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Looking inside the brain using MRI

A video exploring how MRI scans can help us understand the structures of normal brains.
The MRI scanner is used to see the soft tissues, the skin, fat, muscle and internal organs and allows researchers to take detailed pictures in three dimensions which show the structure of the brain. Here we see a subject being prepared for an MRI examination, which uses a very strong magnet (the circular or doughnut shaped structure) to take pictures of inside the body.
If I scan my brain here is what we see: On these images you can see my skull stripped away to reveal the living brain inside. The brain is composed of billions of cells which give the brain its ability to control our bodies, thoughts and feelings. These same cells give the brain its shape and structure. When we look down on my brain from above we see that it is formed from two halves, or hemispheres. Looking at the brain from the side, each half or hemisphere of the brain is divided into four further sections called lobes. Below the main brain structure is further single lobe called the cerebellum. Each of these lobes is responsible for different aspects of our brain function.
The temporal lobe contains parts of the brain responsible for our hearing and processing of sounds, key areas involved in language and speech and areas of the brain involved in memory. - The occipital lobe at the back of the brain receives signals from our eyes and is involved in vision and processing the information from our eyes. - The parietal lobe contains parts of the brain which control movement and processes input from our senses, and how we perceive the world about us - The frontal lobe is involved in planning and language - The cerebellum is important for helping coordinate movement and balance.
If an injury or disease causes damage to a lobe of the brain then some of the function of that lobe can be lost, depending on where the damage or disease occurs.
Now looking inside the brain, here we have stripped away the top of the head and are looking down into the brain.
We see three main types of features: - On the surface of the brain is a thin grey strip, between 3 and 10 mm in thickness, called the grey matter and sometimes also called the cortex. The cortex contains cells which are involved in the main parts of brain function. - Inside the cortex is the white matter which show up the brightest on this scan. The white matter contains cells which join together different parts of the cortex to create a dense network. - In the centre of the brain are the ventricles. These contain a fluid called the cerebro-spinal fluid or CSF.
The CSF is made in the ventricles and bathes the surface of the brain, filling the space between the brain and the skull to keep the brain stable inside the skull. We can also use MRI scans to follow the connections between the different parts of the cortex, which are called the white matter tracts. This scan shows these white matter tracts and reveals the complexity of the internal structure of the brain. The areas of the cortex can be thought of as being wired together into networks by the brain cells within these tracts.
If we damage this internal wiring of the brain by disease or injury then the functions of the brain networks will be affected and may also cause us to lose some aspect of our normal brain function. Let us now look at what happens to the brain as we age by comparing scans in different healthy people at different ages. These MRI scans show 4 people aged 25 years, 50 years, 60 years and 85 years old. We can see that every brain is slightly different in shape and size. But let us focus on the darkest grey areas in the images which contain the fluid CSF. These are the ventricles and the spaces around the outside of the brain.
The spaces (highlighted now in red) are larger in the oldest person showing that as part of normal ageing the brain is shrinking. We know that in older people, the ventricles increase in size and we also lose about 0.5 % of the cortex each year.
To understand what is happening in the brain and why this causes symptoms in an individual we must be able to look inside the skull.
In this video Professor Andy Blamire explains how healthy brains are structured and shows what happens to our brains as we age. The video uses images from magnetic resonance imaging (MRI) scans of Professor Blamire’s own brain. These don’t use radiation and are very safe. MRI scans can be used to help with diagnosis and are also important for research.
Note: In this video and the next Andy uses scans of real brains to illustrate his point. If you would prefer not to view this content you can click the View transcript button to read the content instead.
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