| Co-Investigator(Kenkyū-buntansha) |
GRAYBIEL Ann M. Massachusetts Inst.Tec.Dept.Brain & Cogn.Sci.Professor, 工学部, 教授
WATANABE Masahiko Hokkaido Univ.Sch.Med.Dept.Anat.Associate professor, 医学部, 助教授 (70210945)
SHIMA Keisetsu Tohoku Univ.Sch.Med.Dept.Physiol.Research Associate, 医学部, 助手 (60124583)
MUSHIAKE Hajime Tohoku Univ.Sch.Med.Dept.Physiol.Associate professor, 医学部, 助教授 (80219849)
KURATA Kiyoshi Hirosaki Univ.Sch.Med.Dept.Physiol.Professor, 医学部, 教授 (30170070)
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| Research Abstract |
To understand functional organization of the motor areas in the frontal cortex, we planned and performed an integrative research project. Using primates as experimental animals, we conducted a series of experiments with a combined physiological and molecular approach.
Researchers in Tohoku University visited MIT in Boston, and professors at MIT visited Tohoku University to advance mutual development of research works in each project, and joint works have done. As a result of intensive exchanges of ideas and collaborative works, the following results have been obtained. A novel aspect of functional organization of cortico-basal ganglia loops has been found. Although it has been established that the output from the basal ganglia is divided into two parts, direct and indirect pathway, neither their relationships with cortical motor areas nor their functional significance were known. ln the present study, we first mapped the primary motor cortex with physiological techniques, and then appli
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ed intracortical microstimulation (ICMS) for a period of 2 hrs. Immediately thereafter, brains were perfused, sectioned, and processed for immunohistochemistry to identify IEGs (c-fos and jun-B). At the same time, cells were immuno-stained for Enkephalin. IEG positive cells were found to be largely positive for Enkephalin, indicating that the cortico-striatal cells projecting from the primary motor cortex mostly belong to the indirect pathway. We subsequently found that a majority of IEG positive cells following stimulation of the supplementary motor area are not Enkephalin positive, indicating that the SMA projection to the striatum mainly belong to the direct pathway. These findings provide a new insight about functional roles of the cortico-basal ganglia pathway in motor control. In a separate project, we analyzed the distbution of subunits of NMDA glutamate receptors in cortical motor areas of primates. For this purpose, we first marked cortical areas after physiological identification. Subsequently, in situ hybridization method was applied to find subunits epsilon1, epsilon2, and xi of NMDA receptors.
The subunit distribution differed greatly in different cortical layrs in the prefrontal, premotor, primary motor, and somatosensory cortex. Less
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