The mediodorsal thalamus (MD) is a higher-order nucleus located within the central thalamus in many mammalian species. Emerging evidence from MD lesions and tracer injections suggests that the MD is reciprocally connected to the prefrontal cortex (PFC) and plays an essential role in specific cognitive processes and tasks. MD subdivisions (medial, central, and lateral) are poorly segregated at the molecular level in rodents, leading to a lack of MD subdivision-specific Cre driver mice. Moreover, this lack of molecular identifiers hinders MD subdivision- and cell-type-specific circuit formation and function analysis. Therefore, using publicly available databases, we explored molecules separately expressed in MD subdivisions. In addition to MD subdivision markers, we identified several genes expressed in a subdivision-specific combination and classified them. Furthermore, after developing medial MD (MDm) or central MD (MDc) region-specific Cre mouse lines, we identified diverse region- and layer-specific PFC projection patterns. Comparison between classified MD marker genes in mice and common marmosets, a nonhuman primate model, revealed diverging gene expression patterns. These results highlight the species-specific organization of cell types and their projections in the MD thalamus.

中文翻译：

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幼鼠和狨猴背内侧丘脑的分子细胞特性

内侧丘脑 (MD) 是位于许多哺乳动物物种的中央丘脑内的高级核。来自 MD 病变和示踪剂注射的新证据表明，MD 与前额叶皮层 (PFC) 相互关联，并在特定的认知过程和任务中发挥重要作用。MD 细分（内侧、中央和外侧）在啮齿动物的分子水平上分离不佳，导致缺乏 MD 细分特异性Cre司机老鼠。此外，分子标识符的缺乏阻碍了 MD 细分和细胞类型特定的电路形成和功能分析。因此，使用公开可用的数据库，我们探索了在 MD 细分中分别表达的分子。除了 MD 细分标记外，我们还确定了几个以细分特定组合表达的基因并对它们进行了分类。此外，在开发内侧 MD (MDm) 或中央 MD (MDc) 区域特异性Cre后鼠标线，我们确定了不同的区域和层特定的 PFC 投影模式。小鼠和普通狨猴（一种非人灵长类动物模型）中分类的 MD 标记基因之间的比较揭示了不同的基因表达模式。这些结果突出了细胞类型的物种特异性组织及其在 MD 丘脑中的投射。