In a paper published this week in the journal Frontiers of Physics, a duo of researchers from Italy investigated the similarities between the network of neurons in the human brain and the cosmic network of galaxies.
Top: neurons and glial cells. Bottom: the Millennium Simulation of the Universe. Image credit: Center for Brain Injury and Repair, University of Pennsylvania School of Medicine / Springel et al.
The human brain is a complex temporally and spatially multiscale structure in which cellular, molecular and neuronal phenomena coexist. It can be modeled as a hierarchical network, in which neurons cluster into circuits, columns, and different interconnected functional areas.
The structure of the neuronal network allows the linking between different areas, all devoted to process specific spatiotemporal activities over their neurons, forming the physical and biological basis of cognition.
The Universe, according to the large collection of telescope data gathered over many decades, seems to be reasonably well described by a physical model called the Lambda Cold Dark Matter model, which accounts for gravity from ordinary and dark matter, for the expanding space-time described by general relativity, and for the anti-gravitational energy associated to the empty space, called the dark energy.
Such model presently gives the best picture of how cosmic structures have emerged from the expanding background and have formed the cosmic web.
The most important building blocks of the cosmic web are self-gravitating dark matter dominated halos, in which ordinary matter has collapsed to form galaxies.
The initial distribution of matter density fluctuations was early amplified by the action of gravity, and has developed into larger groups or clusters of galaxies, filaments, matter sheets, and voids, in a large-scale web in all directions in space.
Although the relevant physical interactions in the above two systems are completely different, their observation through microscopic and telescopic techniques have captured a tantalizing similar morphology, to the point that it has often been noted that the cosmic web and the web of neurons look alike.
“We calculated the spectral density of both systems,” said co-author Dr. Franco Vazza, an astrophysicist at the University of Bologna.
“This is a technique often employed in cosmology for studying the spatial distribution of galaxies.”
“Our analysis showed that the distribution of the fluctuation within the cerebellum neuronal network on a scale from 1 micrometer to 0.1 mm follows the same progression of the distribution of matter in the cosmic web but, of course, on a larger scale that goes from 5 million to 500 million light-years.”
Dr. Vazza and his colleague, University of Verona neurosurgeon Alberto Feletti, also calculated some parameters characterizing both the neuronal network and the cosmic web: the average number of connections in each node and the tendency of clustering several connections in relevant central nodes within the network.
“Once again, structural parameters have identified unexpected agreement levels,” Dr. Feletti said.
“Probably, the connectivity within the two networks evolves following similar physical principles, despite the striking and obvious difference between the physical powers regulating galaxies and neurons.”
“These two complex networks show more similarities than those shared between the cosmic web and a galaxy or a neuronal network and the inside of a neuronal body.’
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F. Vazza & A. Feletti. The Quantitative Comparison Between the Neuronal Network and the Cosmic Web. Front. Phys, published online November 16, 2020; doi: 10.3389/fphy.2020.525731
