Ischebeck Anja, Indefrey Peter, Usui Nobuo, Nose Izuru, Hellwig Frauke, Taira Masato
University of Nijmegen, The Netherlands.
J Cogn Neurosci. 2004 Jun;16(5):727-41. doi: 10.1162/089892904970708.
In order to separate the cognitive processes associated with phonological encoding and the use of a visual word form lexicon in reading, it is desirable to compare the processing of words presented in a visually familiar form with words in a visually unfamiliar form. Japanese Kana orthography offers this possibility. Two phonologically equivalent but visually dissimilar syllabaries allow the writing of, for example, foreign loanwords in two ways, only one of which is visually familiar. Familiarly written words, unfamiliarly written words, and pseudowords were presented in both Kana syllabaries (yielding six conditions in total) to participants during an fMRI measurement with a silent articulation task (Experiment 1) and a phonological lexical decision task (Experiment 2) using an event-related design. Consistent over two experimental tasks, the three different stimulus types (familiar, unfamiliar, and pseudoword) were found to activate selectively different brain regions previously associated with phonological encoding and word retrieval or meaning. Compatible with the predictions of the dual-route model for reading, pseudowords and visually unfamiliar words, which have to be read using phonological assembly, caused an increase in brain activity in left inferior frontal regions (BA 44/47), as compared to visually familiar words. Visually familiar and unfamiliar words were found to activate a range of areas associated with lexico-semantic processing more strongly than pseudowords, such as the left and right temporo-parietal region (BA 39/40), a region in the left middle/inferior temporal gyrus (BA 20/21), and the posterior cingulate (BA 31).
为了区分与语音编码以及阅读中视觉词形词典使用相关的认知过程，将以视觉上熟悉的形式呈现的单词与视觉上不熟悉的形式呈现的单词的加工过程进行比较是很有必要的。日语假名拼写提供了这种可能性。两种语音等效但视觉上不同的音节表使得例如外来借词可以用两种方式书写，其中只有一种在视觉上是熟悉的。在功能磁共振成像测量期间，将熟悉书写的单词、不熟悉书写的单词和假词以两种假名音节表呈现给参与者（总共产生六种条件），同时进行无声发音任务（实验1）和语音词汇判断任务（实验2），采用事件相关设计。在两项实验任务中一致发现，三种不同的刺激类型（熟悉的、不熟悉的和假词）选择性地激活了先前与语音编码以及单词检索或意义相关的不同脑区。与阅读的双通道模型的预测一致，与视觉上熟悉的单词相比，必须通过语音组合来阅读的假词和视觉上不熟悉的单词会导致左下额叶区域（BA 44/47）的脑活动增加。结果发现，视觉上熟悉和不熟悉的单词比假词更强烈地激活了一系列与词汇语义加工相关的区域，如左右颞顶叶区域（BA 39/40）、左中/颞下回的一个区域（BA 20/21）以及后扣带回（BA 31）。
