A beginner's guide to the brain
This section offers an introduction to the way the brain operates, and how it might be affected by an injury.The brain is the most complex, mysterious part of our body.1 Weighing about 3lbs, this relatively small organ is nothing less than the engine room of our behaviour and the way we see the world. It makes up just two per cent of our weight, but looks after a massive 98 per cent of our functions.2 This miniature supercomputer not only gathers and processes information from all of our senses, it also sends out lots of information, telling our limbs to move and our eyes to blink. Importantly, it also determines the way we behave, the things we say, and our complex thought processes.
Brain injury comes in many different forms.
But there may be a relationship between someone’s behaviour after their injury and the part of the brain that’s been injured.
The brain is like other parts of our body in some ways.
It bruises and swells when injured just as a thumb or a toe might.
But in some crucial ways it is very different.
The 100 billion nerve cells in our brain are all connected with other cells many times over, forming tiny working circuits that allow us to function.
An injury has the effect of breaking these circuits.
This means the cells around the injured part must take on some of the duties that had been carried out by the injured part.3
Like any of us when we have to do something extra on top of our existing workload, it can make everything slower and less efficient.
One of the clinicians who we work with says it’s like the M25 when part of it is shut down.
If part of the M25 is out of action, then the traffic would stop entirely at first.
But slowly, drivers would head off in different directions and find new ways of getting back to the M25 and continuing along their route.
This is very much how the brain is sometimes able to respond to injury.4
The brain must find other routes – other ways of carrying out its functions – and this can take time.
When it’s injured
What follows is a whistle-stop tour of the brain, and the way different parts, or ‘regions’ influence our lives.
These parts work together for complicated activity such as speech or movement.
So if one part of the process is injured, the whole of the process is affected.
It’s almost like a premiership football team, in that if one key player has an injury, the whole team’s performance is affected.
Some injuries and their effects will be more widespread and so will affect several parts of the brain. These are called ‘diffuse’ injuries.
The different parts of the brain and what they do
The brain is divided into different areas, known as lobes.
The frontal lobesThe frontal lobes sit behind our forehead and are one of the biggest parts of the brain. The pre-frontal cortex, located here, looks after what are often called ‘executive functions’. As their name suggests, these are things like our judgement, decision-making, planning ahead, what we choose to focus our attention on, and the control of our behaviour and emotions.5, 6 This sophisticated part of the brain ‘overrides’ and keeps in check our more basic impulses and behaviours. It also plays a large role in speech and language, and in memory. And within the pre-frontal cortex is the motor cortex. This is involved in the control of our planned movements (as opposed to involuntary ones).5
When they are injuredThis part of the brain is particularly prone to injury if there’s an impact to the head.7 This is because the impact doesn’t necessarily have to strike this part of the head for it to be affected. There are bony ridges at the front of the skull, so if there’s a blow to any part of the head, the brain may move around and become damaged as it comes into contact with these ridges. In some cases, swelling might mean the brain comes into contact with these ridges. Another reason this part of the brain is prone to difficulty is because it’s connected up to many other parts. If you look again at the important functions the frontal lobes are responsible for, you can get a good idea of how someone might be affected. A child may have more trouble making decisions, solving problems, doing things in a correct sequence (for example, getting dressed, getting ready for a lesson) or generating ideas.8, 9 Behaviour can be affected. Some children show more impulsive behaviour – they may do things without ‘thinking them through’.10, 11 For other children, the effect on their behaviour may seem the opposite. They may feel a loss of motivation or ‘drive’.12 Speech, language and memory13, 14 are also affected. Read our separate sections on:
The parietal lobesFound just behind the frontal lobes, the parietal lobes are the processing centre for a lot of the information that comes in from around the body. They help us with our perception and the way we make sense of the world. They contain the ‘primary sensory cortex’, which controls sensations, like touch, pain and whether something is hot or cold.
When they are injuredWhen this part of the co-ordination system is injured, someone’s ability to locate parts of their body and their ability to know where they are in relation to everything around them is affected. This part of the brain is also involved in the way we understand language, and so this can be affected if the parietal lobes are injured.15
Occipital lobeThe occipital lobe is where we process all the visual information that’s pouring in. It helps us to perceive different shapes and colours, faces and objects.
When it’s injured
Injury to this part of the brain can affect the way someone perceives size, shape and colour.16