Neuronal and galaxy networks are remarkably similar, according to an astrophysicist and neuroscientist team. Both structures are also more alike to each other than either one is to the interior of a neuronal body or the interior of a galaxy, respectively.
The observable universe contains 100 billion galaxies, while the human brain contains about the same number of neurons and non-neuronal cells.
Visually, a computer simulation of the cosmic web and a cross-section of brain tissue have a similar structure of filaments embedded with bodies (cells or galaxies). The cosmic web consists of all the stars, gas and dark matter in the universe.
The cosmic web and human brain have a similar complexity. This is estimated by measuring the size of the smallest computer program that could predict the behavior of a network. For cosmic networks, this is 1 to 10 petabytes of data. The memory capacity of the human brain is around 2.5 petabytes. In other words, “the entire life experience of a person can also be encoded into the distribution of galaxies in our universe.”
In comparing these two structures, the researchers faced a number of challenges, such as differing sources of data: telescopes and simulations for galaxy networks; versus electron microscopy, immunohistochemistry, and functional magnetic resonance for neuronal networks.
Vastly different scales: a neuronal network fits inside your head, but the cosmic web a structure made up of all of the universe’s galaxies stretches across tens of billions of light-years.
While computer simulations of the evolution of the cosmic web have been carried out, none have been performed for the human brain. In lieu of that, the researchers estimated the complexity of the brain based on its intelligence and cognition.
The researchers also found that the power spectra of the cosmic web and the human brain are not fractal. Fractal patterns show up in other complex systems, such as tree branches, clouds and water turbulence. The non-fractal nature of the cosmic web and brain suggests that they may be “scale-dependent, self-organized structures.”
Scientists also calculated other parameters that characterize both the neuronal network and the cosmic web: the average number of connections in each node and the tendency of clustering several links in relevant central nodes within the system.
Programs like the Human Brain Project, designed to simulate an entire human neuronal network, and the Square Kilometer Array, the biggest enterprise ever in radio astronomy, will help us fill in some of these details and understand whether the universe is even more surprising than we thought.
The eye immediately grasps some similarity between images of the cosmic web and the brain. In Figure 1 we show a simulated distribution of cosmic matter in a slice 1 billion light-years across, along with a real image of a 4 micrometers thick slice through the human cerebellum.
Within both systems, only 30% of their masses are composed of galaxies and neurons. Within both systems, galaxies and neurons arrange themselves in long filaments or nodes between the filaments.
Finally, within both systems, 70% of mass or energy distribution comprises components playing a passive role: water in the brain and dark energy in the observable Universe.
"Once again, structural parameters have identified unexpected agreement levels. 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".
The encouraging results of this pilot study are prompting the researchers to think that new and effective analysis techniques in both fields, cosmology, and neurosurgery, will allow for a better understanding of the routed dynamics underlying the temporal evolution of these two systems.