University of Essex, Colchester, UK.
Cogn Neuropsychol. 2001 Jun 1;18(4):307-21. doi: 10.1080/02643290042000107.
This paper describes the case of a unilateral agraphic patient (GG) who makes letter substitutions only when writing letters and words with his dominant left hand. Accuracy is significantly greater when he is writing with his right hand and when he is asked to spell words orally. GG also makes case errors when writing letters, and will sometimes write words in mixed case. However, these allograph errors occur regardless of which hand he is using to write. In terms of cognitive models of peripheral dysgraphia (e.g., Ellis, 1988), it appears that he has an allograph level impairment that affects writing with both hands, and a separate problem in accessing graphic motor patterns that disrupts writing with the left hand only. In previous studies of left-handed patients with unilateral agraphia (Zesiger & Mayer, 1992; Zesiger, Pegna, & Rilliet, 1994), it has been suggested that allographic knowledge used for writing with both hands is stored exclusively in the left hemisphere, but that graphic motor patterns are represented separately in each hemisphere. The pattern of performance demonstrated by GG strongly supports such a conclusion.
本文描述了一例单侧失写症患者（GG），他仅在使用优势手的左手书写字母和单词时出现字母替代。当他用右手书写或被要求口头拼写单词时，准确性显著提高。GG 在书写字母时也会出现大小写错误，有时会混合大小写书写单词。然而，这些字母替代错误无论他使用哪只手书写都会出现。根据外周失写症的认知模型（例如，Ellis，1988），他似乎存在影响双手书写的字母层面障碍，以及单独的图形运动模式问题，仅干扰左手书写。在先前对单侧失写症的左利手患者的研究中（Zesiger & Mayer，1992；Zesiger，Pegna，& Rilliet，1994），有人提出，用于双手书写的字母知识仅存储在左半球中，而图形运动模式则分别在每个半球中表示。GG 表现出的模式强烈支持这样的结论。
