Book SummaryA Thousand Brains, by Jeff Hawkins

1-Page Summary1-Page Book Summary of A Thousand Brains

Modern technological progress is ablaze with the potential for artificial intelligence to revolutionize everything we do, and yet we still don’t fully understand how natural, human intelligence works. Computer pioneers and neuroscientists believe that by understanding how the human brain functions, we can use that knowledge to create even more powerful and useful intelligent machines. Cracking the code of human and machine intelligence has become one of the most significant challenges of our time.

In A Thousand Brains, published in 2022, neuroscientist Jeff Hawkins explores the workings of human cognition and presents a new theory of intelligence rooted in the ability of each separate component of the brain to create models of the world and make predictions, just as the brain does as a whole. Through this novel framework for understanding intelligence, Hawkins points to new possibilities for advancements in AI and offers insights...

A Thousand Brains Summary How the Brain Works

To explain Hawkins’s ideas about how the human brain generates intelligence, we’ll have to explore how the brain works as a whole. We’ll cover how the brain’s newer structures (those that form what we call the neocortex) relate to its older, more primitive components. We’ll describe the fundamental building blocks of the neocortex, how they create mental models of the world, and how the same neural circuitry that lets us navigate our physical environment also gives us the capacity for abstract thought and contemplation.

Before Hawkins delves into his new theory of the brain, he takes a moment to review the older prevailing theory. The old model proposes that your brain processes sensory information, like vision and hearing, in a step-by-step manner like a flowchart. At the bottom of the chart, different nerves in your brain respond to simple features, such as lines and colors. As you move up the hierarchy, each new level of the brain responds to increasingly complex information from the regions below it.

Hawkins argues that while this theory explains some early neuroscience findings, it treats sensing as a static, one-way process, ignoring how your movements and changing...

A Thousand Brains Summary The Thousand Brains Theory

Before going into detail about how the brain’s various components operate, let’s consider the high-level perspective. In essence, Hawkins’s theory is that the brain is composed of thousands of nearly identical information processing units from which our awareness and intelligence emerge. We’ll begin by describing the functions of these units, how each supports a fraction of the brain’s total function, and how they coordinate with each other.

Hawkins proposes that the neocortex, the part of your brain responsible for higher cognitive functions, consists of around 150,000 cortical columns that each act as a mini-brain. We’ll describe these “cortical columns” in more detail later, but for the moment, suffice it to say that each column receives inputs, builds mental models, and makes predictions just as the brain does as a whole. The coordinated activity of these thousands of mini-brains working together produces the complex cognition and awareness that your brain is capable of.

(Shortform note: Hawkins attributes the discovery of cortical columns to Vernon Mountcastle in the 1950s, but as recently as 2005, [neuroscience research had failed to establish a definitive purpose for...

A Thousand Brains Summary The Old Brain and the New

Though the thousands of mini-brains that comprise your neocortex get all the credit for intelligent behavior, they’re far from the only important part of your brain. Instead, the neocortex is entirely dependent on the older, more primitive parts of your brain to interact with the outside environment at all. Here, we’ll expand on how the different parts of your brain interact, what functions the primitive parts of your brain perform, and how the two work together to build your understanding of the world.

Hawkins explains that the human brain is divided into two main parts—the Old Brain and the neocortex. From an evolutionary perspective, the Old Brain is ancient and is similar to that in many animal species. It’s responsible for maintaining your basic biological functions and reflexes. In contrast, the neocortex is a more recent evolutionary development. It’s much larger in humans than in other species, accounting for 70% of your brain and acting as the source of your intelligence. The neocortex processes sensory information and, in humans, is capable of complex cognitive functions such as language and...

A Thousand Brains Summary Cortical Columns

From the high-level view of the brain, let’s zoom in on the neocortex. In a way, the neocortex looks like a crumpled-up towel, but if you were to flatten it out, you’d see that it’s a single sheet made of layers of nerve cells. Looking even closer at the flattened neocortex, we’ll find that it’s chiefly composed of vertical “columns” of cells that form circuits capable of making predictions and creating models of anything the brain encounters.

According to Hawkins, cortical columns are the fundamental information processing units of the neocortex. Each cortical column—a “mini-brain” in its own right—consists of a vertical arrangement of brain cells (neurons) spanning the horizontal layers of the neocortex. The human brain has approximately 150,000 cortical columns, and despite serving a variety of functions—such as interpreting speech or remembering directions—every cortical column operates according to the same basic principles. This uniformity suggests that the brain processes every type of information using a standard set of rules, making the study of cortical columns crucial for understanding brain function as a whole.

(Shortform note: Research on cortical columns,...

A Thousand Brains Summary Models in the Mind

However many inputs they learn, no single neuron can create what we’d consider a coherent thought. That’s why Hawkins asserts that clusters of neurons with thousands of connections are needed to fully interpret your senses and generate your mind and body’s reactions. Working together, these clusters of neurons create models of your environment, decide what to do and think based on those models, and learn more information about the world when your current models prove insufficient.

Hawkins suggests that to make accurate predictions, cortical columns model objects and their positions in three-dimensional space using reference frames, which can be thought of like the grid lines on a map. His research shows that to create reference frames, neurons must be connected to both sensory input and motor output—it isn’t enough to see the world; your brain must be able to move through it. Different layers within a cortical column specialize in modeling objects and their positions separately—some neurons learn the shape of an object, while others determine where it exists. This modular setup lets the neocortex efficiently process and integrate information from your whole range of...

A Thousand Brains Summary From Neuroscience to AI

In addition to helping us better understand the human brain, the Thousand Brains Theory offers a promising avenue for advancing artificial intelligence research. To achieve Artificial General Intelligence (AGI)—a machine capable of learning and performing any intellectual task that a human can—Hawkins says that AI researchers should shift their approach to more closely mimic the structure and function of the neocortex. There are still many advantages the human brain has over AI, but researchers could design new AI structures to mimic the model-building aspects of the neocortex, while discarding any aspects of the Old Brain that aren’t needed to build an intelligent machine.

While AI has proven successful in specific domains, such as pattern recognition and language generation, Hawkins points out that current AI development techniques are fundamentally different from how the brain operates. One key difference between brains and AI is that brains learn continuously, constantly updating their mental models based on new experiences. Modern AIs, on the other hand, are trained on fixed datasets before being put in use and don’t learn or adapt during operation. Additionally, human...

A Thousand Brains Summary Into the Future

Addressing the dangers posed by both artificial and human intelligence will require ongoing research and dialogue. Assuming that we make an effort to address those issues, AI systems based on human cognition have the potential to greatly benefit humanity and its legacy. We can already predict the short-term uses of AI, but in the long run, the AIs we create might carry the human legacy into places we can’t yet conceive of.

By simulating the features of the neocortex, Hawkins says that Artificial General Intelligence (AGI) will be capable of learning and adapting to a wide range of tasks, making it more versatile and efficient than the specialized AI systems we have today. This flexibility will allow AGI to tackle complex, real-world problems, such as climate change or economic recessions, that require an understanding of multiple domains, from science and technology to psychology and social dynamics. Moreover, AGI could facilitate the rapid spread of knowledge, since learning acquired by one AI system should be easy to transfer to others, accelerating the pace of discovery and invention.

(Shortform note: The benefits of AGI that Hawkins describes don’t rely solely on AI....

Shortform Exercise: Reflect on How You Think

Hawkins presents a theory of the brain that suggests the thoughts you’re having right now are produced by thousands of mini-brains in your neocortex, each of which represents a small portion of your total cognitive abilities. Think about whether you find Hawkins’s theory plausible and what its implications might be.

What do you find surprising or counterintuitive about how Hawkins describes the brain’s higher functions? In what way does his explanation of the neocortex differ from your previous understanding of the brain?