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At least 19 recordsLinked to original sources
PubMed1998

Visual complexity in letter-by-letter reading: "pure" alexia is not pure.

Standard accounts of pure alexia have favoured the view that this acquired disorder of reading arises from damage to a left posterior occipital cortex mechanism dedicated to the processing of alphanumeric symbols. We challenge these accounts in two experiments and demonstrate that patients with this reading deficit are also impaired at object identification. In the first experiment, we show that a single subject, EL, who shows all the hallmark features of pure alexia, is impaired at picture identification across a large set of stimuli. As the visual complexity of pictures increases, so EL's reaction time to identify the stimuli increases disproportionately relative to the control subjects. In the second experiment, we confirm these findings with a larger group of five pure alexic patients using a selected subset of high- and low-visual complexity pictures. These findings suggest that the deficit giving rise to pure alexia is not restricted to orthographic symbols per se but, rather, is a consequence of damage to a more general-purpose visual processing mechanism.

Adult↗
PubMed1985

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.

Aged↗
PubMed1995

Visual word activation in pure alexia.

A patient with pure alexia (DM) is shown to perform rapid and accurate lexical decisions for common words without the ability to recover their complete identity. We provide evidence using a speeded decision task that DM is not forced to rely on a laborious analysis of individual letter forms when judging the lexical status of orthographic patterns varying in length, though he clearly must use this approach to fully identify a word for explicit report. By contrast, the ability to rapidly classify a word apparently does not extend to judgements of its superordinate category. DM makes semantic decisions for visual words by adopting the same inefficient procedure he uses for verbal report of their identity. The results provide further constraints on the functional deficit responsible for pure alexia. We argue that DM is able to monitor the overall activation of word units without achieving full identification and that such a process may be a characteristic of the normal reading mechanism.

Adult↗
PubMed1997

Music alexia in a patient with mild pure alexia: disturbed visual perception of nonverbal meaningful figures.

A 26-year-old female pianist suffered from an intracerebral hematoma caused by an arteriovenous malformation of the left occipital parasplenial region, which was operated on seven months after the onset. Incomplete right hemianopsia, mild pure alexia, and partially disturbed naming of visual objects persisted several months after the removal of the malformation. Evaluation of musical ability one and three months after surgery showed that her auditory recognition of music was intact. She could sing and play melodies already learned and could dictate well the notes after hearing tones. However, she had difficulty in reading music, especially the pitch of notes, even for simple sequences of 4 notes. In contrast, her rhythm reading was fairly good. Her visual recognition of other symbolic figures like road signs was also markedly impaired. These results suggest that her visual recognition of written music as well as of other symbolic figures underwent a preliminary verbal decoding in the left hemisphere and that pitch reading was more dependent on verbal processing than rhythm reading.

Adult↗
PubMed1989

Evidence for preserved reading in 'pure alexia'.

We describe 4 patients who developed pure alexia after infarctions of the left cerebral hemisphere. All subjects employed a letter-by-letter strategy (with varying degrees of success) to explicitly identify visually presented words. Although all 4 subjects explicitly denied that they could identify briefly presented words, they all performed significantly better than chance on lexical decision and forced-choice semantic categorization tasks with briefly presented words which they could not explicitly identify. Three subjects regained the ability to explicitly identify briefly presented words; these subjects were more accurate with nouns than functors and words of high as compared with low imageability. Additionally, these subjects were impaired in the processing of suffixes. These data are not accommodated by the 'disconnection' account of pure alexia but are more consistent with the hypothesis that reading in these patients is mediated by the right hemisphere.

Adult↗
PubMed2000

Rapid word identification in pure alexia is lexical but not semantic.

Following the notion that patients with pure alexia have access to two distinct reading strategies-letter-by-letter reading and semantic reading-a training program was devised to facilitate reading via semantics in a patient with pure alexia. Training utilized brief stimulus presentations and required category judgments rather than explicit word identification. The training was successful for trained words, but generalized poorly to untrained words. Additional studies involving oral reading of nouns and of functors also resulted in improved reading of trained words. Pseudowords could not be trained to criterion. The results suggest that improved reading can be achieved in pure alexia by pairing rapidly presented words with feedback. Focusing on semantic processing is not essential to this process. It is proposed that the training strengthens connections between the output of visual processing and preexisting orthographic representations.

Dyslexia↗
PubMed1995

The efficacy of kinesthetic reading treatment for pure alexia.

This paper presents an effective treatment for pure alexia by a type of single-case design, which we termed a "material-control single-case design" [Sugishita et al., Neuropsychologia, Vol. 31, 559-569, 1993]. Two patients with pure alexia were treated using kinesthetic reading (reading by tracing or copying the outline of each letter with the patient's finger). The results clearly demonstrated that both patients significantly improved their reading and copying performances. Their recovery of reading performance arose from improvement in copying. The results of tachistoscopic reading tests suggested that the patient obtained the ability to read without kinesthetic movements.

Adult↗
PubMed1993

Jules Dejerine and his interpretation of pure alexia.

Dejerine's interpretation of pure alexia is routinely mentioned in all neuropsychological textbooks, yet the details of his account and the evidence on which it is based have never been subjected to a critical analysis. We provide such an evaluation in this paper, summarizing the behavioral data that Dejerine presented in his now famous case report and the theoretical framework he adopted to explain the phenomenon of alexia without agraphia. We also provide a link between Dejerine's work and current hypotheses on the nature of the syndrome.

Brain↗
PubMed2001

The functional anatomy of single-word reading in patients with hemianopic and pure alexia.

We investigated single-word reading in normal subjects and patients with alexia following a left occipital infarct, using PET. The most posterior brain region to show a lateralized response was at the left occipitotemporal junction, in the inferior temporal gyrus. This region was activated when normal subjects, patients with hemianopic alexia and patients with an incomplete right homonymous hemianopia, but no reading deficit, viewed single words presented at increasing rates. This same area was damaged in a patient with pure alexia ("alexia without agraphia") and no hemianopia, who read words slowly using a letter-by-letter strategy. Although the exact level of the functional deficit is controversial, pure alexia is the result of an inability to map a percept of all the letters in a familiar letter string on to the mental representation of the whole word form. However, the commonest deficit associated with "pure" alexia is a right homonymous field defect; an impairment that may, by itself, interfere with single-word reading because of inability to see the letters towards the end of a word. The relative contributions of pure and hemianopic alexia in individual patients needs to be assessed, as the latter has been shown to respond well to specific rehabilitation programmes.

Adult↗
PubMed1998

[Pure alexia due to a fusiform gyrus lesion].

We present a patient with pure alexia following a hemorrhagic infarction in the left fusiform gyrus. The symptom began with alexia preferentially disturbed for kana, but during the course of recovery slight agraphia for kanji became pronounced. In the earlier phase, alexia was more severe than agraphia and he could write kanji that he could not read. Furthermore, kinesthetic reading was effective. These findings are consistent with the symptoms of pure alexia, although the fact that a writing disturbance for kanji persisted resembles the profile of alexia with agraphia for kanji due to a posterior inferior temporal lesion. Based on the fact that the posterior inferior temporal lesion showed more severe agraphic symptom and more frequent nonresponse writing errors of kanji, and that our patient's lesion was mainly located in the fusiform gyrus that is medial to the inferior temporal gyrus, we believe that alexia occurred when the inferior temporal gyrus was disconnected from the fusiform gyrus, as a result, visual information could not reach the inferior temporal gyrus in which the visual images of individual kanji are stored.

Aged↗
PubMed1998

[Pure alexia: presentation of a case].

INTRODUCTION AND CLINICAL CASE: A case of pure alexia, secondary to an occipital cerebral infarct, is presented, which initially appearing with bilateral amaurosis of two hours of duration, following by a significant difficulty to read, and according to patient, was a deficit to near vision and by criteria of ophthalmologists and optometrists was a presbyopia. Authors identified a lack of P-300 wave in study of endogenous component of events related potentials (ERP), to task of phonetic discrimination, and its normal registry to task of graphic discrimination. CONCLUSION: Therefore, we confirm the cliniconeurophysiologic diagnosis of a pure alexia without agraphia, by means of this non-invasive method studying cerebral cognitive process.

Cerebral Infarction↗
PubMed1995

[A case of pure alexia whose writing ability with eyes closed was superior to that with eyes open].

We compared the writing ability between eyes open (looking at one's writing) and eyes closed (without looking) in a case of pure alexia. The patient is a 84-year-old right handed man who developed pure alexia following an infarction in the distribution of the left posterior cerebral artery. He showed right homonymous hemianopsia, slight memory disorder and slight anomia. He could not read any kinds of letters and words at all though he could categorize letters: Kana (phonograms), Kanji (morphograms) and Arabic numbers, and he could distinguish the real letters from false ones. He could achieve almost 60-70% of Kana and Kanji dictation, though it was not perfect. He was often confused and could not continue writing correct letters once interrupted. He wrote poorly when looking at what he was writing. So we compared the ability of dictation with his eyes closed, and that with his eyes open. We found the former way never caused confusion and got better results, which was statistically significant (Fisher's exact test (p < 0.05)). It seemed that his visual feedback of his own writing rather caused trouble in his writing. Thus we concluded that input (reading) process and output (writing) process work simultaneously and bi-directionally. Slight impairment of writing in pure alexia patients might be caused by the effect of impairment of input (reading) process, which is simultaneously connected with the output (writing) process.

Aged↗
PubMed1993

Reading in pure alexia. The effect of strategy.

A number of investigators have demonstrated that patients with pure alexia comprehend briefly presented words which they are unable to explicitly identify. We suggested previously that these patients may read by means of two distinct procedures: a laborious letter-by-letter method and a 'whole-word' procedure which, at least initially, does not support explicit word identification. We report a test of this proposal in a patient with pure alexia. We reasoned that if the patient had access to two distinct and incompatible procedures, he might be induced to switch from one to the other by changing task demands. We found that when instructed to name words, the patient employed a letter-by-letter strategy; in contrast, when instructed to make lexical decision or semantic judgements about rapidly presented words, he appeared to use a 'whole-word' strategy. These data support the hypothesis that two distinct procedures are available to this patient. We argue, further, that is necessary to suppress use of the letter-by-letter strategy to demonstrate whole word reading capability in pure alexics, and that failure to do so may account for negative findings in other cases reported in the literature.

Cerebral Infarction↗