The Brain: The Story of You

by David Eagleman

Given the brain’s centrality to our lives, I used to wonder why our society so rarely talks about it, preferring instead to fill our airwaves with celebrity gossip and reality shows. But I now think this lack of attention to the brain can be taken not as a shortcoming, but as a clue: we’re so trapped inside our reality that it is inordinately difficult to realize we’re trapped inside anything. At first blush, it seems that perhaps there’s nothing to talk about. Of course colors exist in the outside world. Of course my memory is like a video camera. Of course I know the real reasons for my beliefs.

In a sense, the process of becoming who you are is defined by carving back the possibilities that were already present. You become who you are not because of what grows in your brain, but because of what is removed.

Although most of the changes are too small to detect with the naked eye, everything you’ve experienced has altered the physical structure of your brain – from the expression of genes to the positions of molecules to the architecture of neurons. Your family of origin, your culture, your friends, your work, every movie you’ve watched, every conversation you’ve had – these have all left their footprints in your nervous system. These indelible, microscopic impressions accumulate to make you who you are, and to constrain who you can become.

I am a sentient being. I experience my existence. I feel like I’m here, looking out on the world through these eyes, perceiving this Technicolor show from my own center stage. Let’s call this feeling consciousness or awareness.

Consciousness emerges when neurons are coordinating with one another in complex, subtle, mostly independent rhythms. In slow-wave sleep, neurons are more synchronized with one another, and consciousness is absent.

Twenty percent of the calories we consume are used to power the brain. So brains try to operate in the most energy-efficient way possible, and that means processing only the minimum amount of information from our senses that we need to navigate the world.

The real world is not full of rich sensory events; instead, our brains light up the world with their own sensuality.

In terms of the brain, consciousness is a way for billions of cells to see themselves as a unified whole, a way for a complex system to hold up a mirror to itself.

our lives are steered by forces far beyond our capacity for awareness or control.

pop!pop!pop! – it’s impossible not to be awed. After all, this is what every decision in the history of our species sounded like. Every marriage proposal, every declaration of war, every leap of the imagination, every mission launched into the unknown, every act of kindness, every lie, every euphoric breakthrough, every decisive moment. It all happened right here, in the darkness of the skull, emerging from patterns of activity in networks of biological cells.

And unlike animals, we can often put these rewards ahead of biological needs. As Read Montague points out, “sharks don’t go on hunger strikes”: the rest of the animal kingdom only chases its basic needs, while only humans regularly override those needs in deference to abstract ideals. So when we’re faced with an array of possibilities, we integrate internal and external data to try to maximize reward, however it’s defined to us as individuals.

Mentally, we can disconnect from the present moment and voyage to a world that doesn’t yet exist.

Instead, the key business of brains is to predict. And to do this reasonably well, we need to continually learn about the world from our every experience.

neural networks that desire instant gratification – that is, those networks that want things now. Because the seduction of the immediate satisfaction pulls so strongly on our decision making, the housing bubble can be understood not simply as an economic phenomenon, but also as a neural one.

This sort of deal between your present and future self is known as a Ulysses contract.

And that’s why resisting temptation, making hard decisions, or taking initiative all seem to draw from the same well of energy. So willpower isn’t something that we just exercise – it’s something we deplete.

Some people argue that drug addiction is about poverty and peer pressure. Those do play a role, but at the core of the issue is the biology of the brain. In laboratory experiments, rats will self-administer drugs, continually hitting the delivery lever at the expense of food and drink. The rats aren’t doing that because of finances or social coercion. They’re doing it because the drugs tap into fundamental reward circuitry in their brains. The drugs effectively tell the brain that this decision is better than all the other things it could be doing.

Without the ability to weigh alternatives, we would be hostages to our most basic drives. We wouldn’t be able to wisely navigate the now, or plan our future lives. Although you have a single identity, you’re not of a single mind: instead, you are a collection of many competing drives. By understanding how choices battle it out in the brain, we can learn to make better decisions for ourselves, and for our society.

Although we typically feel independent, each of our brains operates in a rich web of interaction with one another – so much so that we can plausibly look at the accomplishments of our species as the deeds of a single, shifting mega-organism.

to the brain social rejection is so meaningful that it hurts, literally.

The medial prefrontal cortex is involved in thinking about other people – at least, most other people. As he puts it, by shutting down the systems that see the homeless person as a fellow human, one doesn’t have to experience the unpleasant pressures of feeling bad about not giving money. In other words, the homeless have become dehumanized: the brain is viewing them more like objects and less like people. Not surprisingly, one is less likely to treat them with consideration. As Harris explains: “if you don’t properly diagnose people as human beings, then the moral rules that are reserved for human people may not apply.”

We’ve seen that our brains can be manipulated by political agendas to dehumanize other people, which can then lead to the darkest side of human acts.

Your neurons and those of everyone on the planet interplay in a giant, shifting super-organism.

There are at least a hundred billion other galaxies in our cosmos, each of which contains a hundred billion stars. We’ve already spotted thousands of exoplanets orbiting those stars, some of which have conditions quite like our Earth.