Varieties of alexia from fusiform, posterior inferior temporal and posterior occipital gyrus lesions

Article type: Research Article

Authors: Sakurai, Yasuhisa

Affiliations: Department of Neurology, Mitsui Memorial Hospital, 1 Kanda-Izumi-cho, Chiyoda-ku, Tokyo, 101-8643, Japan. Tel.: +81 3 3862 9111; Fax: +81 3 5687 9765; E-mail: [email protected]

Abstract: 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 recruited in reading Kana characters (corresponding to European syllables). In addition, the findings in patient 1 (pure alexia for Kanji and Kana from a fusiform and lateral occipital gyri lesion) and patient 2 (pure alexia for Kana from a posterior occipital gyri lesion) suggested that pure alexia could be divided into two types, i.e. ventromedial type in which whole-word reading, together with letter identification, is primarily impaired because of a disconnection of word-form images from early visual analysis, and posterior type in which letter identification is cardinally impaired. Another type of alexia, alexia with agraphia for Kanji from a posterior inferior temporal cortex lesion (patient 3), results from deficient whole-word images of words per se, and thus should be designated "orthographic alexia with agraphia". To account for these impairments, a weighted dual-route hypothesis for reading is suggested.

Journal: Behavioural Neurology, vol. 15, no. 1-2, pp. 35-50, 2004