2007 Fiscal Year Final Research Report Summary
Rearch of neuronal activity underlying formation of various long-term memory.
| Project/Area Number |
16330140
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Experimental psychology
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| Research Institution | Kyoto University |
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Principal Investigator |
SAKURAI Yoshio Kyoto University, Graduate School of Letters, Professor (60153962)
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| Project Period (FY) |
2004 – 2007
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| Keywords | long-term memory / neuronal circuit / neuronal activity / synapse / ICA / hippocampus / frontal cortex / rats |
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| Research Abstract |
(1) For rats, we developed several behavioral tasks to see processes of formation of various long-term memory. One example of the task was conditional discrimination, in which the rats were required to associate conditional tones(high or low) and response holes (right or left). The rats acquired the task in a few days, during which we recorded multi-neuronal activity from their hippocampal formation and neocortical frontals cortex.
(2) We developed new techniques, i.e., electrode, head-amp, microdrive, and spike-sorting system, to record and analyze multi-neuronal activity in the behaving animals. These techniques could be applied to brain-machine interface (BMI).
(3) The most remarkable one of the newly developed techniques is a new method to detect precise sub-millisecond interactions among neurons in freely behaving animals. The technique uses a combination of independent component analysis (ICA) and newly developed multi-electrodes. That is an in vivo electrophysiological technique capable of real-time and automatic sorting of extracellular activity of closely neighboring single-neurons to detect their sub-millisecond interactions even via gap-junctions (electrical synapses). The technique also could detect dendritic backpropagation of action potentials and electrically coupled cells via gap junctions.
(4) We succeeded to separate extracellular signals from the soma and those from the dendrite of a single CA1 neuron by the unique method. Then we examined spatial information coded by spikes from the soma and dendrite of CA1 neurons when the rats were moving in an open environment. The results indicate that the somatic spikes had single place fields and showed higher spatial specificity than the dendritic spikes. Therefore we conclude that a hippocampal pyramidal neuron has the ability to transform redundant spatial information received from upstream neurons via the dendrites into more place-specific information along the dendrosomatic axis.
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