Mooney R D, Klein B G, Rhoades R W
Neuroscience. 1987 Feb;20(2):537-55. doi: 10.1016/0306-4522(87)90109-6.
The right superior colliculus and right eye were ablated in hamsters within 12 h of birth and the visual and somatosensory representations in the remaining (left) superior colliculus were evaluated using standard single unit recording and receptive field mapping techniques when the animals reached adulthood (at least 3 months of age). In a number of the hamsters used for recording, injections of [3H]leucine were made into the left eye 6-10 days prior to the terminal experiment. This was done to insure that the neonatal lesions did, in fact, produce the extensive recrossing of retinal fibers demonstrated by others who have employed this preparation. All of the hamsters which received [3H]leucine injections prior to the recording experiment exhibited a markedly expanded ipsilateral retinocollicular projection and retinal axons which recrossed the midline at the level of the tectum. The recording experiments showed further that this projection resulted in a visual map which was generally mirror symmetric to that in normal hamsters. There were, however, numerous irregularities and discontinuities in this representation and, in a few hamsters, it appeared almost completely disorganized. There were also a number of abnormalities in the somatosensory representation in the deep tectal laminae of the neonatally brain damaged hamsters. There was a substantial increase in the number of cells with receptive fields that extended onto the ipsilateral side of the body, neurons with split receptive fields were recorded and there were changes in the magnification of different portions of the body surface. These alterations did not, however, change the organization of the somatosensory map in a manner which brought it into alignment with the visual representation in the superficial laminae. Nevertheless, additional recording experiments in animals subjected to enucleation of both eyes and ablation of the superficial laminae of one superior colliculus did indicate that the existence of the aberrant retinal projection was a necessary condition for the somatosensory abnormalities which we observed. Additional anterograde and retrograde tracing experiments demonstrated only one abnormality in the organization of the somatosensory afferent input to the remaining colliculus. In 75% of the brain damaged hamsters, there was a weak crossed projection from the sensorimotor cortex that was never observed in normal animals. Ablation of this cortex at the time of the recording experiment did not, however, reduce the incidence of abnormal somatosensory receptive fields in these hamsters.
在仓鼠出生后12小时内切除其右上丘和右眼，当动物成年（至少3个月大）时，使用标准的单单位记录和感受野映射技术评估剩余（左）上丘中的视觉和体感表征。在一些用于记录的仓鼠中，在终末实验前6 - 10天向左眼注射[3H]亮氨酸。这样做是为了确保新生期损伤确实如其他采用该制备方法的人所证明的那样，导致视网膜纤维广泛重新交叉。在记录实验前接受[3H]亮氨酸注射的所有仓鼠都表现出同侧视网膜 - 上丘投射明显扩大，并且视网膜轴突在顶盖水平重新交叉中线。记录实验进一步表明，这种投射产生了一个视觉图谱，它通常与正常仓鼠的视觉图谱呈镜像对称。然而，在这个表征中有许多不规则和不连续之处，并且在一些仓鼠中，它几乎看起来完全紊乱。在新生期脑损伤的仓鼠的深层顶盖板层中，体感表征也存在一些异常。感受野延伸到身体同侧的细胞数量大幅增加，记录到了具有分裂感受野的神经元，并且身体表面不同部分的放大倍数发生了变化。然而，这些改变并没有以使其与浅层板层中的视觉表征对齐的方式改变体感图谱的组织。尽管如此，对双眼摘除和一个上丘浅层板层切除的动物进行的额外记录实验确实表明，异常视网膜投射的存在是我们观察到的体感异常的必要条件。额外的顺行和逆行追踪实验仅证明了体感传入输入到剩余上丘的组织中存在一种异常。在75%的脑损伤仓鼠中，存在来自感觉运动皮层的微弱交叉投射，这在正常动物中从未观察到。然而，在记录实验时切除该皮层并没有降低这些仓鼠中异常体感感受野的发生率。
