Neave N, Nagle S, Aggleton J P
Division of Psychology, University of Northumbria at Newcastle, UK.
Eur J Neurosci. 1997 May;9(5):941-55. doi: 10.1111/j.1460-9568.1997.tb01445.x.
Comparisons were made between the behavioural effects of lesions in three inter-related limbic structures: the mammillary bodies, the fornix and the cingulum bundle/cingulate cortex. Cytotoxic lesions of the mammillary nuclei produced a marked deficit on reinforced T-maze alternation, but performance gradually improved with practice. Subsequent tests in a cross-maze and a radial-arm maze showed that the animals with mammillary body lesions failed to use allocentric cues, but were able to perform normally in an egocentric discrimination. Three groups of rats with different patterns of either crossed or unilateral radio frequency lesions of the cingulate region were given the same tasks. The profile of results indicated that disruption of those fibres in the cingulum bundle connecting the anterior thalamic nuclei with the hippocampal/retrohippocampal region was responsible for the observed impairments to T-maze alternation and radial-arm maze performance. There was also evidence that disconnection of frontal connections in the cingulum bundle might affect perseverative behaviour, but not allocentric processing. The results add support to the notion of a functional circuit that involves projections from the hippocampus to the mammillary bodies and anterior thalamic nuclei, and from there back to hippocampal/retrohippocampal regions via the cingulum bundle. This circuit appears to be vital for normal allocentric processing.
乳头体、穹窿和扣带束/扣带回皮质。乳头体核的细胞毒性损伤在强化T迷宫交替任务中产生了明显的缺陷，但随着训练，表现逐渐改善。随后在十字迷宫和放射状臂迷宫中的测试表明，乳头体损伤的动物无法利用空间线索，但能够在自我中心辨别任务中正常表现。对三组扣带回区域有不同交叉或单侧射频损伤模式的大鼠进行了相同的任务测试。结果表明，扣带束中连接丘脑前核与海马/海马后区域的纤维中断是导致观察到的T迷宫交替和放射状臂迷宫表现受损的原因。也有证据表明，扣带束中额叶连接的中断可能会影响持续性行为，但不会影响空间处理。这些结果支持了一个功能回路的概念，该回路涉及从海马到乳头体和丘脑前核的投射，并从那里通过扣带束回到海马/海马后区域。这个回路似乎对正常的空间处理至关重要。
