| Budget Amount *help |
¥18,000,000 (Direct Cost: ¥18,000,000)
Fiscal Year 2001: ¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 2000: ¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1999: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Research Abstract |
1. The anterior median eye of the nocturnal spider Araneus showed a marked circadian oscillation of sensitivity, but that of the diurnal spider Menemerus showed no circadian oscillation. The anterior median eye of the noct/diurnal spider Argiope has two types of photoreceptor cells with different sensitivities. The more-sensitive cells showed a circadian oscillation of sensitivity, but the less-sensitive cells did not. The circadian sensitivity change of the eyes was controlled by efferent neurosecretory fibers in the optic nerve.
2. Illuminating the brain of the orb-weaving spider Argiope increased the frequency of efferent impulses in the optic nerve. Even if a large part of the brain is removed from the isolated brain-optic nerve preparation, but so as to leave the first- and second-order optic lobes intact, the frequency of efferent optic nerve impulses increased by illumination of the optic lobes. It seemed that the cerebral photosensitive neurons may be different from the efferent neurosecretory cells. The response of the cerebral photosensitive neurons increased transiently following diminution of the light intensity striking the eyes. The interaction between the cerebral photosensitive neurons and the eyes seemed to play a role in increasing this response.
3. Color discrimination in the jumping spider Hasarius was examined by heat-avoidance learning in association with colored papers. Spiders could learn to discriminate blue-green, blue-yellow, blue-red, blue-gray, green-yellow, green-red, green-gray, yellow-red, yellow-gray and red-gray patterns. Moreover, Spiders trained with a blue-white pattern, a green-white pattern, a yellow-white pattern or a red-white pattern could discriminate the blue, green, yellow or red from black.. It seems that jumping spiders can discriminate the blue, green, yellow and red papers by their hue.
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