The Human Brain

Katie is taking a class in neuroscience, but she's really confused. She's always heard that different parts of the brain are responsible for different functions, but in her class, she's heard that there are actually three brains, not one. What's going on?

Neuroscience is 'the study of the brain.' There are many different ways to study the brain, and many different ways to divide the brain up into different regions. One way to divide up the brain is by thinking of it as three different brains, the hindbrain, midbrain, and forebrain. Of course, they aren't actually three different brains, but they do control different things. Let's look closer at the three sections of the human brain and their functions.

Hindbrain

With names like hindbrain, midbrain and forebrain, Katie is already wondering if she might know where the different segments of brain are. And she's probably right.

The hindbrain, which consists of the medulla, cerebellum, and pons, is the section of the brain that is in the rear and bottom of the human brain. In other words, it's in the hind part of the human brain. It connects the brain to the spinal cord, and by extension, the rest of the body.

Some people think about the hindbrain as being responsible for the basic functions in life. This part of Katie's brain isn't doing any algebra! But it does make sure that she breathes, sleeps, and keeps her balance as she walks, among other things. In other words, it makes sure that Katie can live and function. She doesn't have to think about the functions that the hindbrain serves; the functions just get done because the hindbrain is there, in the back of her head, doing its thing.

Midbrain

If the hindbrain is in the hind part of the head, Katie is pretty sure that the midbrain is, well, in the middle. And she's right. The midbrain includes the tectum, superior and inferior colliculi, tegmentum, and the substantia nigra.

Together, the midbrain and hindbrain are called the brainstem, and as part of the brainstem, the midbrain works closely with the hindbrain and can help support it, as well as carrying some types of information from the hindbrain to other parts of the brain.

The most important thing to know about the midbrain, though, is that it is the seat of dopamine pathways in the brain. Dopamine is a neurotransmitter that is responsible for many things, including regulating mood, causing that rush you feel when you take drugs or eat chocolate, helping with memory, and coordinating muscle movements. Most dopamine pathways start in the midbrain, which means that without it, none of these things can happen. So the next time Katie feels really happy after eating chocolate, she should thank her midbrain!

Forebrain

Okay, Katie gets that the brainstem is in charge of basic functions. The hindbrain makes sure that she's breathing and sleeping, among other things, and the midbrain, the other part of the brainstem, helps regulate her mood and makes her feel that rush she gets when she does something fun or eats something delicious.

But what area of the brain is in charge of things like higher-level thinking skills or personality? In other words, what part of the brain is responsible for thinking and behaving?

The forebrain is at the very top, or forward, part of the brain. It includes the cerebral cortex and subcortical regions. The cerebral cortex is what most people think of when they think of the brain: it's the surface of the brain that has lots of wrinkles in it. The cerebral cortex is divided into four lobes, the parietal, temporal, occipital, and frontal lobes. They are each responsible for different things, including higher-level thinking, personality, vision, language, voluntary movement, and memory.

Subcortical regions are part of the forebrain that is below the cerebral cortex. It includes, among many other structures, the thalamus, which is kind of like the Grand Central Station of the brain, because almost all information coming into the brain from the body goes through the thalamus. Another major subcortical structure is the amygdala, which is an almond-shaped structure next to the thalamus that is in charge of many basic emotions, like fear and anger. Katie doesn't have trouble remembering the amygdala, because every time she gets anxiety, she likes to eat almonds to calm down. Almonds and fear...that's the amygdala! When Katie thinks about her five senses, thinking, and personality, she's thinking of the types of things that the forebrain is in charge of.

Lesson Summary

The human brain can be divided into three general regions. The hindbrain consists of the medulla, pons, and cerebellum and is in charge of basic functioning, like breathing, sleeping, and coordination. The midbrain includes the tectum, tegmentum, superior and inferior colliculi, and substantia nigra, and it is the seat of dopamine pathways in the brain. Together, the hindbrain and midbrain are called the brainstem.

Finally, the forebrain includes the cerebral cortex and subcortical regions. The cerebral cortex consists of the parietal, temporal, occipital, and frontal lobes, which control the five senses, voluntary movement, higher-level thinking, and personality. Subcortical regions, which are below the cerebral cortex, include the thalamus, through which almost all information from the body travels, and the amygdala, which is in charge of basic emotions like fear and anger.

The Human Brain Overview

Neuroscience

the study of the brain

Hindbrain

consists of the medulla, cerebellum, and pons

Midbrain

includes the tectum, superior and inferior colliculi, tegmentum, and the substantia nigra

Brainstem

the midbrain and hindbrain

Dopamine pathways

a neurotransmitter that is responsible for many things, including regulating mood, helping with memory, and coordinating muscle movements

Forebrain

at the very top, or forward, part of the brain

Cerebral cortex

divided into four lobes, the parietal, temporal, occipital, and frontal lobes

Subcortical regions

part of the forebrain that is below the cerebral cortex

Thalamus

almost all information coming into the brain from the body goes through here

Amygdala

an almond-shaped structure next to the thalamus that is in charge of many basic emotions, like fear and anger