2000 Fiscal Year Final Research Report Summary
Switching Mechanisms Underlying Production of Motor Pattern Controlling Multiple Behavior in the Crustacean Stomatogastric Nervous System
Project/Area Number |
09640807
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
動物生理・代謝
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Research Institution | Nara University of Education |
Principal Investigator |
TAZAKI Kenro Nara University of Education School of Education, Professor, 教育学部, 教授 (40031570)
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Project Period (FY) |
1997 – 2000
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Keywords | Sromatogastric nervous system / Crustacea / Motor pattern / Behavior / Central pattern generator / Neural network / Neural input / Evolution |
Research Abstract |
Motor neurons controlling four subsystems of the crustacean foregut, oesophagus, cardiac sac, gastric mill, and pylorus, are contained in the stomatogastric nervous system. These neurons are connected to each other by electrical and chemical inhibitory synapses to construct pattern-generating neural networks. The individual neural networks can be active with different rhythms to produce characteristic motor patterns. We have employed the stomatogastric nervous system and the motor apparatus of the genus Penaeus that is the most primitive species among Decapoda crustacean. Comparative analyses among different decapod infraorders have been made with structure of the foregut, motor neurons and their innervating muscles, neurotransmitters, and neural circuits to propose how the neural networks changed and evolved for the production of motor patterns underlying characteristic behaviour. The neural networks are relatively stable due to ancestral constraints, while the peripheral motor system
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s are variable during the course of evolution. Some interactions are observable among the pattern-generating networks that control the foregut motor systems composed of four subsystems. Several neurons in the pyloric network move from the pyloric to the gastric pattern under some conditions, and all of the gastric neurons can be active with the pyloric pattern. Such plasticity of pattern-generating network is caused by extensive synaptic interactions between interneurons and motor neurons constructing the networks, and it makes them possible to produce flexible motor patterns. In the stomatogastric neural networks, motor neurons can be switched from one pattern to another by changing their intrinsic cellular properties and synaptic strength under the influence of extrinsic neural input. Switching of motor patterns can be seen under the control of the higher center (brain and commissural ganglia) that contain input neurons. These neurons can modify the frequency, duration and phase of bursting activity of network neurons through excitatory synapses to move from one network to others. Thus, the pattern-generating network results in functional reconfiguration to produce new motor patterns. Such multifunctional neural networks can control motor systems that are more variable from species to species in decapods. Modulation of neural networks by neuromodulators released from input neurons contribute to configuration of dynamic neural networks that can produce an enormous variety of motor patterns. Less
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Research Products
(8 results)