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About the brain

The brain is made up of billions of nerve cells that communicate through electrical and chemical activity. Weighing around 1.5 kg the brain is cushioned within the skull by cerebrospinal fluid which circulates around the brain through a series of cavities called ventricles.

The brain makes up only two percent of the body’s weight but uses 20% of the oxygen supply and blood flow. Brain cells are quite fragile and need protection from trauma, pressure, infection, poisoning or lack of oxygen. They begin to die if they do not receive oxygen after three to five minutes.

The brain is divided into many parts, which have specific functions and work together.

Hemispheres of the brain

For much of the 20th Century, it was believed that the two hemispheres of the brain were highly specialised and responsible for everything from which hand you prefer to write with top your personality. You have probably heard people talking about how the left-brain is all about language and logic, and the right brain is creative and visual. Although there is a small amount of truth to this, the reality is far more complicated. The two hemispheres work seamlessly together perceiving, processes, and integrating information.


In many people (but certainly not all people) the right hemisphere is more involved in the following activities: controlling parts of the left half of the body; perceiving processing visuospatial information; recognising the emotional aspects of speech and some other emotional cues from others; some kinds of emotional regulation; finding your way through familiar surroundings; some aspects of self- awareness; and some aspects of metaphor and humour.


Likewise, in many people (but not all) the left hemisphere is more involved in: Controlling the right side of the body; speech production; understanding words; understanding sign language; following sequential directions; and focusing the attention.

Communication and collaboration between the two hemispheres is vital for all brain functions.

For example, although the left hemisphere processes information relating to the meaning of language, the right hemisphere adds important information about the emotional aspects of speech.

Lobes of the brain

Each hemisphere of the brain is divided into four lobes.


The frontal lobes are involved in problem-solving, planning, making judgments, abstract thinking. They also regulate how we act upon our emotions and impulses. Changes in a person’s personality and social skills can occur from damage to this area.


The temporal lobes play a role in auditory information processing, particularly the ability to hear and understand language. They are also concerned with memory, the emotions, the ability to enjoy music and to recognise and identify things we see, such as faces or objects.


The parietal lobes are concerned with the perception of sensations, such as touch, pressure, temperature and pain. They deal with spatial awareness, such as our ability to find our way around a house, to drive a car and to reach for objects. They are also involved with the understanding of words and sentences, reading and writing and sometimes the ability to use numbers.


The occipital lobes are mainly connected with vision but also with our ability to recognise what we see. Our ability to see objects accurately, identify colours and locate objects in the environment comes from the occipital lobes.

Other parts of the brain

The cerebellum

The cerebellum is involved in “doing” rather than “thinking” activities. It is located at the back and below the main hemispheres of the brain. It controls balance and the muscle coordination needed for large body movements. It lets a person know how fast, how hard, how far and in what direction his or her body parts are moving.

The brain stem

The brain stem connects the brain to the spinal cord and regulates basic activities. These include breathing, blood pressure, blood circulation, swallowing, appetite, body temperature and digestion, as well as the need for water, staying awake and sleeping.

The effects of brain injury

Each part of the brain deals with different aspects of what we think, feel and do, so injury to specific areas can cause many different problems to occur. The good news is that the brain does have some ability to heal itself. There are many rehabilitation strategies to compensate for the effects of brain injury.

Further information

For a dynamic view of the brain take a look at InformED’s Brain Map