Elepfandt A
Fakultät Biologie, Universität Konstanz, BRD.
Brain Behav Evol. 1988;31(6):349-57. doi: 10.1159/000116600.
The central nervous organization of water wave localization in the clawed frog Xenopus laevis was investigated by performing behavioral tests on frogs that had various brain ablations. The criterion of localization was the orientation of response turns toward the origin of stimulus waves. After complete midbrain ablation, Xenopus still detected impinging waves but could not localize them. After thalamopretectal ablation, however, Xenopus localized waves with normal accuracy. Thus, wave localization can be accomplished in the brainstem, and the midbrain is necessary for it. After forebrain ablation, the frogs no longer responded to water waves, which shows that higher brain centers modulate localization. Tectal lesions that spared the ventrolateral tectum did not abolish localization. After unilateral extirpation of tectum and torus, all ipsilateral waves were localized, but contralateral waves were not. This indicates a functional chiasm for the determination of wave directions in the midbrain. Total localization failure after unilateral midbrain destruction demonstrates that wave localization also requires the ipsilateral motorial tegmentum. When wave localization was abolished, a residual correlation between stimulus directions and response angles remained.
通过对进行了各种脑部切除的非洲爪蟾进行行为测试，研究了其水波定位的中枢神经组织。定位的标准是反应转向刺激波源的方向。在完全切除中脑后，非洲爪蟾仍能检测到撞击波，但无法对其进行定位。然而，在切除丘脑前顶盖后，非洲爪蟾能以正常精度定位水波。因此，水波定位可在脑干中完成，而中脑对此是必需的。切除前脑后，青蛙不再对水波做出反应，这表明更高的脑中枢调节定位。保留腹外侧顶盖的顶盖损伤并未消除定位。在单侧切除顶盖和丘脑后结节后，所有同侧波都能被定位，但对侧波则不能。这表明在中脑存在一个用于确定波方向的功能性交叉。单侧中脑破坏后完全丧失定位能力表明，水波定位还需要同侧运动被盖。当水波定位被消除时，刺激方向与反应角度之间仍存在残余相关性。
