| Budget Amount *help |
¥19,760,000 (Direct Cost: ¥15,200,000、Indirect Cost: ¥4,560,000)
Fiscal Year 2010: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2009: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2008: ¥9,360,000 (Direct Cost: ¥7,200,000、Indirect Cost: ¥2,160,000)
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| Research Abstract |
Neurons integrate synaptic inputs arriving on their soma and dendrites and generate action potentials at a frequency depending on the level of depolarization resulting from that integration at the initial segment of their axon. The action potentials are conducted along their axons to their terminals and transfer signals to other neurons at synaptic junctions. This is the basic method of signal transmission between neurons. We recently found that, in visual cortex, action potentials generated in a single layer 2/3 pyramidal (excitatory) neuron can reliably evoke large inhibitory postsynaptic currents in other nearby pyramidal cells, via axo-axonic ionotropic glutamate receptor-mediated excitation of nerve terminals of inhibitory interneurons, which connect to the target pyramidal cells. In this study, I further investigated the mechanism of this new form of synaptic transmission. In addition to AMPA/kainite receptors, an analysis of the miniature inhibitory synaptic currents recorded from pyramidal neurons demonstrated the presence of NMDA receptors on the inhibitory terminals that targeted the recorded neuron. Dual whole-cell recording from adjacent pyramidal neurons showed that those NMDA receptors contributed to the excitatory synaptic transmission from the axon terminals of the pyramidal neuron to the inhibitory nerve terminals, which initiated GABA release from the latter terminals to the target pyramidal neuron.
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