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- 2000 Conference Abstracts
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- 中井敏晴
- Post-stimulus response in the hemodynamics observed by functional magnetic resonance imaging - difference between the primary sensorimotor area and the supplementary motor area,
- The blood oxygen level dependency(BOLD) contrast is a useful tool for functional neuroimaging based on the hemodynamic response to neuronal activation. We observed different hemmodynamic responses in the BOLD signal between the primary sesnorimortor area(SM1) and the supplementary motor area(SMA)in the sequential finger movement task. In the SMA, a strong initial overshoot and a post-stimulus overshoot were observed. It was hypothesized from the time course a nalysis that the stronger initial overshoot reflected the activation of the SMA for motor control programming in the initial phase. Although the post-stimulus overshoot may be partially explained by cerebral blood flow(CBS)-cerebral blood volume(CBV)uncoupling, its mechanism remained unknown. In the SM1,only the initial overshoot was observed and the level of BOLD signal was almost constant after the initial overshoot durinig the task period.These observations suggested that the BOLD signal is characterized by both CBF-CBV uncoupling and the neuronal activation characteristics in each region.
- 岡田知久
- Naming of animals and tools: a functional magnetic resonance imaging study of categorical differences in the human brain areas commonly used for naming visually presented objects
- To investigate the neural substrates for naming objects and their category-dependency, we performed functional magnetic resonance imaging (fMRI) with naming of animals and tools. Naming objects, irrespective of their category, activated left frontal to bilateral parietal regions and occipital to posterior temporal regions. Within these areas, naming animals caused more activation of the primary visual cortex bilaterally and the ventral occipital cortex to the inferior temporal area on the right side. Naming tools caused more activation of the posterior part of the left middle temporal area, the rostral part of the left inferior parietal lobule,and the left inferior frontal cortex. These findings suggest that the neural network for naming objects has discrete category-dependent nodes through which pertinent conceptual knowledge may be mediated.
- 小澤福示郎
- The effects of listening comprehension of various genres of literature on response in the linguistic area:an fMRI study
- Using fMRI at a static magnetic field strength of 1.5 T, we investigated how comprehension and humor of sentences would correlate to activation of the language areas in listening comprehension of a native language. Sentences with a high comprehension score augmented activation in the left inferior parietal lobule and posterior part of the left superior temporal gyrus, which may be related to semantic processing. Sentences with a high humor score induced activation in Broca's area, which may be associated with syntactic processing and auditory working memory. Furthermore, sentences with a high humor factor and/or a low comprehension score activated the middle frontal gyrus, which may be attributed to auditory working memory.
- 松尾香弥子
- Dissociation of writing processes: functional magnetic resonance imaging during writing of Japanese ideographic characters
- Dissociation between copying letters and writing to dictation has been reported in the clinical neuropsychological literature.Functional magnetic resonance imaging(fMRI)was conducted in normal volunteers to detect the neurofunctional defferences between 'copying Kanji',the Japanese ideographic chracters,and 'writing Kanji corresponding to phonological information'.Four tasks were conducted:the copying-Kanji task,the superior parietal lobule was extensively activated during the copying-Kanji task;(a model of the copying letters process)and the Kanji-grapheme-puzzle task.These observations suggested that this area was involved in referring the visual stimuli closely related to the ongoing handwriting movements. On the other hand,Broca's area,which is crucial for language production,was extensively activated during the writing-Kanji-corresponding-to-phonogram task(a model of the writing-to-dictation proces). The Kanji-grapheme-puzzle task activated the bilateral border portions between the inferior parietal lobule and the occipital lobe,the left premotor area,and the bilateral supplementary motorarea(SMA).SInce the Kanji-grapheme-puzzle task involved manipulospatial characteristics,these results suggested cooperation between visuospatial and motor executive functions,which may be extensively utilized in demanding visual language processing. The neurofunctional defference between 'copying Kanji'and'writing Kanji corresponding to phonogram' was efficiently demonstrated by this fMRI experiment.