Human brain

Welcome! I'm so excited to explore the incredible world of neuroscience with you. Before we dive into the anatomy of this amazing three-pound supercomputer, I'd love to know a little bit about what brings you here today. Are you studying the brain for a school class, or are you just curious to learn how your own mind works?

I'm just curious about how my mind works

It is wonderful to have you here! Exploring the brain out of pure curiosity is the best way to do it—after all, your brain is trying to understand itself.

Your path

Deep Dive: The Cerebrum and Cerebral Cortex

The Inner Brain and Supporting Systems

Brain Function and Maintenance

The Control Center

To understand how your mind works, we have to start with the physical hardware. At its core, the is a highly complex organ that serves as the primary control center for your entire nervous system.

It acts like a central processor, constantly receiving sensory information from the world, translating that data into thoughts and emotions, and sending out instructions to keep your body running. Before we look at how it creates thoughts, let's look at how it is built. The brain is structured into three main physical divisions, each with its own specific job.

A simplified 2D side-profile diagram of the human brain highlighting the cerebrum, cerebellum, and brainstem.

I have just started generating a visual map of these three areas for you. Let's take a look at what each of these parts actually does to keep you functional every day.

Continue to the three main structural divisions

Let's explore those three main divisions shown in the diagram. Each one handles a completely different level of your daily experience, from your highest creative thoughts down to your basic survival.

The Cerebrum, Cerebellum, and Brainstem

First up is the cerebrum, which is the massive, wrinkled outer layer making up about 85% of your brain's weight. This is where your conscious mind lives. When you plan your day, feel happy, imagine a new idea, or recall a childhood memory, you are using your cerebrum. Tucked neatly under the back of the cerebrum is the cerebellum, a Latin name meaning "little brain." While it looks like a mini wrinkled baseball, it is your body's master coordinator. It doesn't initiate movement, but it acts like an orchestra conductor—taking raw signals for movement and smoothing them out so you can walk, run, or play an instrument without losing your balance. Finally, sitting at the base of the brain is the . This is the most ancient part of your hardware, connecting your brain directly to your spinal cord. The brainstem is your autopilot, keeping you alive by constantly managing involuntary functions that you never have to think about.

Continue to the difference between gray and white matter

The Colors of the Mind

Now that we have looked at the physical landscape, let's zoom in slightly to look at the actual tissue that makes up these regions. If you were to look at a cross-section of a fresh brain, you would immediately notice two distinct shades: and .

An easy way to think about this is to picture a massive, busy corporate headquarters. Gray matter represents the individual offices where the workers actually sit, think, and make decisions. White matter represents the high-speed fiber-optic cables and hallways connecting all those offices together, allowing everyone to share information instantly. In the cerebrum, the gray matter sits on the outside like a protective crust, while the white matter fills the inside to route signals back and forth. Interestingly, in your spinal cord, this pattern is completely reversed!

A cross-section of a human brain showing the outer gray matter cortex and the branched inner white matter tracts.

I have started generating a diagram showing how these two layers are arranged inside your cerebrum.

Before we move on to the next subtopic, how are you feeling about these introductory concepts? Would you like to do a quick self-test to make sure you have got the basics down?