Operation System of Insect Brain for Sophisticated Behavior

虎甲虫（Cicindela chinensis）的幼虫是一种埋伏猎手，体长15-22毫米，生活在地下的隧道中。它伏击猎物，在隧道开口处保持头部水平。当猎物接近隧道时，幼虫跳起来咬住它。然而，当物体移动超过其跳跃范围（约15毫米）时，幼虫迅速退回到隧道深处。这些反应是由6对茎干中的2对介导的。幼虫是如何用这么简单的视觉系统来判断狩猎范围的呢？通过行为观察证实了双眼视觉对距离的估计。在行为观察中，当通过棱镜或窄窗在幼虫附近形成这些遥远物体的虚拟图像时，幼虫会跳向正常狩猎范围以外的物体。通过行为实验验证了单目视觉距离估计的正确性。视网膜图像的深度似乎在距离估计中起着作用，因为当一个具有更多功能的茎干被遮挡时，当一个凹透镜放在它的头上时，它对很远的物体的反应从逃跑变成了跳跃。髓质神经元（二级视觉中间神经元）的细胞内反应表明，距离敏感确实发生在大脑的外周部分。比较了髓质神经元对高度为10 mm和50 mm的运动物体的反应模式。大多数神经元对高度为10毫米和50毫米的物体有相同的放电模式。然而，少数神经元表现出距离敏感性，只在两个高度中的任何一个高度对移动物体的峰值放电增加作出反应。这种距离敏感性在单茎幼虫中仍然存在，4个茎中有3个被遮挡。上述行为和电生理结果表明。我们认为，虎甲虫幼虫的狩猎范围的视觉信息是通过图像清晰度的空间模式在外围提取的，而可能是通过双眼视觉来集中提取的。少

The larva of the tiger beetle Cicindela chinensis is an ambushing hunter with a body length of 15-22 mm, that lives in a tunnel in the ground. It ambushes prey, keeping its head horizontal at the opening of the tunnel. When prey approaches the tunnel, the larva jumps to snap at it. When an object moves beyond its jumping range (approximately 15 mm), however, the larva quickly withdraws deep into the tunnel. These responses are mediated by two of six pairs of stemmata. How does the larva judge the hunting range using such a simple visual system? Range estimation by binocular vision was confirmed by behavioral observations, in which larvae jumped towards objects beyond the normal hunting range when virtual images of such distant objects were formed close to the larva by prisms or a narrow window. Range estimation by monocular vision was also confirmed by behavioral experiments. The depth of the image in the retina appears to have a role in distance estimation because a larva with one fun … More ctional stemma, other stemmata being occluded, changed its response to a very distant object from escape to jump when a concave lens was placed above its head.Intracellular responses of medulla neurons (second order visual interneurons) showed that distance sensitivities really occurred in the peripheral part of the brain. Response patterns of medulla neurons to moving objects at heights of 10 mm and 50 mm were compared. The majority of neurons responded to objects moving at heights of 10 mm and 50 mm with the same discharge pattern. A few neurons, however, showed distance sensitivities responding with an increase of spike discharges to moving objects only at either of the two heights. Such distance sensitivities still remained in one-stemma larvae, three of the four stemmata being occluded.Above mentioned behavioral and electrophysiological results suggested. We conclude that visual information about hunting range in the tiger beetle larva is extracted peripherally by the spatial pattern of image clarity, and probably centrally by binocular vision. Less