| Budget Amount *help |
¥61,300,000 (Direct Cost: ¥61,300,000)
Fiscal Year 2001: ¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 2000: ¥47,200,000 (Direct Cost: ¥47,200,000)
Fiscal Year 1999: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Research Abstract |
Environmental information changes from moment to moment. Insects acquire and process this complex information, and display the appropriate behavior. Odor molecules float in the air and continuously change their distribution status in space in complex patterns. Insects can trace the pheromone to orient toward a mate over several kilometers away. The aim of the study is to understand how odor information is processed by the micro-brain systems of insects, and how the information participates in generating and guiding odor-oriented behavior.
In a walking moth species, Bumbyx mori, the walking toward the pheromone source is controlled by a combination of a reflex and a self-generated zigzag program, which are both triggered by intermittent pheromonal stimulation. First, males begin to show a brief straight-line walk to the same direction of the antenna where the stimulation was applied. Then the programmed sequence of the zigzag-walking pattern is initiated, which consists of zigzagging tur
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ns and followed by looping behavior. Inter-turn interval time of the zigzag turns increases significantly turn by turn. The programmed sequence of the movements is 'reset' and 'restarted' from the beginning in response to each pulsed pheromonal stimulation.
Pheromone-triggered brief excitation and a flipflopping neural activity pattern, whose response characteristics are similar to electric memory element (flipflop), generated in the microbrain and transmitted to a motor system in the thoracic ganglion play an important role for controlling the straight-line walking and the zigzag turns, respectively. Using such programmed behavior, and repeating the set and the reset of the program depending on the spatial and temporal distribution pattern of odors in the air, Bombyx males can orient toward the odor source without using complex memory and learning. Such behavioral strategies based on the neural mechanisms were evaluated by a small mobile robot, which had male moth antennae for detecting the pheromone. Less
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