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Summary of Research Projects (Supports in 2004
Fiscal Year)
| Subjects |
Mechanisms for the generation and maintenance of brain
asymmetry |
| Representative researcher |
Faculty of Sciences,Kyushu University
Isao ITO |
| Asymmetrical hemispheric specialization
is a fundamental concept of brain science and has been described
mainly in higher-order functions of the brain. Recently we
have found that synaptic distribution of NMDA receptor NR2B
subunits in mouse hippocampus is asymmetrical between the left
and right, and between the apical and basal dendrites of single
neurons. These asymmetrical allocations of NR2B subunits differentiate
the properties of NMDA receptors and synaptic plasticity between
the left and right hippocampus. Our findings show that asymmetries
are involved even in a basic structure and function of simple
neuronal network. In order to elucidate molecular mechanisms
for the generation and maintenance of hippocampal asymmetry,
we have tried two distinct approaches in the present study.
One is the experiment using a mutant mouse strain (iv mouse)
that shows abnormalities in the left-right asymmetry of internal
organs. The other one is organotypic co-culture system composed
of micro slices prepared from the CA1 and CA3 areas of mouse
hippocampus. We found that iv mutation resulted in the loss
of left-right asymmetry of hippocampal circuitry, whereas apical-basal
asymmetry of single neuron remained intact. Our results indicate
that mechanisms for the generation of left-right asymmetry
differ between endodermal tissues (internal organs) and ectodermal
tissues (such as the brain), and that at least two types of
information (left-right of the brain, apical-basal of the neuron)
are required for the establishment of brain asymmetry. |
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