The Japanese journal of neuropsychology

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ArticleTitle	Neural mechanism in writing: The process of transformation from visual letter images into motor information
Language	J
AuthorList	Machiko Kezuka
Affiliation	Rehabilitation, Aoyama Hospital
Publication	Japanese Journal of Neuropsychology: 19 (1), 22-29, 2003
Received
Accepted
Abstract	A neural mechanism of motor process in writing was proposed through four cases with agraphia. Case 1: A 53 year-old, right-handed female presented an agraphia with different features on right hand from that on left hand. It was caused by lesion from the left intraparietal sulcus to the left lateral ventricle after operation. Distortion of letter shape and winding letter lines were observed in the writing of the right hand, but errors of writing course, rotation of letters were in writing of the left hand. Case 2: A 57 year-old, right-handed male and Case 3: A 54 year-old, right-handed male exhibited agraphia with right hemisphere symptoms such as dressing apraxia, constructive disorders and so on caused by a bilateral atrophy which was more prominent in the right parietal lobe than in the left. Features in the writing of both cases showed a striking resemblance to each other. The common feature was difficulty in drawing lines as they intended. Sometimes they could not construct even a single letter shape. Case 4: A 77 year-old, right-handed female, with right unilateral agraphia due to infarction from the left posterior middle frontal gyrus to the anterior part of precentral gyrus, showed deterioration only on right hand writing. Considering these agraphic cases' writing abilities, we assumed that visual letter images are transformed into writing motor information at the left intraparietal sulcus after the visual letter images had been processed with considerable involvement by the right parietal lobe. This writing motor information is connected to language information at the left posterior middle frontal gyrus, and then forks to the right hand or the left hand, materializing as letters on paper through the premotor area to the motor areas of the right and left hand, finally.
Keywords	neural mechanism in writing, agraphia, left intraparietal sulcus, left middle frontal gyrus, right hemisphere