Petrosini L, Leggio M G, Molinari M
Department of Psychology, University of Rome La Sapienza, Italy.
Prog Neurobiol. 1998 Oct;56(2):191-210. doi: 10.1016/s0301-0082(98)00036-7.
The experimental findings reviewed here indicate that the cerebellum has to be added to the regions known to be involved in the spatial learning. Cerebellar function is specifically linked to 'how to find an object' rather than 'where the object is in the space'. In the Morris water maze (MWM) hemicerebellectomized (HCbed) rats displayed a severe impairment in coping with spatial information, displaying only peripheral circling. And yet, when the MWM cue phase was prolonged, HCbed rats succeeded in acquiring some abilities to learn platform position, even in a pure place paradigm, such as finding a hidden platform with the starting points sequentially changed. Conversely, whether the searching strategy was acquired preoperatively, no exploration deficit appeared. Thus, cerebellar lesions appear to affect the procedural components of spatial function, sparing the declarative ones. When intact animals were non-spatially pre-trained and then HCbed, they exhibited an expanded scanning strategy, underlining the cerebellar involvement in procedural component acquisition. By testing HCbed rats in an active avoidance task, first without and then with a request for right/left discrimination, lesioned rats displayed severe deficits. Thus, besides a marked impairment in facing procedural components of spatial processing, cerebellar lesion provokes deficits also in right/left discrimination task. In conclusion, it is possible to propose the cerebellum as one part of a large system that includes frontal, posterior parietal, inferior temporal cortices, hippocampus and basal ganglia. These structures form an allocentric spatial system and an egocentric control system, that interlock to process the information involved in representing an object in the space.
此处回顾的实验结果表明，小脑必须被纳入已知参与空间学习的区域之中。小脑功能具体与“如何找到物体”相关，而非“物体在空间中的位置”。在莫里斯水迷宫（MWM）实验中，半侧小脑切除（HCbed）的大鼠在处理空间信息方面表现出严重受损，仅表现出外周转圈行为。然而，当MWM提示阶段延长时，HCbed大鼠即使在纯位置范式下，比如在起始点依次改变的情况下找到隐藏平台，也成功获得了一些学习平台位置的能力。相反，无论术前是否习得搜索策略，均未出现探索缺陷。因此，小脑损伤似乎影响空间功能的程序组件，而不影响陈述性组件。当完整动物进行非空间预训练后再进行HCbed手术时，它们表现出扩展的扫描策略，这突出了小脑在程序组件习得中的作用。通过在主动回避任务中测试HCbed大鼠，先是不进行左右辨别要求，然后提出左右辨别要求，发现损伤大鼠表现出严重缺陷。因此，除了在面对空间处理的程序组件方面存在明显损伤外，小脑损伤在左右辨别任务中也会引发缺陷。总之，可以提出小脑是一个大系统的一部分，该系统包括额叶、顶叶后部、颞下皮质、海马体和基底神经节。这些结构形成一个以空间为中心的空间系统和一个以自我为中心的控制系统，它们相互关联以处理与在空间中表征物体相关的信息。
