PubMed · 6487092
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R J Uitti, J R Donat, K Romanchuk. 1984. Pure alexia without hemianopia.. https://doi.org/10.1001/archneur.1984.04050220024007
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In this single case report we describe our further observations of a patient (ROC) with a classical spelling dyslexia. A word length effect and a script effect were demonstrated. No evidence of semantic processing was obtained with brief tachistoscopic presentations. Single letter identification was unimpaired. In a series of experiments it was shown that her letter-by-letter reading strategy was mediated by explicit letter naming. In particular, it was observed that with successive presentation of the individual letters there was a stepwise function relating her whole word reading to the single letter presentation times. These durations permitted explicit letter naming. When explicit letter naming was prevented by a simultaneous articulatory suppression task, her letter-by-letter reading was significantly impaired. Her performance was compared with a second patient (MRF) who could read but could not spell. His reading was unaffected by articulatory suppression and significantly impaired by a successive presentation of the individual letters of a word. It is argued that explicit letter naming provides an input to the spelling system and thus can be recognized as orally spelled words. We conclude that in the reading-impaired patient there was a lexical deficit compensated for by the operation of a component of her intact spelling system.
In three repetition priming experiments that employed identical (e.g., DOG-DOG) and reversed repetitions (e.g., GOD-DOG), it was found that relative to controls (e.g., DOG-DOG), GOD-type words did not prime DOG-type words. Also, neither DUT-type nor TUD-type nonwords primed DUT-type nonwords. In Experiments 1 and 2, these results occurred using both long- and short-term repetition priming conditions, respectively. In Experiment 3, the word results held under conditions of short-term priming coupled with stimulus misorientation. However, the nonword results resembled the word results (i.e., identical but not reversed repetitions primed nonwords). The failure to provide explicit evidence for direct visual access (e.g., GOD does not prime DOG while DOG does) irrespective of other sources of lexical activation supports theories of words recognition that postulate multiple and varied lexical representations that are activated through a matrix of connections.
We described a 55-year-old, right-handed, university-educated Japanese man who showed pure alexia after an infarction in the territory of the left posterior cerebral artery. Damage to the corpus callosum was limited to the most caudal part of the splenium. In the early days of his illness, he demonstrated the inability to read aloud on either Kana (Japanese syllabograms) or Kanji (Japanese morphograms). In contrast, he could semantically categorize Kanji-words such as animals or non-animals. Subsequently, he gradually regained the ability of reading aloud Kanji as well as Kana. At that time, we further investigated the relation between his reading ability and the attributes of 881 Kanji characters including hieroglyphicity, concreteness, and familiarity. We found that he could more readily read Kanjis with higher hieroglyphicity, concreteness, and familiarity. The reading times for Kanji-words were significantly shorter than those of corresponding Kana-words. Moreover, he showed some difficulty to read Kana-words and Kana combinations without meaning when asked to perform repetitive opposing movements with his thumb and little finger inhibiting kinesthetic reading. The effect was not observed when he read Kanji-words. These results lead us to suggest the following: (1) the two components of reading, reading aloud and comprehension abilities, are dissociable in a pure alexic, especially in Kanji reading; and (2) recovery mechanisms underlying Kanji and Kana reading were different in our case. Namely, restitution of the direct connection through the residual splenium fibers between the visual word form processing area in the right hemisphere and the left angular gyrus was attributed to Kanji reading, and utilization of kinesthetic reading played an important role in Kana reading.