Elepfandt A
Fakultät Biologie, Universität Konstanz, BRD.
Brain Behav Evol. 1988;31(6):358-68. doi: 10.1159/000116601.
The organization of water wave localization within the midbrain of the clawed frog Xenopus was investigated by performing behavioral tests on frogs that had partial midbrain ablations. The criterion of localization was the orientation of turns toward the origin of impinging waves. All lesion effects became apparent as localization failure within an angular sector of wave direction. The sectors were contralateral to the lesion and of various sizes, some comprising the complete hemifield. Localization outside of the sectors was not affected. Thus, wave localization is topologically organized with respect to wave direction. Two topological projections were found. Lesions of the first projection resulted in unoriented responses to the affected wave directions. After lesions of the other projection, the frog responded to waves from the affected directions by lunges without turns. It is suggested that the two types of localization failures are due to impairment of the sensory wave direction detection and of the sensorimotor transfer, respectively. The essential midbrain areas are presumably the magnocellular nucleus of the torus magnocellularis and the ventrolateral tectum, but a considerable part of the localization might be done in the medulla.
通过对部分中脑切除的非洲爪蟾进行行为测试，研究了水波在其大脑中脑内的定位组织。定位的标准是转向撞击波源的转动方向。所有损伤效应都表现为在波方向的一个角扇区内定位失败。这些扇区与损伤对侧，大小各异，有些包括整个半视野。扇区外的定位不受影响。因此，水波定位在拓扑结构上是按照波的方向组织的。发现了两种拓扑投影。第一种投影的损伤导致对受影响波方向的无定向反应。另一种投影损伤后，青蛙对来自受影响方向的波通过猛冲而不转动来做出反应。有人认为，这两种定位失败类型分别是由于感觉波方向检测和感觉运动传递受损所致。关键的中脑区域大概是大细胞环核和腹外侧顶盖，但相当一部分定位可能在延髓中完成。
