How does the brain work?

Did you know that it is the left side of the brain that controls the right side of your body and vice versa?

Featured image

Most people know that the brain is divided in two halves called hemispheres by the cerebral fissure… But did you know that it is the left side of the brain that controls the right side of your body and vice versa? The brain is a very complicated organ, which we are going to discover and explain to you now.

Firstly, you need to know that what you see when you think of a brain is only the very surface. What you do imagine is usually the cerebral cortex, a wrinkly and pink, flesh like tissue, the exterior part of the brain. This part is the one that processes the sensory information brought by the sensory neurons (See “How does the nervous system function”). As you may know, we have different senses, and that is why we have different lobes. Each lobe of the cerebral cortex is responsible for a different function.

The lobes of the brain

Brain lobes

The frontal lobe, here represented in red, is considered to be the most important as it is responsible for a lot of important features such as motor functions, the ability to think and to talk. It is the largest lobe of the brain because of the range of important tasks it takes care of.

The temporal lobe, here represented in light blue, has two main functions. The most important function is the creation of memories as it is in this lobe that is situated the hippocampus which we’ll learn about later on. The second function is being the home of the primary auditory cortex which, as its name says, is used to interpret the sounds our ears perceive.

The parietal lobe, here represented in yellow, is the lobe responsible for our ability to feel, and to process and interpret the body’s senses, such as the touch or taste.

The occipital lobe, here represented in green, is the one that contains our primary visual cortex which is used to interpret the images we see.

The components of the brain

Parts of the brain

As mentioned earlier, the brain isn’t simply composed of the cerebral cortex; the pinkish and flesh tissue is only the surface. The brain is composed of many more separate organs which all have their functions, but we will simply bring up the essentials as some have very complicated and in depth functionalities.

One of the essential parts of the brain is the cerebellum, not to be confused with the cerebrum. Nicknamed the “Little brain”, the cerebellum occupies the lowest spot on the brain and it is the part with the highest concentration of neurons in the body. It uses the auditory and visual systems for balance, and helps with the coordination of movements. This is why we say that our hearing is very important to stand up; without it, the brain loses balance and the body topples over.

Then come the thalamus and the hypothalamus. The thalamus, located at the center of the brain, sorts out information and serves as a relay station for messages coming from both ends: it relays the information the brain sends, but also the one from the nervous system and the senses to the parts of the brain they’re destined to. The hypothalamus, located just under the thalamus as indicates its name, has a lot of control and importance in the body. This is the part that controls things such as body temperature and the circadian rhythms (daily cycles in physiological state and behaviour) and monitors vital notions such as thirst and hunger, but also sexual desire and emotions.

The brain stem’s main aim is to be the link between the brain and the spinal cord, but has other functions as well. Itself composed of different parts called the pons and the medulla, it is responsible for other vital functions such as controlling the heart rate, the blood pressure, or even breathing. It also is very important when asleep as it controlls the cycles between the awake and asleep states of the body, as well as the cycles in sleep itself such as REM sleep for example.

Finally, the hippocampus is in charge of the creation of memories, as well as their storage. The association between smell or taste and memory comes from the hippocampus, and that’s why it is believed to also have ties with emotions and how they can be handled. It also has a role in our special ability to learn, to assimilate techniques and replicate them later on. The degradation of the hippocampus can result in Alzheimer’s disease for example.


The brain is a beautifully complicated thing, and it is full of mysteries. So many questions about the brain remain, with answers we may never find or understand. It truly is one of the wonders of this world.

Written by Baptiste, translated by Rémy