When a male vole repeatedly mates with a female, a hormone called vasopressin is released in his brain. The vasopressin binds to receptors in a part of the brain called the nucleus accumbens, and the binding mediates a pleasurable feeling that becomes associated with that female. This locks in the monogamy, which is known as pair-bonding. If you block this hormone, the pair-bonding goes away.

What we find is that our brains have colossal things happening in them all the time.

The three-pound organ in your skull - with its pink consistency of Jell-o - is an alien kind of computational material. It is composed of miniaturized, self-configuring parts, and it vastly outstrips anything we've dreamt of building.

In the traditionally taught view of perception, data from the sensorium pours into the brain, works its way up the sensory hierarchy, and makes itself seen, heard, smelled, tasted, felt - "perceived." But a closer examination of the data suggests this is incorrect. The brain is properly thought of as a mostly closed system that runs on its own internally generated activity.

We are not at the center of ourselves, but instead - like the Earth in the Milky Way, and the Milky Way in the universe - far out on a distant edge, hearing little of what is transpiring.

It turns out your conscious mind - the part you think of as you - is really the smallest part of what’s happening in your brain, and usually the last one in line to find out any information.

As Walt Whitman correctly surmised, we are large and we harbor multitudes within us. And those multitudes are locked in chronic battle. There is an ongoing conversation among the different factions in your brain, each competing to control the single output channel of your behavior. As a result, you can accomplish the strange feats of arguing with yourself, cursing at yourself, and cajoling yourself to do something - feats that modern computers simply do not do.