- 2004 Conference Abstracts
- 筆頭
- title
- Abstract
- 筆頭
- title
- Abstract
- 筆頭
- title
- Abstract
- Dinh Ha Duy Thuy
- Implicit and explicit processing of kanji and kana words and non-words studied with fMRI
- Using functional magnetic resonance imaging (fMRI), we investigated the implicit language processing of kanji and kana words (i.e., hiragana transcriptions of normally written kanji words) and non-words. Twelve right-handed native Japanese speakers performed size judgments for character stimuli (implicit language task for linguistic stimuli), size judgments for scrambled-character stimuli (implicit language task for non-linguistic stimuli), and lexical decisions (explicit language task). The size judgments for scrambled-kanji stimuli and scrambled-kana stimuli produced activations on the bilateral lingual gyri (BA 18), the bilateral occipitotemporal regions (BA 19/37), and the bilateral superior and inferior parietal cortices (BA 7/40). Interestingly, besides these areas, activations of the left inferior frontal region (Broca’s area, BA 44/45) and the left posterior inferior temporal cortex (PITC, BA 37), which have been considered as language areas, were additionally activated during size judgment for kanji character stimuli. Size judgment for kana character stimuli also activated Broca’s area, the left PITC, and the left supramarginal gyrus (SMG, BA 40). The activations of these language areas were replicated in the lexical decisions for both kanji and kana. These findings suggest that language processing of both kanji and kana scripts is obligatory to literate Japanese subjects. Moreover, comparison between the scrambled kanji and the scrambled kana showed no activation in the language areas, while greater activation in the bilateral fusiform gyri (left-side predominant) was found in kanji vs. kana comparison during the size judgment and the lexical decision. Kana minus kanji activated the left SMG during the size judgment, and Broca’s area and the left middle/superior temporal junction during the lexical decision. These results probably reflect that in implicit or explicit reading of kanji words and kana words (i.e., hiragana transcriptions of kanji words), although using largely overlapping cortical regions, there are still some differences. Kanji reading may involve more heavily visual orthographic retrieval and lexical-semantic system through the ventral route, while kana transcriptions of kanji words require phonological recoding to gain semantic access through the dorsal route.
- 大神優子
- An fMRI study of tool-use gestures: Body-part-as-object and pantomime
- A body-part-as-object (BPO) gesture is one of the error patterns in apraxia. In the BPO gesture, people represent objects by their hands. To clarify the neuronal background of the BPO gesture, we compared the brain activation during the BPO gesture with that during ordinary pantomime in normal subjects using functional magnetic resonance imaging. Both the BPO gesture and the pantomime induced activation in the left parietal areas (Brodmann・s area [BA] 7, 40), irrespective of the hand used. These areas might be activated by a common process of tool-related gestures. The BPO gesture also activated the right supramarginal gyrus (BA 40). This activation might reflect the characteristic process of BPO, the correlation of hands with tools by their forms and movements.
- 中井敏晴
- Application of independent component analysis to magnetic resonance imaging for enhancing the contrast of gray and white matter
- An application of independent component analysis (ICA) was attempted in order to develop a method of processing magnetic resonance images to extract physiologically independent components representing tissue relaxation times and achieve improved visualization of normal and pathologic structures. Anatomical T1-weighted, T2-weighted and proton density images were obtained from ten normal subjects, three patients with brain tumors and one patient with multiple sclerosis. The data sets were analyzed using ICA based on the learning rule of Bell and Sejnowski after prewhitening operations. The three independent components obtained from the three original data sets corresponded to 1) short T1 components representing myelin of white matter and lipids, 2) relatively short T1 components representing gray matter, and 3)long T2 components representing free water. The involvement in gray or white matter in brain tumor cases, and the demyelination in the case of multiple sclerosis were enhanced and visualized in independent component images. ICA can potentially achieve the separation of tissues with different relaxation characteristics and generate new contrast images of gray and white matter. With the proper choice of contrast for the original images, ICA may be useful not only for extracting subtle or hidden changes but also for pre-processing transformation before clustering and segmenting the structure of the human brain.