Department of Psychology, University of Canterbury, Christchurch, New Zealand.
Brain Research New Zealand, co-hosted by Auckland and Otago Universities, Auckland, New Zealand.
Hippocampus. 2018 Feb;28(2):121-135. doi: 10.1002/hipo.22815. Epub 2017 Nov 29.
The anterior thalamic nuclei (ATN), mammillary bodies and their interconnecting fiber tract, the mammillothalamic tract (MTT), are important components of an extended hippocampal circuit for episodic memory. In humans, damage to the MTT or ATN in many disorders is associated with severe anterograde amnesia and it is assumed that their influence on memory is functionally equivalent. The relative influence of these two structures on memory has not, however, been assessed explicitly. Here, a direct comparison found that only ATN lesions impaired spatial reference memory in rats. ATN lesions produced more severe deficits on spatial working memory and reduced zif268 expression to a greater degree and in more corticolimbic sites than did MTT lesions. Conversely, MTT lesions reduced NeuN cell counts in all three subregions of the MB to a greater extent than did ATN lesions, so their relative impact cannot be explained by retrograde neuropathology of the MB. Hence ATN injury causes a more critical dysfunction than would be expected by an emphasis on the indirect influence of brainstem inputs to the extended memory system. The greater ATN lesion deficits found here may represent the consequence of disruption to the direct connections of the ATN with both hippocampal and cortical sites.
前丘脑核（ATN）、乳头体及其连接的纤维束——乳头体丘脑束（MTT），是扩展的海马体回路中形成情景记忆的重要组成部分。在人类中，MTT 或 ATN 的损伤与严重的顺行性遗忘有关，并且假设它们对记忆的影响在功能上是等效的。然而，这两种结构对记忆的相对影响尚未被明确评估。在这里，一项直接比较发现，只有 ATN 损伤会损害大鼠的空间参考记忆。ATN 损伤导致空间工作记忆的损伤更为严重，并且在皮质边缘区的更多部位，zif268 的表达减少程度比 MTT 损伤更为严重。相反，MTT 损伤导致 MB 的所有三个亚区的 NeuN 细胞计数减少程度大于 ATN 损伤，因此它们的相对影响不能用 MB 的逆行神经病理学来解释。因此，ATN 损伤导致的功能障碍比仅仅强调脑干输入对扩展记忆系统的间接影响所预期的更为严重。这里发现的 ATN 损伤更大的缺陷可能代表了 ATN 与海马体和皮质部位的直接连接中断的后果。
