EXERCISE: VICIOUS CYCLES I HAVE KNOWN
Happy habits are pathways that relieved your threatened feelings in the past. When you stop a happy habit, that sense of threat resurges and you feel like you are threatening your own survival. If you yield to this impulse, the old circuit builds. If you do nothing, you create space for a new circuit to grow. Learn to notice the impulse to relieve threatened feelings with happy habits. When you know that your threatened feeling is just a connection between neurons, you free yourself to build new connections. Notice examples of:
Someone you know with a habit that relieves threatened feelings
Someone’s habit having side effects
Your habit that relieves threatened feelings
Your habit having side effects
5 | HOW YOUR BRAIN WIRES ITSELF
Remaking Your Neural Connections
You were born with a lot of neurons but very few connections between them. Connections built as you interacted with the world around you, and they make you who you are. But you may want to remodel your circuits a bit. It seems like it should be easy because you built those circuits effortlessly in youth, but building new circuits in adulthood is surprisingly hard. Your old circuits are so efficient that avoiding them gives you the feeling that your survival is threatened. Any new circuits you build are flimsy by comparison. This is why change is difficult.
It helps to know how a brain actually builds its wiring, and that’s what we’ll discuss in this chapter. When you can appreciate how difficult it is to create new pathways, you can celebrate your persistence instead of berating your progress.
Five Ways Your Brain Builds Its Wiring
We mammals are born to create wiring instead of with wiring already established. Our circuits build as the world hits our senses and sends electricity to the brain. That electricity carves pathways that ease the flow of future electricity. Each brain is thus etched by its own experience. Following are five ways that experience physically changes your brain.
1. Experience Insulates Young Neurons
A neuron used repeatedly develops a fatty coating called myelin. This coating makes a neuron extremely efficient at conducting electricity, the way insulated wires are more efficient than bare wires. Myelinated circuits make a task feel effortless compared to doing it with slow, naked neurons. Myelinated neurons look white rather than gray, which is why we have “white matter” and “gray matter.”
Much of your myelination happens by age two, as your body learns to see and hear and move. When a mammal is born, it has to build a mental model of the world around it in order to survive. But you don’t need to relearn the experience that fire is hot and gravity makes you fall. That’s why myelin surges at birth and trails off by age seven.
Myelination increases again at puberty. That’s when a mammal needs to wire in new learning to improve its mating opportunity. Animals often move to a new group to mate, so they must learn to find food in new terrain and get along with new troop mates. Humans also seek mates in ways that involve learning the customs and survival strategies of a new tribe. The myelin surge of adolescence makes this possible. Natural selection built a brain good at rewiring its mental model of the world around puberty. We’ll discuss more about the importance of what’s learned in childhood and adolescence later in this chapter.
A MYELIN HIATUS
If you think myelin is “wasted” on the young, it helps to know there’s a good evolutionary reason. For most of human history, people had babies as soon as they reached puberty. They were busy meeting the immediate needs of the children who kept coming. Adulthood was spent investing in new brains rather than rewiring old brains.
Anything you do repeatedly in your “myelin years” develops huge, efficient branches in your neural network. This is why child prodigies exist, and why little kids on ski slopes whoosh past you even though you’re trying much harder than them. This is why new languages are hard to learn after puberty. You can learn new words, but you can’t seem to find the words when you need to express yourself. That’s because your new vocabulary is just skinny ungreased circuits. Your thoughts are generated by big myelinated circuits, so the electricity has trouble finding a place to flow.
Myelin also explains why it’s hard to unlearn a circuit you’d rather do without. Your white matter is so efficient that you feel inept when you try to do without it. That inept feeling motivates you to return to the old path, even when it’s not your best long-term survival choice. For example, if you’ve learned to feel strong by challenging other people, you may get yourself into trouble by challenging too much. But when you withhold your impulse to challenge, you might feel so weak that you blurt out a challenge. The opposite is true as well. You may have learned to feel safe by avoiding conflict, and you may get yourself into trouble by avoiding too much. But when you decide to challenge someone instead of avoiding conflict, you feel so unsafe that you quickly give up your new path and return to the old one.
The ups and downs of myelination can help you understand why certain current thought trends can be problematic:
When you hear that teen brains aren’t finished developing, remember that the brain does not mature automatically. It myelinates whatever it experiences. So if a teen gets rewards without doing the work, he “learns” that you can get rewards without effort. Some parents excuse a teen’s bad behavior by saying “his brain isn’t fully developed.” But that’s exactly why it’s so important to shape the experiences they are soaking up. Letting a teen escape responsibility for his actions forms a brain that expects to escape responsibility for its actions.
When you hear that an elderly brain can still learn, remember that the learning will not be easy, because myelination is so slow at this stage. Old brains build new learning only when a person engages in a lot of repetition. Service providers can help shape learning experiences, but they cannot build a circuit in someone else’s brain.
2. Experience Makes a Synapse Efficient
A synapse is the gap between one neuron and the next. The electricity in your brain only flows if it reaches the end of a neuron with enough force to jump across that gap. These barriers help us filter important inputs from irrelevant buzz.
What it takes for electricity to spark a synapse is surprisingly complex. It’s as if the tip of each neuron has a fleet of rowboats ready to ferry an electrical spark across the synapse to specially fitted docks on the next neuron. These rowboats get better at crossing over to their docks each time they’re set into motion, and that’s why experience improves the chances of a synapse firing. In a brain with 100 trillion synapses, experience helps channel your electricity in ways that promote survival.
You didn’t decide consciously which synapses to develop. It happens in two ways:
Repetition, which develops a synapse gradually
Emotion, which develops a synapse instantly
BUILDING SYNAPSES WITHOUT EMOTION
Synapses can build without neurochemicals, but it takes a lot of repetition. For example, you can learn romantic words in a foreign language quite quickly, but learning verb conjugations usually requires dreary repetition. Romance triggers neurochemicals that build synapses quickly, but repetition gives you the power to build any synapse you decide is important. If a synapse is activated many times, it gradually learns to transmit an electrochemical signal efficiently, even without extra rowboats in the fleet.
Emotions are chemical molecules that can change a synapse immediately and permanently. It’s as if you have more rowboats in the fleet harbored at that synapse. Whatever felt good or bad in your past developed synapses that will fire again more easily in the future. Here is a simple example: I used to carry popcorn on long plane trips and loved the tasty distraction. (Chewing is exercise!) But one day I chipped a tooth on my popcorn. Fear surged as I realized I was stranded in the air with no access to dentistry. The cortisol built strong new connections, and now I fear eating popcorn on a plane.
Your synapses built from
the repetition and emotion of your past. You are intelligent because your neurons connected in ways that reflect the good and bad experiences you’ve had. Some of those experiences were turbo-charged by molecules of pleasure or pain, and some were frequently repeated. When patterns in the world match the patterns in your synapses, electricity flows and you feel like you know what’s going on.
3. Only Neurons That Are Used Stick Around
Neurons that aren’t used begin to wither in the brain of a two-year-old. That enhances intelligence, surprisingly. Pruning helps a toddler focus on the circuits he’s built instead of spreading his attention everywhere the way a newborn does. A toddler can zoom in on things that felt good in his past, like a familiar face or the container that holds his favorite food. A toddler can also stay alert to things that felt bad in his past, such as a rough playmate or a closed door. The young brain is already relying on its own experience to steer toward meeting needs and away from potential threats.
The brain does much of its pruning between ages two and seven. This causes a child to link new experience to relevant past experience instead of storing each new experience as an isolated chunk. Richly interconnected networks are the source of our intelligence, and we create them by building new branches onto old trunks instead of building new trunks. So by the time you are seven, you are good at seeing what you have already seen and hearing what you have already heard.
You may think this is bad, so it’s important to see the value. Imagine lying to a six-year-old. She believes you, because her brain takes in everything. Now imagine telling that lie to an eight-year old. She questions it because her brain compares new inputs to stored experience instead of just absorbing all new inputs. New circuits are harder to build at age eight, which motivates a child to rely on her existing circuits. Your trust in your old circuits makes it possible for you to detect a lie. This had tremendous survival value in a world where parents died young and children had to meet their own needs at an early age.
You spent your early years developing some neural networks while allowing others to atrophy. Some of your neurons got swept away like autumn leaves, and that streamlined your thought process. You added new knowledge, of course, but you did that in areas where your electricity already flowed. If you were born into a hunting tribe, for example, you easily added more useful hunting information, and if you were born into a farming tribe, you had solid farming circuits to build onto. You ended up with a brain honed to survive in the world you actually lived in.
The zip of electricity through your circuits gives you the feeling that things make sense. When the world doesn’t fit your developed circuits, your electricity trickles so you have less confidence in your knowledge.
4. New Synapses Grow Between Neurons You Use
Each neuron can have many synapses because it can have many branches, or dendrites. New dendrites grow when there’s a lot of electrical stimulation. As dendrites grow toward hot spots of electrical activation, they may get close enough for electricity to jump the gap. Thus a new synapse is born. When this happens, you have a connection between two ideas.
You don’t feel your own synapses, but they’re easy to observe in others. A person who likes dogs seems to connect everything to dogs, and a person who likes technology often connects things to technology. A person who likes politics seems to connect everything to her political views, and a religious person easily connects things to his religious beliefs. One person sees positive connections and another person sees negative connections.
Whatever connections you have, you don’t experience them as tentacles grown by well-used neurons. You experience them as “the truth.”
5. Emotion Receptors Grow or Atrophy
For electricity to cross a synapse, the dendrite on one side must release a chemical that arrives at a receptor on the other side. Each of our brain chemicals has a complex shape that fits its own special receptors the way a key fits a lock. When you feel flooded by emotion, you are releasing more chemicals than those receptors can process. You feel overwhelmed and disoriented until your brain builds more receptors. That’s how you adapt when you are “going through something.”
FIVE WAYS EXPERIENCE CHANGES YOUR BRAIN
Experience insulates young neurons with myelin, so they’re superfast conductors of electricity.
Experienced synapses are better at sending electricity to neighboring neurons, so you’re better at lighting up a path you’ve lit up before.
Neurons atrophy if they’re not used, so you rely more heavily on the neurons you’ve used.
New synapses grow between neurons you use, so you make connections.
Receptors grow and atrophy, so it’s easier to process the feelings you experience repeatedly.
When a receptor is not used for a while, it disappears, which leaves space for any new receptors you may need. Flexibility is good, but it also means that you must use your happy receptors or lose them.
Happy chemicals float around seeking receptors they fit into. That’s how you “know” what you’re happy about. A neuron fires because a happy-chemical key has opened a receptor lock, and that firing develops the neurons that tell you where to expect happiness in the future.
Finding Your Free Will
You don’t always act on your neurochemical impulses because your prefrontal cortex can inhibit a response. It can even shift your attention from one activation pattern to another. We humans have the power to shift our attention from a circuit activated by the outside world to a circuit we activate internally. We are not powerless servants of our impulses because of this.
Your Limbic Brain and Cortex Work Together
When the information reaching your senses turns on your brain chemicals, it gets your attention. That’s the job these chemicals evolved to do. You are always deciding whether to “go with the flow” or divert your electricity elsewhere. You either act on your neurochemical impulse or generate an alternative. Then you decide whether to act on the alternative. You go for it if it stimulates happy chemicals. If not, you generate another alternative. This is how your separate brain parts work together. Your cortex comes up with options and your limbic brain responds to them as good for you or bad for you. You do this so efficiently that you hardly notice.
Animals do it too, but in a way that only requires a small cortex. An animal is always choosing between competing impulses to seek rewards and avoid pain. A human brain associates these impulses with related circuits in long chains of associations. You can anticipate the future before responding to an impulse. But eventually, you shift from thinking to acting, and neurochemicals help you do that. Electricity flows through your neural pathways, but you always have the power to redirect the flow. This is the core of your free will.
For example, if my husband does something that gets on my nerves, I could allow myself to dwell on it. Then my circuits would spark, my chemicals would gush, and I could tell myself he is causing the fireworks. But I am free in every moment to shift my attention elsewhere.
Focusing Your Attention on Survival
Your attention is limited. If you invest it in one place, you have less to invest in alternatives. It takes little attention to follow a familiar path, but shifting to the unfamiliar makes heavy demands on your attention. You have to juice up the weak signals to make sense of them, which leaves you less electricity for other efforts. You are always deciding which use of your electricity best promotes your survival.
Imagine your ancestor spotting a lion on the savannah. To survive, he focuses intensely on the lion to see which way it’s headed. At some point he decides to run, so he shifts his attention to the ground in front of him instead of the lion. You do this when changing lanes in traffic by shifting your attention between the rearview mirror and the cars themselves. Now imagine a person who spends most of his attention on web surfing. He is not conscious of deciding to invest his attention in that way. He often thinks of doing something else, but then a bad feeling comes up. A shift back to web surfing
relieves the bad feeling, creating the impression that it promotes his survival. His connections facilitate this flow, but he is always free to shift his attention elsewhere.
The brain often generates conflicting impulses. You want to eat pizza and you don’t want to. You want to write your opus and you don’t want to. You want to call your mother and you don’t want to. You are always deciding which impulse to act on and which to inhibit.
An ape is always doing that, too. When an ape sees a juicy mango, she wants it, but she also wants to avoid being bitten by the bigger ape next to her. She inhibits the impulse to grab while assessing all the survival-relevant information around her. You have more neurons than an ape, especially in the important prefrontal cortex. You can consider more options, and you can even generate options in your mind that you’ve never experienced in the sensory world. It all depends on where you direct your attention. When you don’t direct, your electricity flows down the path of least resistance.
How Small Experiences Create Big Circuits
Before there was “education,” and even before there was language, people learned survival skills from repetition and emotion.
Building Survival Circuits
A baby chimpanzee builds life skills while watching the world from his mother’s lap. Before he knows what food is, he sees crumbs fall from her mouth. They land on her chest right in front of his eyes. He has the urge to grasp a crumb and put it in his mouth because his mirror neurons have registered his mother doing that. It takes several tries because his muscles haven’t learned to grasp yet. He’s not driven by hunger because he’s fully nourished by her milk. When a crumb finally lands in his mouth, it feels good! His dopamine surges, and he makes a connection. The next time he sees a crumb, he expects more good feeling, so he goes for it. Without conscious intent, he builds the wiring that will enable him to meet his needs.
Habits of a Happy Brain Page 10