Researchers decode patterns that make our brains human
Despite the anatomical complexity of the brain and the complexity of the human genome, most of the patterns of gene usage across all 20,000 genes could be characterized by just 32 expression patterns. While many of these patterns were similar in human and mouse, the dominant genetic model organism for biomedical research, many genes showed different patterns in human. Surprisingly, genes associated with neurons were most conserved across species, while those for the supporting glial cells showed larger differences.
“The human brain is phenomenally complex, so it is quite surprising that a small number of patterns can explain most of the gene variability across the brain,” says Christof Koch, Ph.D., President and Chief Scientific Officer at the Allen Institute for Brain Science. “There could easily have been thousands of patterns, or none at all. This gives us an exciting way to look further at the functional activity that underlies the uniquely human brain.” More.
So few patterns, one wonders why more life forms didn’t hit on it? Maybe there is more to know.
Here’s the abstract:
The structure and function of the human brain are highly stereotyped, implying a conserved molecular program responsible for its development, cellular structure and function. We applied a correlation-based metric called differential stability to assess reproducibility of gene expression patterning across 132 structures in six individual brains, revealing mesoscale genetic organization. The genes with the highest differential stability are highly biologically relevant, with enrichment for brain-related annotations, disease associations, drug targets and literature citations. Using genes with high differential stability, we identified 32 anatomically diverse and reproducible gene expression signatures, which represent distinct cell types, intracellular components and/or associations with neurodevelopmental and neurodegenerative disorders. Genes in neuron-associated compared to non-neuronal networks showed higher preservation between human and mouse; however, many diversely patterned genes displayed marked shifts in regulation between species. Finally, highly consistent transcriptional architecture in neocortex is correlated with resting state functional connectivity, suggesting a link between conserved gene expression and functionally relevant circuitry. (paywall) – Michael Hawrylycz, Jeremy A Miller, Vilas Menon, David Feng, Tim Dolbeare, Angela L Guillozet-Bongaarts, Anil G Jegga, Bruce J Aronow, Chang-Kyu Lee, Amy Bernard, Matthew F Glasser, Donna L Dierker, Jörg Menche, Aaron Szafer, Forrest Collman, Pascal Grange, Kenneth A Berman, Stefan Mihalas, Zizhen Yao, Lance Stewart, Albert-László Barabási, Jay Schulkin, John Phillips, Lydia Ng, Chinh Dang, David R Haynor, Allan Jones, David C Van Essen, Christof Koch, Ed Lein. Canonical genetic signatures of the adult human brain. Nature Neuroscience, 2015; DOI: 10.1038/nn.4171
See also: Neuroscience tried wholly embracing naturalism, but then the brain got away
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