Come around to Barney Kiernan’s, says Joe. I want to see the citizen.
At their most fundamental level, brains are made up of neurons. And those neurons collectively comprise the two main types of brain tissue: white matter is made up primarily of axons, and grey matter is made up of synapses, or the connections between neurons.
Grey matter exists as a thin, relatively flat sheet covering the rest of the brain, and is referred to as the cortex. When you compare the brains of different mammal species, you find that certain measurements of brain structure scale in similar ways. In other words, variables like grey matter volume, total number of synapses, white matter volume, number of neurons, surface area, axon diameter, and number of distinct cortical “areas” maintain common mathematical relationships with each other, whether you’re looking at the brains of mice, rabbits, dogs, cats, hyenas, kangaroos, bats, sloths, bonobos, or humans. (…)
Lots of networks have been compared to urban systems. (…) To what extent, though, might a brain be like a city? There’s the obvious analogy: neurons are like highways. Neurons are channels that carry information in the form of electric signals from one location within the brain to another, while highways are channels that transport people and materials from one location within a city to another. Cognitive scientists Mark Changizi and Marc Destefano think that the analogy goes deeper. (…) They argue that the organization of city highway networks is driven over time by political and economic forces, rather than explicitly planned based on principles of highway engineering – which means that city highway systems may be subject to a form of selection pressure similar to the selection pressure exerted on biological systems.
photo { Keith Davis }
