The Japanese journal of neuropsychology

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ArticleTitle	Development of dual-route theory for reading and writing impairments
Language	J
AuthorList	Yasuhisa Sakurai
Affiliation	Department of Neurology, Mitsui Memorial Hospital
Publication	Japanese Journal of Neuropsychology: 34 (1), 2-8, 2018
Received
Accepted
Abstract	Recent advancements in functional imaging have revealed two information streams. In repetition/auditory comprehension, a dorsal route plays the part of phonology to articulation conversion, travelling through the arcuate fasciculus, whereas a ventral route plays the part of phonology to semantics, proceeding from the superior temporal gyrus to the orbitofrontal gyrus via the uncinate fasciculus. In reading/written comprehension, on the other hand, the authors suggested another dual-route: a dorsal route goes from the visual cortex to the posterior superior temporal gyrus, and converts graphemes to phonemes successively, whereas a ventral route goes from the visual cortex to the posterior inferior temporal cortex, and plays the part of whole-word recognition. Besides, in writing to dictation, the authors proposed the other dual-route hypothesis: a phonological route conveys phonological information on words proceeding from the auditory cortex to the frontal lobe via the arcuate fasciculus, whereas an orthographic route conveys orthographic images of words, going from the posterior inferior temporal cortex to the frontal hand area through the parietal lobe. These dual-route hypotheses should be validated further with the development of neuroimaging techniques.
Keywords	reading and writing impairments, dual-route hypothesis, kanji and kana, alexia, agraphia