Department of Cell Biology, Faculty of Biological Sciences, Complutense University, 28040, Madrid, Spain.
Sci Rep. 2024 Apr 5;14(1):7999. doi: 10.1038/s41598-024-58671-x.
The study of the brain by magnetic resonance imaging (MRI) in evolutionary analyses is still in its incipient stage, however, it is particularly useful as it allows us to analyze detailed anatomical images and compare brains of rare or otherwise inaccessible species, evolutionarily contextualizing possible differences, while at the same time being non-invasive. A good example is the lungfishes, sarcopterygians that are the closest living relatives of tetrapods and thus have an interesting phylogenetic position in the evolutionary conquest of the terrestrial environment. In the present study, we have developed a three-dimensional representation of the brain of the lungfish Protopterus annectens together with a rostrocaudal anatomical atlas. This methodological approach provides a clear delineation of the major brain subdivisions of this model and allows to measure both brain and ventricular volumes. Our results confirm that lungfish show neuroanatomical patterns reminiscent of those of extant basal sarcopterygians, with an evaginated telencephalon, and distinctive characters like a small optic tectum. These and additional characters uncover lungfish as a remarkable model to understand the origins of tetrapod diversity, indicating that their brain may contain significant clues to the characters of the brain of ancestral tetrapods.
磁共振成像（MRI）在进化分析中对大脑的研究仍处于起步阶段，但它特别有用，因为它允许我们分析详细的解剖图像，并比较罕见或其他难以获得的物种的大脑，从进化的角度来解释可能存在的差异，同时又非侵入性。一个很好的例子是肺鱼，肉鳍鱼类是四足动物最接近的现存亲属，因此在进化过程中对陆地环境的征服中具有有趣的系统发育地位。在本研究中，我们已经开发了肺鱼 Protopterus annectens 的大脑的三维表示以及一个前后解剖图谱。这种方法为该模型的主要大脑分区提供了清晰的界定，并允许测量大脑和脑室的体积。我们的结果证实，肺鱼表现出与现存的基底肉鳍鱼类相似的神经解剖模式，具有外突的端脑和独特的特征，如小的视顶盖。这些和其他特征表明肺鱼是一个理解四足动物多样性起源的显著模型，表明它们的大脑可能包含对祖先四足动物大脑特征的重要线索。
