1998 Fiscal Year Final Research Report Summary
Simultaneous recording of presynaptic calcium concentration and postsynaptic responses
| Project/Area Number |
09680808
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
神経・脳内生理学
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| Research Institution | Tohoku University |
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Principal Investigator |
UMEMIYA Masashi Tohoku University, School of Medicine Department of Neurophysiology, Research associate, 医学部, 助手 (50271911)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Neuron / Calcium / Glutamate / NMA receptors / Synapse / Fluo-3 / Dendrite / AMPA / KA receptor |
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| Research Abstract |
Simultaneous recording of intracellular calcium concentration at the synapse and synaptic current from the cell body allows mapping of miniature excitatory postsynaptic currents(mEPSCs) to single synapses. In the absence of extracellular Mg , 73% of synapses had mEPSCs with fast and slow components, attributed to AMPA and NMDA type glutamate receptors. A high degree of trial to trial variation in both mEPSC and calcium transient amplitude was observed at single synapses (-30%). No periodic failure in the AMPA receptorm EPSC was observed at synapses expressing responses mediated by both receptor classes. A strong positive correlation between variation in the amplitude of the calcium transient and the slow NMDA receptor mediated mEPSC was observed. The relatively low amplitude of the NMDA receptor mediated mEPSC suggested that a small number of receptors (one to five) are involved in the quantal synaptic events and that the stochastic nature of channel activation would contribute to response variance. At synapses that had responses associated with both receptor classes, the peak mEPSC amplitude (an AMPA receptor mediated component) was positively correlated with charge influx mediated by NMDA receptors during repeated synaptic events. This result suggests that factors effecting both receptor classes such as the amount of transmitter in synaptic vesicles might contribute to the variation in mEPSC amplitude.
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