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PubMed1994

Impaired picture recognition with preserved object naming and reading.

A case study is reported on a left posterior cerebrovascular accident involving the infracalcarine cortex. The patient (HG) exhibited a marked color anomia and picture naming deficit (photograph anomia) without alexia. However, objects were named successfully from either visual or tactile inspection. Despite successful object categorization in several tasks, it is argued that HG's picture naming deficit is dependent on a disorder of recognition (access to the stored structural descriptions for objects). A similar functional impairment can account for HG's impaired color naming. The site of HG's cortical damage implies that recognition disorders can result from a unilateral left-sided lesion.

Aged↗
PubMed1997

Semantic, phonological, and perceptual changes following left and right intracarotid injection (Wada) with a low amytal dosage.

Intracarotid injection of a low dosage of amobarbital (75 mg, 5% solution) was studied in 30 temporal lobectomy candidates while naming achromatic, incongruously, and congruously colored pictorial objects and reading real, nonsense, and embedded words. Semantic errors and phonological alexia followed the left injection, while the right injection induced visuoperceptual errors. When the contralateral hemisphere was anesthetized, the left brain formulated supraordinate categories for words and objects, while the right brain applied concrete labels. The basic language proficiency of patients influenced recovery and outcome; left temporal patients who were interictally anomic performed especially poorly after both injections. Codifying phonological and perceptual changes during the intracarotid amobarbital procedure can improve interpretations about language laterality and organization.

Adult↗
PubMed1994

Reading with the right hemisphere: evidence from transcranial magnetic stimulation.

Although many patients with dominant hemisphere damage retain some reading ability, the anatomic substrate of the preserved reading remains controversial. We tested the hypothesis that the right hemisphere mediates the reading of some patients with acquired dyslexia by using Transcranial Magnetic Stimulation (TMS) to assess the effect of transient cortical stimulation on reading. A patient with (partially recovered) pure alexia was asked to read aloud briefly presented words, half of which were shown in association with TMS of the right or left hemisphere. Consistent with the right hemisphere reading hypothesis, stimulation of the right but not the left hemisphere disrupted oral reading.

Cerebral Infarction↗
PubMed1996

Deep dyslexic phenomena in a letter-by-letter reader.

Numerous accounts of pure alexia have suggested that prelexical impairment precludes rapid access to orthographic information in patients with the disorder. We report a patient with features of both pure and partially recovered deep dyslexia in whom we demonstrate prelexical deficits in maintaining a reliable abstract representation of the right side of letter arrays, as well as in modulating a "spotlight" of visual attention. These deficits, we suggest, encourage the patients's use of a letter-by-letter reading strategy; despite them, however, he demonstrates rapid, accurate reading of some, but not all classes of words. Furthermore, the patient's reading is influenced by both prelexical and lexical-semantic factors such that speed and accuracy are optimal for high imagiability nouns of few letters. Finally, the patient accurately names orally spelled words of all classes. Taken together, these data are consistent with the hypothesis that rapid reading may be enabled by lexical-semantic support from a right hemisphere-mediated processing system which recognizes words as whole, thereby mitigating the effect of the prelexical deficits.

Brain Ischemia↗
PubMed1999

A functional lesion in developmental dyslexia: left angular gyral blood flow predicts severity.

Functional imaging studies have shown reduced regional cerebral blood flow (rCBF) in temporal and inferior parietal regions in dyslexia. To relate such abnormalities to the severity of dyslexia, correlations between reading skill and rCBF during a series of reading tasks and visual fixation were mapped for 17 right-handed dyslexic men, ages 18-40, and 14 matched controls. These correlations uniquely identified the left angular gyrus as the most probable site of a functional lesion in dyslexia: Here, higher rCBF was associated with better reading skill in controls (p <.01), but with worse reading skill in dyslexia (p <.01). This suggests that greater reliance on this region normally facilitates reading, but impairs reading in dyslexia. Thus, developmental dyslexia may share a common localization with alexia.

Adolescent↗
PubMed2000

Selective uppercase dysgraphia with loss of visual imagery of letter forms: a window on the organization of graphomotor patterns.

We report a patient who, after a left parieto-occipital lesion, showed alexia and selective dysgraphia for uppercase letters. He showed preserved oral spelling, associated with handwriting impairment in all written production; spontaneous writing, writing to dictation, real words, pseudowords, and single letters were affected. The great majority of errors were well-formed letter substitutions: most of them were located on the first position of each word, which the patient always wrote in uppercase (as he used to do before his illness). The patient also showed a complete inability to access the visual representation of letters. As demonstrated by a stroke segmentation analysis, letter substitutions followed a rule of graphomotor similarity. We propose that the patient's impairment was at the stage where selection of the specific graphomotor pattern for each letter is made and that the apparent selective disruption of capital case was due to a greater stroke similarity among letters belonging to the same case. We conclude that a visual format is necessary neither for spelling nor for handwriting.

Aged↗
PubMed2001

Does dyslexia develop from learning the alphabet in the wrong hemisphere? A cognitive neuroscience analysis.

A new perspective is described which views developmental dyslexia as the outcome of learning to write the alphabet in the nondominant (right) hemisphere. The letter-level and whole-word subtypes of dyslexia are seen as differing responses adopted to cope with this predicament. Striking similarities between dyslexics and callosotomy patients in the allocation of covert attention to lateralized stimuli provide direction for integrating a diversity of dyslexic research within this framework. This synthesis, together with information from pure alexia, brain activation, and reading research, lends insight into the neural circuitry of the compensatory strategies adopted by the two dyslexic subtypes.

Brain↗
PubMed1990

Neuropsychological evaluation and rehabilitation in mental retardation.

A discussion is provided of issues related to neuropsychological assessment of mentally retarded individuals. The first matters considered are test selection in relation to mental age and diagnostic issues. Various methods of evaluation are then considered, including assessment of orientation to sound and visual stimuli, language comprehension, right-left discrimination, and abstract and symbolic processes. Methods are also reviewed for detailed evaluation of language functions including testing for aphasia and for academic skills such as reading, writing, and calculation, as well as for spatial and constructional abilities. A section is devoted to use of neuropsychological assessment for rehabilitation of various disorders such as congenital aphasia, alexia, and spatial-constructional disorders.

Brain Damage, Chronic↗
PubMed1994

One hundred years of neuropsychology in Japan: retrospect and prospect.

The development of neuropsychology in Japan since the end of the 19th century will be outlined, including a number of pioneering works that gave a scientific basis to contemporary Japanese neuropsychology. The activities of societies/associations of related disciplines as well as the educational systems of clinical and experimental neuropsychology, which represents in Japan an interdisciplinary field, will be described. After national and international activities are mentioned, a review of significant Japanese contributions to main topics in neuropsychology will be given in some detail: dementia, memory disorders, frontal lobe syndromes, aphasia-alexia-agraphia, callosal syndromes, and specific right hemisphere syndromes. The issues of these interdisciplinary scientific investigations have found application in language and cognitive disabilities of brain-damaged patients, as well as evaluation of medical treatments and comedical rehabilitational effects, care, and counseling. Finally, some comments will be presented on possible and desirable developments of Japanese neuropsychology in the future.

History, 19th Century↗
PubMed2001

Hyperacute cognitive stroke syndromes.

Cognitive syndromes are common clinical manifestations of hyperacute stroke and may be the single or dominant presenting features. They are related to acute dysfunction of complex integrated distributed functional networks serving different cognitive domains. The most common cortical syndromes include nonfluent or fluent aphasia, neglect, collor agnosia, pure alexia and Balint's syndrome. Disturbances of declarative memory are common following posterior cerebral artery and thalamic strokes. Abulia can follow thalamic, caudate and capsular lesions. Intraventricular and subarachnoid haemorrhages can cause preeminent neuropsychological changes. Disorientation is present in about 40% of acute stroke patients and delirium complicates the course of 25% of acute strokes. Some hyperacute cognitive stroke syndromes are useful indicators of later disability. Cognitive syndromes may pose special difficulties to neurology residents, unless formal teaching in neuropsychology and psychiatry is included in their training programs.

Acute Disease↗
PubMed2004

[Early recognition of speech and speech-associated disorders after acute stroke].

In the course of increasing demands in acute stroke care in stroke units, criteria for efficient speech diagnosis, which can be applied in the first hours of acute stroke are necessary. In this study we investigated early recognition of speech and speech-associated disorders in acute stroke, and compared the neurologists' clinical diagnoses at admission with the results of a test battery (KAP--Kurze Aphasieprüfung). 90 of 104 consecutively recruited patients could be tested within the first three days. 53.8% (n = 49/N = 91) of the patients presented with language disorders in the clinical neurological examination at admission compared to 63.7% (n = 58/N = 91) that were found to have language disorders according to KAP. Syndrome classification in the group of aphasias showed a frequent occurrence of global aphasia, unclassified aphasia, anomic aphasia and agraphia. Speech apraxia and alexia were always accompanied by aphasia. A large amount of patients are affected by a variety of speech disorders. This study could show that a portion of these disorders could not be diagnosed in the acute situation without using a standardized test battery. Therefore clinical examination should be supplemented by standardized tests in routine diagnosis of speech disorders in acute stroke units in order to treat every patient adequately as soon as possible.

Acute Disease↗
PubMed2006

Posterior cortical atrophy: a brief review.

Posterior cortical atrophy is a striking clinical syndrome in which a dementing illness begins with visual symptoms. Initially, the problem may seem to be loss of elementary vision, but over time the patient develops features of visual agnosia, topographical difficulty, optic ataxia, simultanagnosia, ocular apraxia (Balint's syndrome), alexia, acalculia, right-left confusion, and agraphia (Gerstmann's syndrome), and later a more generalized dementia. Occasional patients have visual hallucinations and signs of Parkinson's disease or Lewy body dementia. A number of different neuropathologic disorders are associated with posterior cortical atrophy.

Atrophy↗
PubMed1982

The possible existence of phonemic reading in the presence of Broca's aphasia: a case report.

This case study examined phonemic reading and reading comprehension in the presence of Broca's aphasia. The patient, T.B., a 16 yr old male, suffered an occlusion of the middle cerebral artery. Spontaneous speech was limited, naming difficulties were apparent, and comprehension was mildly impaired. Though the patient could read only a small number of words aloud, he was able to read silently for comprehension on a standardized instrument. Moreover, T.B. was able to match orally-presented pseudowords to their written analogs, a finding which suggests that phonemic processing for nonlexical material was to some degree intact. The results were contrasted to the reading patterns usually reported to be present in "frontal" alexia and deep dyslexia. The possible existence of a dissociation between phonemic processing in reading and speech behavior as well as its mechanism was discussed.

Adolescent↗
PubMed1991

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.

Aged↗
PubMed1992

Reversed laterality of cerebral functions in a non-right-hander: neuropsychological and spect findings in a case of 'atypical' dominance.

A 54-year-old non-right-handed man with positive familial sinistrality showed a pure right hemisphere syndrome following a left hemisphere stroke. Severe right side hemineglect, transcortical motor dysprosodia, spatial dysgraphia and visuo-constructive impairments were observed. At no time were the expected left hemisphere abnormalities such as aphasia, alexia, right-left disorientation or finger agnosia noted. A left fronto-temporal subcortical lesion was documented on CT scan. A Tc-99m HM-PAO SPECT study revealed no cerebral blood flow changes in the right hemisphere while in the left hemisphere a fronto-temporo-parietal cerebral blood flow reduction was evident. This case of a complete reversed laterality of cognitive functions argues for a distinction to be made between 'anomalous' cerebral dominance and 'atypical' cerebral dominance.

Brain↗
PubMed1995

A case of 'sign blindness' following left occipital damage in a deaf signer.

We report on a right-handed, deaf, life long signer who suffered a left posterior cerebral artery (PCA) stroke. The patient presented with right homonymous hemianopia, alexia and a severe sign comprehension deficit. Her production of sign language was, however, virtually normal. We suggest that her syndrome can be characterized as a case of 'sign blindness', a disconnection of the intact right hemisphere visual areas from intact left hemisphere language areas. This case provides strong evidence that the neural systems supporting sign language processing are predominantly in the left hemisphere, but also suggests that there are some differences in the neural organization of signed vs spoken language within the left hemisphere.

Female↗
PubMed1994

Dissociation of local and global processing in visual agnosia.

Subsequent to strokes in the right and left inferomedial occipito-temporal lobes, two patients became prosopagnosic and alexic, respectively. They also show a complementary dissociation of the analysis of handwritten text. The patient with the right posterior stroke can read it but not recognize whose handwriting it is; the patient with the left posterior stroke cannot read the text but knows who wrote it. The analysis of spatial vision revealed that the prosopagnosic patient has no problem with seeing texture elements when presented in isolation. Yet she performs poorly with Moiré and texture perception, i.e. she suffers from a selective loss of global visual perception. The alexic patient performs well with Moiré patterns but neither with (complex) texture elements nor with textures. She seemingly can locally and globally process patterns composed of simple figural elements but fails with stimuli that require the integration of features. This finding of a concomitant dissociation of local and global visual processes in the two patients supports the view that prosopagnosia as well as alexia are the most conspicuous aspects of more general alterations of visual perception.

Agnosia↗