Book SummarySeven and a Half Lessons About the Brain, by Lisa Feldman Barrett

1-Page Summary1-Page Book Summary of Seven and a Half Lessons About the Brain

In Seven and a Half Lessons About the Brain, Lisa Feldman Barrett playfully addresses some common mysteries that surround the human brain. Published in 2020, her explanations shed light on the inner workings of the brain and how they impact feelings, behaviors, and relationships. Barrett argues that by understanding the basics of how your brain works, you can take a more active role in deciding how to think and behave. Her seven-and-a-half lessons explore how the brain evolved, how it’s organized, how it develops throughout our lifetimes, and how it works on its own and with other...

Seven and a Half Lessons About the Brain Summary Part 1: How the Brain Is Organized

Barrett begins with an explanation of how the brain is organized: not as a layered structure with specific parts and jobs, as has long been thought, but as a network of neurons (brain cells that receive and transmit information) that can all perform different tasks according to need. By understanding the brain’s organization, we can recognize the flexibility and resilience of the human brain and learn what makes it different from the brains of other animals.

Lesson: We Can’t Know How the Brain Works Based on Appearance Alone

Barrett argues that the way we traditionally think of the human brain is based on outdated research. There’s a popular belief that the human brain has three distinct parts, each with distinct functions: a brain core (or “lizard brain”), a limbic system, and a neocortex. The three-layer model of the brain has long been used as “proof” that the human brain is more evolved than other animal brains.

This model became popular in the mid-20th century when doctor Paul MacLean identified structural similarities and differences among the brains of different animals:

• Humans, mammals, and lizards have similar-looking brain cores. He called this...

Seven and a Half Lessons About the Brain Summary Part 2: How the Brain Operates

Turning from the brain’s organization to its functions, Barrett argues that the brain’s most important job isn’t thinking, it’s allostasis. Allostasis refers to the process of managing the body’s energy budget so it can survive and reproduce. All of its other functions (such as thinking) are secondary.

The Brain’s Most Important Function

While Barrett argues that the brain’s single most important job is managing the body’s energy budget, in The Body Keeps the Score, Bessel van der Kolk breaks down the brain’s primary role into several tasks, including:

• Signaling when your body needs essentials such as food, water, rest, shelter, safety, and sex

• Interpreting the world around you to point you in the right direction to find and satisfy those essential needs

• Creating the energy and initiating the actions to achieve those tasks

• Warning you of dangers and opportunities you may encounter as you pursue those tasks

• Adapting and responding to changing circumstances along the way

Half Lesson: How...

Seven and a Half Lessons About the Brain Summary Part 3: How the Brain Develops

So far we've explored the brain's hardware—its neurons, networks, and functions—but each individual's brain develops differently, based on a combination of their genes and their environment. According to Barrett, brain development depends on the interaction between the genetic information already present in the brain and the environment it develops in, and this interaction has great implications for the healthy development of children’s brains.

Lesson: The Brain Needs Lots of Help to Develop Successfully

Barrett explains that after birth, a baby’s brain develops according to its genetic coding and the physical and social environment. Genes help develop the basic infrastructure of the brain while environmental input triggers brain plasticity to develop certain neural connections more or less strongly.

Barrett identifies two specific processes that take place in the newborn’s brain as genes and the environment interact:

• Tuning: Important connections between neurons get stronger the more they’re used or the more essential they are for energy budgeting. For example, the baby learns to suck on a bottle or her mother’s breast very quickly because it’s a...

Seven and a Half Lessons About the Brain Summary Part 4: How Brains Collaborate

As we saw in Part 3, the brain requires input from our environment to properly develop. Long after it’s done developing, however, the brain continues to solicit information from other brains to perform daily tasks. This is what makes us social animals, and Barrett claims it has profound effects on our well-being.

Lesson: Brains Collaborate in Four Ways

Barrett explains that our brains are constantly collaborating with each other in four key ways:

1. Our interactions with other people encourage our neurons’ tuning process to strengthen certain neural connections over others. This process is particularly intense when we’re newborns, but it continues throughout life. For example, when you interact often with a person who speaks a different language, you might learn to speak some words in their language to communicate more easily with them.

(Shortform note: Anthropologists found another way that brains collaborate and impact each others’ well-being: They argue that our brain’s reliance on interaction is one reason for long human lifespans. Since young humans are...

Shortform Exercise: Reflect on How You Collaborate

The way our brains collaborate makes us a social species, which improves our day-to-day lives but also comes with responsibilities.

Barrett stresses the importance of empathizing with people who are different from us. Describe an experience when you spent time with someone with a different background, belief system, or culture. What was that like? For example, were you uncomfortable, or was it enjoyable?