School of Psychology, Cardiff University, Wales, CF10 3AT, United Kingdom.
Hippocampus. 2009 Nov;19(11):1090-102. doi: 10.1002/hipo.20574.
The medial diencephalon is vital for memory, but it is not known why. The present study tested between the predictions of current hypotheses as to why this region is critical for memory. Lesions were made in the rat mammillothalamic tract, the only diencephalic structure consistently associated with amnesia in humans after ischemia. Decreased activity, as measured by immediate-early gene expression (c-fos), was found in three key sites associated with memory function: the hippocampus, the prefrontal cortex, and the retrosplenial cortex. The specificity of these changes was confirmed by the qualitatively different patterns of immediately-early gene changes seen after amygdala lesions, e.g., hypoactivity in the hippocampus and retrosplenial cortex following mammillothalamic tract lesions but not following amygdala lesions. The mammillothalamic lesion results unify substrates linked to diencephalic and temporal lobe amnesia, and thereby support a new account of diencephalic amnesia that emphasizes multiple dysfunctions across hippocampal, retrosplenial, and prefrontal areas. This account suggests a role for the mammillary bodies that is independent of their hippocampal inputs.
内侧丘脑对于记忆至关重要，但尚不清楚原因。本研究在目前关于该区域对记忆至关重要的假设之间进行了检验。在大鼠乳头丘脑束中制造病变，这是人类缺血后与遗忘症一致相关的唯一间脑结构。通过即刻早期基因表达（c-fos）测量，在与记忆功能相关的三个关键部位发现了活性降低：海马体、前额叶皮质和后扣带皮质。杏仁核损伤后即刻早期基因变化的定性不同模式证实了这些变化的特异性，例如，乳头丘脑束损伤后海马体和后扣带皮质的活动减少，但杏仁核损伤后则没有。乳头丘脑束损伤的结果统一了与间脑和颞叶遗忘相关的底物，并支持强调海马体、后扣带和前额叶区域多个功能障碍的新的间脑遗忘症解释。该解释表明了乳状体的作用与其海马体输入无关。
