Book summary: 7 and a half lessons about the brain

Your Brain is not for Thinking

When it came to body budgeting, predication beat reaction. A creature that prepared its movement before the predator struck was more likely to be around tomorrow than a creature that awaited a predator’s pounce. Creatures that predicted correctly most of the time, or made non-fatal mistakes and learned from them, did well. Those that frequently predicted poorly, missed threats, or false-alarmed about threats that never materialized didn’t do so well. They explored their environment less, foraged less, and were less likely to reproduce.

The scientific name for body budgeting is allostasis. It means automatically predicting and preparing to meet the body’s needs before they arise.

Your brain’s most important job is to control your body - to manage allostasis - by predicting energy needs before they arise so you can efficiently make worthwhile movements and survive. Your brain continually invests your energy in the hopes of earning a good return, such as food, shelter, affection, or physical protection, so you can perform nature’s most vital task: passing your genes to the next generation.

We do not experience feelings or things we do as a deposit or withdrawal in our metabolic budgets, but under the hood, that is what’s happening.

Lesson 1: We Only Have One Brain

The triune brain idea is one of the most successful and widespread errors in all of science.

It turns out that brains become larger over evolutionary time, they reorganize.

Because the manufacturing process runs in stages, and the stages last for shorter or longer durations in different species. The biological building blocks are the same; what differs is the timing.

Your brain is not more evolved than a rat or lizard brain, just differently evolved.

What we call metal illnesses, then, may be rational body-budgeting for the short term that’s out of sync with the immediate environment, the needs of other people, or your own best interests down the road.

Lesson 2: Your Brain is a Network

Your brain is a network - a collection of parts that are connected to function as a single unit.

Neurons are grouped into clusters that are like airports. Most of the connections in and out of a cluster are local, so, like an airport, the cluster serves mostly local traffic. In addition, some clusters serve as hubs for communication.

Hubs are points of vulnerability because they are points of efficiency - they make it possible to run a human brain in a human body without depleting a body budget.

Your brain network is not static - it changes continuously.

Some changes are extremely fast. Your brain wiring is bathed in chemicals that complete the local connections between neurons. These chemicals are called neurotransmitters (such as dopamine), and they make it easier or harder for signals to pass across synapses.

Overall, no neuron has a single psychological function, though a neuron may be more likely to some functions than others.

Degeneracy in brain means that your actions and experiences can be created in multiple ways. Each time you feel afraid, for example, your brain may construct that feeling with various sets of neurons.

Brains of higher complexity can remember more. A brain doesn’t store memories like computer - it reconstructs them on demand. We can this process remembering but it’s really assembling.

Lesson 3: Little Brains Wire Themselves to Their World

A little brain wires itself to its environment, and when that environment is missing key elements for healthy body budgeting, critical brain wiring can be pruned away.

E.g. Kids that nobody shared attention with tend to have difficulty concentrating and resisting distractions.

Why evolution got our species into this precarious situation in the first place? We can’t know for sure but one guess is: This arrangement helps our cultural and social knowledge flow efficiently from generation to generation.

Lesson 4: Your Brain Predicts Everything You Do

Your brain combines information from outside and inside your head to produce everything you see, hear, smell, taste, and feel.

In the famous “dog-bell” experiment, the dogs were not reacting to the sound by drooling. Their brains were predicting the experience of eating food and preparing their bodies in advance to consume it.

In a very real sense, predictions are just your brain having a conversation with itself. A bunch of neurons make their best guess about what will happen in the immediate future based on whatever combination of past and present your is currently conjuring. Those neurons then announce that guess to neurons in other brain areas, changing their firing. Meanwhile, sense data from the world and your body injects itself into the conversation, confirming (or not) the prediction that you’ll experience as your reality.

If your brain has predicted well, then your neurons are already firing in a pattern that matches the incoming sense data. That means this sense data itself has no further use beyond confirming your brain’s predictions. What you see, hear, smell, and taste in the world and feel in your body in that moment are completely constructed in your head.

Brains aren’t wired for accuracy. They’re wired to keep us alive.

All this predicting happens backward from the way we experience it. You and I seem to sense first and act second. You see an enemy and then raise your rifle. But in your brain, sensing actually comes second. Your brain is wired to prepare for action first.

Your brain predicts and prepares your actions using your past experience. If you could magically reach back in time and change your past, your brain would predict differently today, and you might act differently and experience the world differently as a result.

It’s impossible to change your past, but right now, with some effort, you can change how your brain will predict in the future. You can invest a little time and energy to learn new ideas. You can curate new experiences. You can try new activities. Everything you learn today seeds your brain to predict differently tomorrow.

Things that require effort today become automatic tomorrow with enough practice. They’re automatic because your brain has tuned and pruned itself to make different predictions that launch different actions. As a consequence, you experience yourself and the world around you differently. That is a form of free will, or at least something we can arguably call free will. We can choose what we expose ourselves to.

Sometimes we’re responsible for things not because they’re our fault, but because we’re the only ones who change change them.

Lesson 5: Your Brain Secretly Works with Other Brains

Your brain changes its own wiring after new experiences, a process called plasticity.

This remodeling job requires energy from your body budget, so your predicting brain needs a good reason to splurge. And a great reason is that the connections are used frequently to deal with the people around you. Little by little, your brain becomes tuned and pruned as you interact with others.

But there’s a catch - when people are less familiar with you, it can be harder to empathize. You might have to learn more about that person, an extra effort that translates into more withdrawals from your body budget, which can feel unpleasant. This may be one reason why people sometimes fail to empathize with those who look different or believe different things that they do and why it can feel uncomfortable to try.

Simply put, a long period of chronic stress can harm a human brain.

Anything that contributes to chronic stress can gradually eat away at your brain and cause illness in your body. This includes physical abuse, verbal aggression, social rejections, sever neglect, and the countless other creative ways that we social animals torment one another.

Lesson 6: Brains Make more than One Kind of Mind

It’s important for humans to have many kinds of minds, because variation is critical for the survival of a species. Even though variation is the norm - and a blessing for our species - it makes people uneasy. The idea of a single, universal human nature is so much more comfortable than continuous variation.

One of the closest things we have to a universal mental feature, is mood - the general sense of feelings that comes from your body. Scientists call it affect. Feelings of affect range from pleasant to unpleasant, from idle to activated. Affect is not emotion; your brain produces affect all the time, whether you’re emotional or not and whether you notice it or not.

Your brain summarize what’s going on with your body in the moment, and you feel that summary as affect.

Lesson 7: Our Brains Can Create Reality

Social reality means that we impose new functions on physical reality. Social reality is a uniquely human ability. Scientists don’t know for sure how our brains developed this capacity, but we suspect it has something to do with a suite of abilities that I‘lol call the Five Cs: creativity, communication, copying, cooperation, and compression.

Your brain can make a big, fat, compressed summary of summaries of summaries. Compression makes it possible for your brain to think abstractly, and abstraction, together with the rest of the Five Cs, empowers your large, complex brain to create social reality.