Neural mechanisms for multi-sensory selection of behavior in microbrain system.

<Behavioral Analyses>昆虫能够感知环境中的湿度梯度，并偏好一定湿度的区域。分析了美洲大蠊的湿度定位行为。将昆虫放入具有湿度梯度的竞技场中，沿着竞技场外围运行后，昆虫停留在湿度较高的部分。这种行为是由于1）无空间运动的行为增加，2）步行速度降低，3）在高湿度区域比低湿度区域的弯曲度（deg/cm）增加。该虫到达水的行为序列包括1）发现水后停止移动，2）以站立姿势移动触角和颈部以寻找湿度梯度，3）向湿度较高的区域行走。<Physiological and Morphological Analyses>应用细胞内记录和染色方法，鉴定了美洲大蠊中脑对湿度和温度反应的投射神经元。我们已经表明，水感受器和热感受器神经元分别终止于触角叶的特定肾小球复合体。在本研究中，我们发现中脑投射神经元的树突支配这些复合体和它们的轴突都支配蘑菇体和侧叶的前脑。此外，在侧叶，湿反应投射神经元和热感受投射神经元的轴突终末面积也不同。这表明在外侧叶中存在功能分离。

<Behavioral Analyses>The insects can detect humidity gradient in their environment and prefer area of certain humidity. We analyzed the humidity-location behavior of the cockroach, Periplaneta americana. The insect put into the arena, in which there was humidity gradient, stayed in higher humidity part after it had run along the periphery of the arena. This behavior was resulted from 1) the behavior without spatial movement was increased, 2) the walking velocity was decreased, and 3) the meander (deg/cm) was increased in higher humid area than in lower humid area. The behavioral sequence for the insect to reach water consisted of 1) stopping to move after detection of water, 2) moving its antennae and neck to search humidity gradient in the standing posture, and 3) walking toward higher humidity area.<Physiological and Morphological Analyses>The deutocerebral projection neurons responsive to humidity or temperature were identified in Periplaneta americana, using intracellular recording and staining methods. We have already showed that the hygro- and themoreceptor neurons terminate in specific glomerular complexes in the antennal lobe, respectively. In this study we found that dendrites of the deutocerebral projection neurons innervated into these complexes and their axons innervated both into the mushroom body and the lateral lobe of protocerebrum. Furthermore axonal terminal areas in the lateral lobe were different between the hygro-responsive projection neurons and thermoreceptive projection neurons. This shows that there are functional segregations in the lateral lobe.