Commons Kathryn G
Department of Anesthesiology, Perioperative, and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts 02115; Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, 02115.
J Comp Neurol. 2015 Jul 1;523(10):1488-504. doi: 10.1002/cne.23748. Epub 2015 Mar 16.
Serotonin neurons in the dorsal and median raphe nuclei (DR and MR) are clustered into heterogeneous groups that give rise to topographically organized forebrain projections. However, a compelling definition of the key subgroups of serotonin neurons within these areas has remained elusive. In order to be functionally distinct, neurons must participate in distinct networks. Therefore, we analyzed subregions of the DR and MR by their afferent input. Clustering methods and principal component analysis were applied in mouse to anterograde tract-tracing experiments available from the Allen Mouse Brain Connectivity Atlas. The results revealed a major break in the networks of the DR such that the caudal third of the DR was more similar in afferent innervation to the MR than it was to the rostral two-thirds of the DR. The rostral part of the DR is associated with networks controlling motor and motivated behavior, while the caudal DR is more closely aligned with regions that regulate rhythmic hippocampal activity. Thus, a major source of heterogeneity within the DR is inclusion of the caudal component, which may be more accurately viewed as a dorsal extension of the MR.
中缝背核和中缝正中核（DR和MR）中的5-羟色胺能神经元聚集成不同的群体，这些群体产生了具有拓扑结构的前脑投射。然而，这些区域内5-羟色胺能神经元关键亚群的令人信服的定义仍然难以捉摸。为了在功能上有所不同，神经元必须参与不同的网络。因此，我们根据传入输入对DR和MR的亚区域进行了分析。聚类方法和主成分分析应用于小鼠的顺行束追踪实验，这些实验数据来自艾伦小鼠脑连接图谱。结果显示DR网络存在一个主要断点，即DR的尾三分之一在传入神经支配方面与MR比与DR的头三分之二更相似。DR的头侧部分与控制运动和动机行为的网络相关，而尾侧DR与调节海马节律性活动的区域更紧密相关。因此，DR内异质性的一个主要来源是包含尾侧部分，这部分可能更准确地被视为MR的背侧延伸。
