Brooks, David (2011-03-08). The Social Animal: The Hidden Sources of Love, Character, and Achievement (p. 47). Random House, Inc.. Kindle Edition.
Some scientists calculate that humans create 1.8 million synapses per second from their second month in utero to their second birthday. The brain makes synapses to store information. Each thing we know is embodied in a network of neural connections. … Harold could end up with something in the neighborhood of 100 trillion or 500 trillion or even 1,000 trillion synapses. If you want to get a sense of the number of potential connections between the cells in Harold’s brain, contemplate this: A mere 60 neurons are capable of making 1081 possible connections with each other. (That’s 1 with 81 zeroes after it.) The number of particles in the known universe is about one-tenth of this number. Jeff Hawkins suggests a different way to think about the brain. Imagine a football stadium filled with spaghetti. Now imagine it shrunk down to skull size and much more complicated. In their book The Scientist in the Crib, Gopnik, Meltzoff, and Kuhl have a nice description of the process neurons use to connect with one another: “It’s as if, when you used your cell phone to call your neighbor often enough, a cable spontaneously grew between your houses. At first, cells exuberantly attempt to connect to as many other cells as they can. Like phone solicitors, they call everyone, hoping someone will answer and say yes. When another cell does answer, and answers enough, a more permanent link gets laid down.”