Hunt P R, Aggleton J P
M.R.C. Cambridge Centre for Brain Repair, University of Cambridge, UK.
Behav Brain Res. 1998 Dec;97(1-2):129-41. doi: 10.1016/s0166-4328(98)00033-3.
The present study examined the performance of rats with neurotoxic lesions centred in the thalamic nucleus medialis dorsalis on standard and modified versions of the eight arm radial maze test. In Experiment 1, the thalamic lesions produced a borderline deficit in acquisition of the standard task, but subsequently had no effect when a delay was interposed after the first four arms had been entered. The same lesions had no effect on T-maze alternation, but they did impair radial-arm maze performance when intramaze and extramaze cues were set against each other. In Experiment 2, lesions of the dorsomedial thalamus impaired acquisition of the standard radial-arm maze task, but combining the results from Experiments 1 and 2 showed that this acquisition deficit was confined to those animals in which bilateral damage extended into the adjacent anterior thalamic nuclei. In addition, lesions of the dorsomedial thalamus disrupted radial-arm maze performance when the task was modified to compare working memory and reference memory and increased activity and exploration. These changes were not associated with anterior thalamic damage. Finally, the thalamic lesions did not affect performance on a test of spontaneous object recognition. It is concluded that lesions of medialis dorsalis do not disrupt spatial memory but do affect other processes that can interact with task performance. These include a failure of extramaze cues to overshadow intramaze cues, a change in activity and exploration levels and deficits in with-holding spatial responses.
本研究考察了以背内侧丘脑核为中心发生神经毒性损伤的大鼠在标准八臂放射状迷宫测试及改良版测试中的表现。在实验1中，丘脑损伤在标准任务的习得过程中产生了临界缺陷，但在进入前四条臂之后设置延迟时，随后并未产生影响。相同的损伤对T迷宫交替没有影响，但当迷宫内外线索相互对立时，它们确实损害了放射状迷宫的表现。在实验2中，背内侧丘脑损伤损害了标准放射状迷宫任务的习得，但将实验1和实验2的结果结合起来表明，这种习得缺陷仅限于双侧损伤延伸至相邻前丘脑核的动物。此外，当任务被修改以比较工作记忆和参考记忆以及增加活动和探索时，背内侧丘脑损伤破坏了放射状迷宫的表现。这些变化与前丘脑损伤无关。最后，丘脑损伤不影响自发物体识别测试的表现。得出的结论是，背内侧损伤不会破坏空间记忆，但会影响其他可能与任务表现相互作用的过程。这些包括迷宫外线索无法掩盖迷宫内线索、活动和探索水平的变化以及抑制空间反应的缺陷。
