Brains, Worms and Computer Chips

"Brains are often compared to computers, but apart from the fact that both process information using a complex pattern of connections in a physical space, it has been unclear whether this is more than just a metaphor," said first author Danielle Bassett.

The scientists have uncovered principles that underlie the network organizations of the human brain, computer circuits, and the nervous system of the worm, known as nematode C. elegans. Using magnetic resonance imaging data from human brains, a map of the nematode's nervous system, and a standard computer chip, they examined how the elements in each system are networked together.

They found that all three shared two basic properties. First, the human brain, the nematode's nervous system, and the computer chip all have a Russian doll-like architecture, with the same patterns repeating over and over again at different scales. Second, all three showed what is known as Rent's scaling, a rule used to describe the relationship between the number of elements in a given area and the number of links between them.

Worm brains may seem to have very little in common with human brains and even less with computer circuits, explained Bassett. In fact, each of these systems contains a pattern of connections that are locked solidly in a physical space, similar to how the tracks in a railway system are locked solidly to the ground, forming traffic paths that have fixed GPS coordinates. A computer chip starts out as an abstract connectivity pattern, which can perform a specific function. Stage two involves mapping that connectivity pattern onto the two-dimensional surface of the chip. This mapping is a key step and must be done carefully in order to minimize the total length of wires –– a powerful predictor of the cost of manufacturing a chip –– while maintaining the abstract connectivity or function.

"Brains are similarly characterized by a precise connectivity which allows the organism to function, but are constrained by the metabolic costs associated with the development and maintenance of long 'wires,' or neurons," said Bassett. She explained that, given the similar constraints in brains and chips, it seems that both evolution and technological innovation have developed the same solutions to optimal mapping patterns.; Source: University of California - Santa Barbara