China creates 3D atlas of lamprey brain at single-cell level — ECNS
Scientists in China have created the first three-dimensional atlas of the entire lamprey brain at the level of individual cells. The study provides new information about how the brains of vertebrates evolved over hundreds of millions of years, ECNS reports.
The work was led by Su Bin of the Kunming Institute of Zoology at the Chinese Academy of Sciences, with the participation of researchers from BGI Research and Liaoning Normal University. In June, the study was published as a cover article in the scientific journal Science.
Molecular map of the brain
The atlas contains a highly detailed molecular map showing the locations of individual cells in the lamprey brain and the genes active in them. Lampreys are among the few living jawless vertebrates. According to the fossil record, their basic body structure has not changed significantly for approximately 360 million years, making these animals important for reconstructing the brains of vertebrate ancestors.
A comparison of the lamprey brain atlas with a mouse atlas revealed similarities in gene expression patterns and functions in several brain regions. According to Su Bin, this may indicate that the common ancestor of vertebrates already had a well-organized and molecularly complex brain.
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Neuron specialization
The scientists also compared genomic and molecular data from lampreys with data from zebrafish, turtles, lizards, zebra finches, pigeons, mice and macaques. They studied how neurons became more narrowly specialized over time.
Particular attention was paid to AEN neurons, which are common in lampreys and zebrafish. They have molecular markers associated with both excitatory and inhibitory signaling and may perform several functions. Such cells are less common in amniotes, where specialized neurons predominate instead. The researchers found that the emergence of such specialized neurons coincided with an ancient second whole-genome duplication in the common ancestor of jawed vertebrates.
In addition, cells molecularly similar to zebrafish cerebellar interneurons were found in a lamprey brain region resembling the cerebellum. This indicates that a primitive form of the cerebellum may already have existed in early vertebrates. Su Bin also noted that understanding the evolution of the human brain could potentially be useful for developing artificial intelligence software and hardware.
