation in word production may be due to a failure in retrieving the phonological word form from the semantic system.- - - - - - - - - - ranking = 2.0731975438786keywords = speech (Clic here for more details about this article) |
6/44. Alexia and quadrant-amblyopia: reading disability after a minor visual field deficit.reading difficulties caused by hemianopia are well described. We present a study of alexia in a patient (NT) with a milder visual field deficit. The patient had suffered a cerebral haemorrhage causing damage to the left occipital cortex and underlying white matter. NT's text reading was slow and prone to error, but recognition of single letters was preserved. Single word reading was accurate, but slower than normal. On perimetric testing NT initially showed an upper right quadrantanopia, but by attending covertly to this quadrant he could achieve luminance detection except in a small scotoma above the reading line. A whole report experiment showed that letter perception was severely compromised in the quadrant, consistent with cerebral amblyopia. On follow-up testing one and a half year post stroke, a clear spontaneous recovery had occurred, reflected in improved text reading with close to normal eye movements. Still, subtle reading difficulties and oculo-motor abnormalities remained. overall, the study shows how amblyopia in one quadrant can lead to a characteristic form of alexia.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
7/44. Musical alexia with recovery: a personal account.I describe the experience of an acute loss of ability to read music and play the piano accurately and expressively following an embolic infarct of the right angular and supramarginal gyri in a setting of chronic migraine. Other parietal deficits included a small visual field defect, visual hallucinations, prosopagnosia, topographical disorientation, disturbance of perception of velocity of moving objects and dyscalculia. Recovery began within a month of the ictus after instituting a regular practice routine. The ability to read and play polyphony recovered before the ability to read homophonic music. A substantial degree of recovery of musical function occurred within 6 months and of the other parietal deficits over a year. Failure to maintain regular practice led to marked though recoverable deterioration. An increased frequency of migraine persisted for some 18 months.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
8/44. Neuropsychological studies of auditory-visual fusion illusions. Four case studies and their implications.A heard speech sound which is not the same as the synchronized speech sound can sometimes give rise to an illusory phonological percept. Typically, a heard /ba/ combines with a seen /ga/ to give the impression that /da/ has been heard (McGurk, H. and MacDonald, J. nature Lond. 264, 746-748, 1976). We report the susceptibility to this illusion of four individuals with localized brain lesions affecting perceptual function. We compare their performance to that of ten control subjects and relate these findings to the efficiency of processing seen and heard speech in separate and combined modalities. The pattern of performance strongly suggests LH specialization for the phonological integration of seen and heard speech. The putative site of such integration can be effectively isolated from unilateral and from bilateral inputs and may be driven by either modality.- - - - - - - - - - ranking = 1.6585580351029keywords = speech (Clic here for more details about this article) |
9/44. writing with the right hemisphere.We studied writing abilities in a strongly right-handed man following a massive stroke that resulted in virtually complete destruction of the language-dominant left hemisphere. writing was characterized by sensitivity to lexical-semantic variables (i.e., word frequency, imageability, and part of speech), semantic errors in writing to dictation and written naming, total inability to use the nonlexical phonological spelling route, and agrammatism in spontaneous writing. The reliance on a lexical-semantic strategy in spelling, semantic errors, and impaired phonology and syntax were all highly consistent with the general characteristics of right hemisphere language, as revealed by studies of split-brain patients and adults with dominant hemispherectomy. In addition, this pattern of writing closely resembled the syndrome of deep agraphia. These observations provide strong support for the hypothesis that deep agraphia reflects right hemisphere writing.- - - - - - - - - - ranking = 0.41463950877573keywords = speech (Clic here for more details about this article) |
10/44. Impaired phonological reading in primary degenerative dementia.This case study reports the profile of preserved and impaired capacities in a left-handed patient suffering from primary degenerative dementia of unknown aetiology. She was remarkable because her relatively preserved object naming and semantic categorization abilities contrasted with severe deficits in speech fluency, oral reading, inability to execute spoken and written commands, and severely impaired auditory-verbal short-term memory. Her reading disorder could be characterized as a disturbance of assembled phonology. She had great difficulty reading pronounceable nonwords, but she could correctly read irregular words. She showed effects of word imageability or concreteness (more than word frequency). She also showed effects of part-of-speech, where nouns and adjectives were read more easily than inflected verbs. She had difficulty reading function words. The syntactic category effects could be proven (by hierarchical log-linear analysis) not to be an artefact of imageability differences between verbs, adjectives and nouns. In reading aloud she made visual and morphological errors, but no semantic errors. This interesting pattern of preserved semantic information and disrupted phonological processing is unusual in dementia and contrasts with the severe dysnomia of patients with surface dyslexia who are able to read by the indirect, assembly-of-phonology route and show better reading of nonwords than irregular words. Her reading by a direct visual-semantic route appeared to be associated with relatively intact object naming, concrete word reading, and irregular word reading. This selective impairment of phonological reading in the context of partly preserved semantic abilities was interpreted as confirmation of the dissociability of language functions in primary degenerative dementia.- - - - - - - - - - ranking = 0.82927901755146keywords = speech (Clic here for more details about this article) |
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