1988 Fiscal Year Final Research Report Summary
Neuronal network analysis of functional states in the cerebral cortex
| Project/Area Number |
62480110
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | Tokyo Metropolitan Institute for Neurosciences |
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Principal Investigator |
OSHIMA Tomokazu Tokyo Metropolitan Institute for Neurosciences, 病態神経生理学研究室・参事研 (70073062)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Cerebral cortex / Electroencephalogram / Spindle wave / Motor cortical neurones / Intracellular potentials / Rhythmic depolarizing potentials / Cat |
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| Research Abstract |
As a part of researches to elucidate a variety of functional atates of the cerebral cortex as the integrative actions of neuronal assenblies, we have analysed the neuronal mechanisms of the electrocortical spindle wave. The encephale isole cat preparations were maintained atraumatically in the sound-attenuated and electrically shielded room. The electrocorticogram was monitored on the precruciate motor cortex. The intracellular potentials of all the layer neurones were recorded nearby through the glass capillary microelectrode manipulated by a remote control from outside the room. The results were as follows: 1) The laminae V-VI neurones exhibited two types of rhythmic depolarizing potentials (RDPs), RDP-I and RDP-II, respectively in phase of type I positive and type II negative spindle waves. Their amplitudes were positively correlated in each type throughout the characteristically developing and decaying processes of the spindle. 2) These RDPs were proved to be the excitatory postsynaptic potentials (EPSPs) of dendritic origin by their amplitude changes dependent susceptively on the spontaneous membrane potential fluctuation, but contrastively little dependent on the membrane potential altered by intracellular step current injections. These dendritic characteristics were confirmed for comparison in the monosynaptic EPSPs of the same sample neurones produced by epicortical or thalamic stimulation. 3) RDPs also occurred in laminae I-III neurones as EPSPs, but with smaller amplitude and less dendritic nature than laminae V-VI neurones. These results have indicated that rhythmic components of the spindle are generated mainly by dendritic EPSPs in the deep layer neurones on which at least two different subcortical afferent inputs impinge at different depths from the cortical surface.
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