Behavioral and Histological study on the output resolution of orienting behavior of the frog.

<组织学研究结果>我们研究了与蛙的猎物定向行为相关的顶叶输出神经元的空间分布。神经生物素作为逆行示踪剂注射到nMLF和离体前嗅核中。切向切片用低温恒温器在40 μm处切割。计算空间自相关图，检验标记细胞分布的规律性。结果表明：1)标记的输出神经元根据胞体大小分为A型和B型两组，2)每组胞体在某些截面上聚集在一起，在另一些截面上单独存在，但所有胞体都表现出特有的周期性分布，3)A型神经元的周期分布在整个顶盖上表现出相同的间隔，而B型神经元的周期分布则表现出特定区域的间隔。<行为研究结果>我们计算了青蛙的转弯角度（θ1），蟋蟀在青蛙定向响应前的角度（θ2），定向响应误差（θ1 - θ2），定向时间，以及定向行为的角速度。青蛙定向转向的角速度在20度、40度和65度处逐渐增加。在角速度逐步变化的幅度处观察到取向误差的峰值。当青蛙错过猎物时，动物会增加转弯速度以成功捕获猎物。我们还发现，青蛙对蟋蟀在方向响应之前移动了很长一段距离的动作表现出了一个具有预定幅度的不准确的转向。该幅值与观测到的转弯速度逐级递增的幅值吻合较好。因此，对于这样一个困难的目标，他们可能会转向最近的预定位置，以节省能量。

<Results from histological study>We examined spatial distribution of tectal efferent neurons related to prey orienting behavior in the frog Rana catesbeiana. Neurobiotin was injected as retrograde tracer into the nMLF and the anterodorsal nucleus in vitro preparations. Tangential sections were cut at 40 μm with a cryostat. Spatial autocorrelogram was computed to examine the regularity of the distribution of labeled cells. The results showed that 1)the labeled output neurons are classified into two groups (type A and B) based on their cell body size, 2)in each group, cell bodies cluster together in some sections and stand alone in others, however, all of the cell bodies show characteristic periodical distribution, 3)periodical distribution of type A neurons shows the same interval throughout the tectum, while that of type B neurons shows the region-specific intervals.<Results from behavioral study>We calculated the turn angle of the frog (θ1), the angle of the cricket before orientation response of the frog (θ2), the error in orientation response (θ1 minusθ2), the amount of time for orientation, and the angular velocity of orienting behavior. Angular velocity of frog's orienting turn showed the step-by-step increment occurring at 20,40,and 65 degrees. The peaks of the error in orientation were observed at the amplitudes where the step-by-step change of angular velocity occurred. When the frog comes to miss the prey object, the animal increases the turning velocity to capture the prey successfully. We also found that the frog showed an inaccurate turn with predetermined amplitude to the cricket which moves a long distance before orientation response. The amplitude showed good agreement with those where the step-by-step increment of turn velocity was observed. Therefore, for such a difficult target, they may turn into the nearest predetermined position to save energy.