Pure Alexia
نویسندگان
چکیده
Pure alexia is a reading disorder that occurs in literate individuals secondary to a lesion in the left occipito-temporal region. The hallmark of this deficit is the word-length effect: the naming latencies of patients increase dramatically with increasing numbers of letters in the word. For example, every additional letter can take a further 3 s for a patient who is reading a word aloud [compared with 9 ms for a normal agematched reader; Behrmann et al., 1998 (P728)]. Pure alexia is also known as letter-by-letter reading, spelling dyslexia, alexia without agraphia, verbal dyslexia, word blindness or letter-by-letter dyslexia. Pure alexia was first extensively described by Déjerine. This reading pathology is a key syndrome in the ‘language zone’ theory of the French neurologist. In his book entitled ‘Sémiologie des affections du système nerveux’ (1914), Déjerine describes pure alexia as a disconnection syndrome that isolates the ‘center for the optic images of letters’, situated in the left angular gyrus, from both visual cortices. Because this language center cannot be accessed through visual stimulation, the patients cannot read. However, they are still able to write, speak and understand speech because the lesion is peripheral, i.e. out of the language zone per se. Alexia is said to be ‘pure’ because it is not associated with any other language disorders. Following Déjerine’s work, many neurologists have attempted to locate the exact reading pathway in the human brain [see Black and Behrmann (1994) for a review]. They were either interested in the minimal pathway necessary for reading, or in the potential existence of a common pathway for reading and visual object perception or color perception [Woods and Pöppel, 1974 (P774); Michel et al., 1979 (P760); Chanoine et al., 1998 (P736)]. The account that the neurologists have defended or tried to falsify is the hypothesis of a disconnection between the visual areas and the language zone (the left angular gyrus) being responsible for pure alexia [Déjerine, 1892 (P739); Déjerine and Vialet, 1893 (P740); Greenblatt, 1973, 1976, 1990 (P744–746); Stachowiak and
منابع مشابه
Rehabilitation of pure alexia: A review
Acquired reading problems caused by brain injury (alexia) are common, either as a part of an aphasic syndrome, or as an isolated symptom. In pure alexia, reading is impaired while other language functions, including writing, are spared. Being in many ways a simple syndrome, one would think that pure alexia was an easy target for rehabilitation efforts. We review the literature on rehabilitation...
متن کاملWord-Superiority in Pure Alexia
Pure alexia is an acquired reading disorder where patients lose the ability to read fast and fluently, but are commonly able to identify words letter-by-letter. This is evidenced by a pronounced word-length effect in reading, where reaction times (RTs) increase linearly with word length. The severity of the reading deficit in pure alexia has been reported to be systematically related to perform...
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Exaggerated effects of word length upon reading-aloud performance define pure alexia, but have also been observed in semantic dementia. Some researchers have proposed a reading-specific account, whereby performance in these two disorders reflects the same cause: impaired orthographic processing. In contrast, according to the primary systems view of acquired reading disorders, pure alexia result...
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Reading impairments of three alexia patients, two pure alexia and one alexia with agraphia, due to different lesions were examined quantitatively, using Kanji (Japanese morphogram) words, Kana (Japanese phonetic writing) words and Kana nonwords. Kana nonword reading was impaired in all three patients, suggesting that widespread areas in the affected occipital and occipitotemporal cortices were ...
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Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared the eye movements of four patients with pure alexia to controls with simulated visual field defe...
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