Mechanism of thalamo -cortical projection and intracerebral association

Research Project

Project/Area Number	02670370
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Neurology
Research Institution	Unversity of Occupational and Environmental Health
Principal Investigator	TSUJI Sadatoshi Department of Neurology, University of Occupational and Environmental Health, School of Medicine Assistant Professor, 医学部, 講師 (30117171)
Project Period (FY)	1990 – 1992
Project Status	Completed (Fiscal Year 1992)
Budget Amount *help	¥2,400,000 (Direct Cost: ¥2,400,000) Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1990: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	SEP / SI area / SII area / Sleep stages / Somatosensory pathway / Topography / Acetylcholine / アセチールコリン / マイクロダイアライシス / ニューロトランスミッター / ネコ大脳皮質誘発電位 / 上肢電気刺激 / 睡眠ステ-ジ / 頭皮上分布メカニズム / トポグラフィ- / 一次大脳感覚野 / 大脳皮質誘発電位 / 電気刺激 / 遠隔電場電位
Research Abstract	The mechanism of thalamo-cortical projection and intracerebral association system in the somatosensory pathways was studied in normal volunteers and cats. Cortical and subcortical somatosensory evoked potentials (SEPs) were recorded from the scalp, skull, dura mater, supra-and intra-cortex to evaluate the function of somatosensory pathways and primary sensory cortex (SI) in normal volunteers and cats. Topography of cortical SEPs over the scalp in normal controls during sleep stage revealed that cortical components (N20, P20, P22, P23 and N24) showed morphological changes and delayed peak latencies during sleep stage II and III/IV, and returned to the initial morphologies and peak latencies during REM sleep. These findings suggest that NREM sleep affects the origins of cortical SEPs which could be related to the synaptic function in the sensory cortex. Cortical and intracortical SEPs were recorded from the scalp, skull, dura mater, supra- and intra-cortex in cats. Morphologies and peak latencies of SEPs were essentially different between supra- and intra-cortical SEPs and scalp SEPs. Furthermore, cortical SEPs recorded from the medial, central and lateral SI areas with 3 to 5 mm intervals over the cortex were quite different morphologies and latencies in each electrode. These findings suggest that somatosensory pathways from the thalamus project not only to the SI areas but to frontal and parietal cortices. It is impossible to record cortical SEPs from both secondary sensory cortices (SII areas) in the cats. Neurotransmitters from the SI, motor and parietal cortices of the cats were analysed before, during and after the electrical stimulation of the radial nerve. The electrical stimulation of the radial nerve increased the acetylcholine release in the contralateral primary sensory area (SI) and motor area. Cholinergic transmission may be involved in the mechanism of cortical SEP generation.