Nuclear Medicine and Molecular Imaging Division, Diagnostic Department, University Hospitals of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211, 14, Genève, Switzerland.
Faculty of Medicine, Geneva University, 1211, Geneva, Switzerland.
Mol Imaging Biol. 2020 Apr;22(2):417-424. doi: 10.1007/s11307-019-01377-8.
The parcellation of the thalamus into different nuclei involved in different corticothalamocortical loops reflects its functional diversity. The connections between the mediodorsal nucleus and the prefrontal cortex play a major role in cognition, particularly in the rapid processing of behaviorally relevant information. The thalamus is the brain region with the highest density in α4β2 nicotinic acetylcholine receptors, the main human nicotinic acetylcholine receptor subtype. The aim of this study was to investigate the possible role of the nicotinic cholinergic system in the thalamo-cortical loops measuring receptor density in different subregions of the thalamus, based on their cortical connectivity.
We studied α4β2 nicotinic acetylcholine receptors using positron emission tomography and [F]Fluoro-A-85380, a radiotracer specific for this receptor subtype, in 36 non-smoking male subjects, including 12 healthy controls and 24 patients with epilepsy. [F]Fluoro-A-85380 ratio index of binding potential was compared by a repeated measures general linear model, including the thalamic subregions and the brain hemisphere as within-subject factor and clinical groups as between-subject factor.
The "prefrontal" thalamus, the subregion including the mediodorsal nucleus, had a significantly higher nicotinic acetylcholine receptor density than all other thalamic subregions. These findings were confirmed when analyzing solely the 12 healthy controls.
This particular neurochemical organization of the thalamus supports a major role of the cholinergic system in the loops between the thalamus and the prefrontal cortex. The highest nicotinic acetylcholine receptor density in the « higher-order thalamus » could partly explain the beneficial effect of acute nicotine on attentional and executive functions and possibly the pathophysiology of some neuropsychiatric disorders.
丘脑被划分为不同的核团，这些核团参与不同的皮质-丘脑-皮质回路，反映了其功能的多样性。背内侧核与前额叶皮层之间的连接在认知中起着重要作用，特别是在快速处理与行为相关的信息方面。丘脑是大脑中α4β2 烟碱型乙酰胆碱受体密度最高的区域，α4β2 烟碱型乙酰胆碱受体是人类主要的烟碱型乙酰胆碱受体亚型。本研究旨在通过测量基于皮质连接的不同丘脑亚区的受体密度，探讨烟碱胆碱能系统在丘脑-皮质回路中的可能作用。
我们使用正电子发射断层扫描和 [F]氟烷-A-85380（一种针对该受体亚型的放射性示踪剂）研究了 36 名不吸烟的男性受试者中的 α4β2 烟碱型乙酰胆碱受体，包括 12 名健康对照者和 24 名癫痫患者。采用重复测量一般线性模型比较 [F]氟烷-A-85380 结合潜能比指数，包括丘脑亚区和大脑半球作为受试者内因素，临床组作为受试者间因素。
“前额叶”丘脑，包括背内侧核的亚区，其烟碱型乙酰胆碱受体密度明显高于所有其他丘脑亚区。当仅分析 12 名健康对照者时，也得到了相同的结果。
丘脑的这种特殊神经化学组织支持胆碱能系统在丘脑与前额叶皮层之间的回路中发挥主要作用。“高级丘脑”中最高的烟碱型乙酰胆碱受体密度部分解释了急性尼古丁对注意力和执行功能的有益影响，以及可能的一些神经精神疾病的病理生理学。
