11/44. Deep dysphasia: analysis of a rare form of repetition disorder."Deep dysphasia" is the parallel in repetition to the reading impairment deep dyslexia. Our patient, S.M., showed part of speech, word/nonword, and concreteness effects in repetition, and he made semantic errors, but his oral reading was relatively spared. Further testing indicated that S.M. did not have difficulty perceiving spoken stimuli or deciding their lexical status, but he was deficient at semantically processing spoken words. Moreover, his phonemic memory was severely impaired. We argue that the routes for repetition (lexical and nonlexical) that function without semantic mediation were defective and that deficits in phonemic memory further diminished their effectiveness, since initial phonological encoding of spoken words was not available to guide the output stages of phonological processing. In addition, the semantically mediated route for repetition was unreliable because semantic processing was faulty and S.M. could not accurately label concepts.- - - - - - - - - - ranking = 1keywords = speech (Clic here for more details about this article) |
12/44. Troubled letters but not numbers. Domain specific cognitive impairments following focal damage in frontal cortex.A well educated right-handed woman developed severe and stable alexia and agraphia following a circumscribed surgical lesion in the left premotor cortex. The lesion was located in Brodmann's field 6, above Broca's area, in the region traditionally referred to as Exner's area. The alexia and agraphia occurred in a pure form, that is, in the setting of otherwise normal cognitive and neurological function. She was not aphasic or hemiparetic and her visual perception, intellect, memory, oral spelling and drawing were normal. The patterns of impairment of reading and writing closely paralleled one another. reading of single words and letters was severely impaired, and she was entirely unable to read sentences. She was virtually unable to write recognizable letters, could write no words, and her writing attempts were severely distorted spatially. By contrast, she could easily read all numbers and nonverbal symbols, and she was equally able to write numbers and perform written calculations without difficulty. These striking dissociations provide further evidence of the domain specificity of cognitive/neural representations. They also point to the possible role of premotor cortices in the coactivation of precise sequences of motor and sensory activity patterns involved in reading and writing.- - - - - - - - - - ranking = 2.4117335151023keywords = perception (Clic here for more details about this article) |
13/44. Direct dyslexia. Preserved oral reading of real words in Wernicke's aphasia.A 70-yr-old man was able to read aloud, without comprehending what he read, following a stroke that caused Wernicke's aphasia with severely impaired comprehension of speech. Tested on admission, and at 3 and 9 months, he could read aloud both orthographically simple and orthographically complex real words, and showed neither semantic errors, preference for nouns, nor difficulty with function words. He could not, however, read aloud orthographically simple nonwords. His disorder thus appears to be the first pure example of 'direct dyslexia', which, in contrast to previously well-documented examples of 'deep' and 'surface' dyslexia, implies the existence in reading of a direct route, independent of phonology or semantics, between visual and oral word representations.- - - - - - - - - - ranking = 1keywords = speech (Clic here for more details about this article) |
14/44. prosopagnosia: a defect in visual configural processing.A patient with severe, lasting prosopagnosia could not get an immediate overview of a face sufficiently specific for successful identification. He also failed completely in tasks of visual closure despite adequate performances on numerous other tests of visual perception and memory. We conclude that prosopagnosia represents a loss of visual "configural processing"--a learned skill enabling immediate identification of individual members of a class without conscious visuospatial analysis or remembering. prosopagnosia and agnosic alexia represent two distinct defects of configural processing: Alexics cannot identify items with distinctive features that are themselves identifiable. Prosopagnosics cannot identify objects whose critical distinguishing features have no independent identities.- - - - - - - - - - ranking = 2.4117335151023keywords = perception (Clic here for more details about this article) |
15/44. Positional dyslexia.Position-specific errors in word reading are usually associated with neglect or visual extinction on the same side as the reading problem. In this study, two patients with left-hemisphere lesions showed visual extinction on the right but reading difficulty on the left side of words and pseudowords. Further study of one patient revealed that he also had problems reading the beginning of words presented tachistoscopically or in vertical orientation. In addition, the positional difficulty was apparent when he named the letters in words. The pattern of results indicates that the positional dyslexia in these patients was not likely attributable to general deficits in visual perception or attention but may have reflected a disorder at a later stage of letter processing.- - - - - - - - - - ranking = 2.4117335151023keywords = perception (Clic here for more details about this article) |
16/44. Visual processes in a hemialexic patient with posterior callosal section.A patient with surgical section of the splenium and, probably, the posterior end of the truncus of the corpus callosum was studied 9-13 yr after the operation. His reading aloud, reading comprehension and word-matching abilities were moderately disturbed only in the left hemifield. These three disturbances were equally disturbed. The disturbances were not the result of visual disturbances such as tachistoscopic hemiamblyopia or tachistoscopic hemineglect since Landolt's ring matching was intact in the left hemifield as well as in the right. The disturbances were also not due to the disturbance of tachistoscopic word perception since the patient correctly performed same-different judgment of pairs of words in each hemifield. In his reading aloud and reading comprehension disturbances, ideogram words were less impaired than phonogram words, even when the number of letters in the words was the same. His picture naming ability was not disturbed in each hemifield.- - - - - - - - - - ranking = 2.4117335151023keywords = perception (Clic here for more details about this article) |
17/44. Transcortical sensory aphasia: evidence for subtypes.Impaired auditory comprehension and fluent but semantically empty speech in conjunction with preserved repetition characterize the syndrome of transcortical sensory aphasia (TSA). Repetition, however, may be mediated by at least two distinct processes--a lexical process that may involve the recognition and subsequent activation of discrete stored word representations and a nonlexical process that involves phonologic decoding and immediate phonologic encoding from immediate memory. We investigated the spontaneous speech, reading, and tendency to recognize and spontaneously correct syntactic errors in four patients with TSA: this analysis suggests there are two subtypes of TSA. We contend that in one subtype both the lexical and direct repetition (or speech production) mechanisms are preserved, but in the second subtype the lexical mechanism is disrupted and repetition is mediated by the nonlexical mechanism.- - - - - - - - - - ranking = 3keywords = speech (Clic here for more details about this article) |
18/44. Left hemisphere pathways in reading: inferences from pure alexia without hemianopia.In pure alexia, reading is impaired despite almost normal speech, spelling, and writing. We studied a right-handed man with pure alexia, but no hemianopia. He had more difficulty reading longer words (word-length effect), but had no selective reading impairment in phonologic or semantic analysis. Clinical-CT correlation suggests that (1) left hemisphere visual pathways crucial for reading arise from or pass close to the left occipitotemporal or inferior temporal gyrus, and (2) relevant transcallosal fibers from the right hemisphere course inferior to the posterior horn of the left lateral ventricle before ascending to left hemisphere language areas.- - - - - - - - - - ranking = 1keywords = speech (Clic here for more details about this article) |
19/44. Wernicke's and global aphasia without alexia.It has been proposed that the comprehension of written language requires transcoding from the visual (grapheme) to the auditory (phoneme). It has also been proposed that visual word images can be comprehended without grapheme-phoneme transcoding. We describe three aphasic patients with left hemisphere impairment who had poor speech comprehension but could comprehend written language. One of these patients had a subsequent right hemisphere lesion and lost his ability to read. We propose that the right hemisphere in some individuals may be capable of extracting semantic information from iconic images (ideogram) without phonological processing.- - - - - - - - - - ranking = 1keywords = speech (Clic here for more details about this article) |
20/44. Alexia without agraphia in a musician after transcallosal removal of a left intraventricular meningioma.After a meningioma situated in the trigone of the left lateral ventricle was excised by the transcallosal approach of Kempe and Blaylock, a right-handed musician with a right hemianopsia developed alexia without agraphia. In contrast to previously reported cases of this syndrome arising from other etiologies, he was unable to read single letters or numbers. Neuropsychological studies at 42 and 126 days after operation also disclosed an inability to associate auditory or tactile stimuli with visually perceived material, whereas speech and verbal comprehension were intact. Although the alexia extended to musical notes, he could interpret other musical symbols (e.g., treble clef). Appreciation of rhythm and expressive musical ability were relatively preserved, although judgment of other musical features (including discrimination of pitch, duration, and loudness) was compromised. The findings suggest that alexia may occur as a consequence of the transcallosal procedure when a right hemianopsia is present. However, other linguistic abilities may be better preserved by the transcallosal approach to the ventricle than by a transcortical operation.- - - - - - - - - - ranking = 8.8123049125667keywords = discrimination, speech (Clic here for more details about this article) |
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