The science behind the scenes - A window on the brain

Humans have always been fascinated with how the mind works. How can a unique ‘you’ with memories, thoughts and feelings be created by the activity of 100 billion neurons (or nerve cells) in the brain? And what happens in the brain when people suffer from mental illness, or from diseases like Alzheimer's?

Neuroscientists study how the brain processes information and how illness affects brain function, because this is the key to understanding the link between the mind and health. In essence, your brain is the boss of your body.

How to take a picture inside your skull!

Researchers working in the area of neuroscience are making discoveries all the time, and this has been helped by the technology and the science behind the techniques they use to make images of the brain. 

There are two main ways of ‘taking pictures’ of the brain – structural imaging and functional imaging.

• Structural imaging creates an image of the entire brain. It allows scientists to view large-scale brain injury or diseases, such as brain tumours.
• Functional imaging is used to study the brain in action. Using this type of imaging allows scientists to pinpoint the areas of the brain that are responsible for different thoughts, feelings, decisions and behaviour. For example, a functional image could be taken of the areas of the brain that are active when a person is talking.

A method known as magnetic resonance imaging (MRI) is used in both structural and functional imaging. Molecules that are found within the body (biological molecules) have magnetic properties, and MRI makes use of these magnetic properties to show where molecules are concentrated within the brain. For example, when a region of the brain is active, blood flow to this region increases because extra oxygen is needed. Functional MRI (fMRI) creates a picture of these active regions.

What does the brain do and how does it do it?

Our brain is the most complex but least understood organ in our body. It controls all our body’s activities, from breathing and listening to thinking and moving. How do you remember your way to your friend’s house? How do you blink and breathe without thinking about it? The brain does all this and much more.

The main parts of the brain are the brain stem, cerebellum and the cerebral cortex.

The brain and spinal cord make up what is called the central nervous system. The spinal cord consists of neurons that carry messages from the brain to all other areas of the body, and back again.

The cerebral cortex is divided into two parts called hemispheres. Generally, the left hemisphere controls the right side of your body and the right hemisphere controls the left side. Therefore people who are right or left handed will have slightly different brains from each other. In addition, each hemisphere manages different tasks. In right-handed people, for example, language is mainly processed in the left side of the brain.

The brain is made up of two main types of cell – neurons (or nerve cells, which are also found throughout the body) and glial cells. About 10 per cent are neurons, which communicate with each other by passing chemical and electrical signals. The glial cells provide physical support, protection and the nutrients the neurons require to stay healthy and functioning.

Each neuron has:

• A cell body – containing the cell’s genetic information
• Dendrites – which receive information from other neurons
• An axon – which is the long fibre linking one neuron to another, in the brain or spinal cord. Axons are often coated in a myelin sheath, which is a protein and fat layer that allows electrical impulses to travel as quickly as possible down the neuron.
   

Why is this important?

Go to main page of Teacher's Resource - A window on the brain

View this information in printable format.

With thanks to the MRC for supplying the images for this resource.