brain tour
  • Personality
  • Memory
  • Ordering
  • Emotions
  • Vision
  • Language
  • Body
  • Spatial
  • Behaviour

The Human Brain

Brain Tour

Click the hotspots to discover how your brain works and the effect dementia has on it.

Join us on a tour of the brain, the most complex structure in the known universe. From movement to memory, find out what different parts of the brain do, and how they can be affected by dementia.

Alzheimer's Research UK scientists learn more about the brain and dementia every day and the Brain Tour showcases our progress. With hundreds of projects underway looking at causes, diagnosis and treatment, you are helping us bring about breakthroughs to change lives.

What it does

Enclosed by the tough protective casing of the skull, our brains are the centre of our nervous systems. The brain monitors and regulates our actions and reactions. It constantly receives information from our senses, rapidly analysing and co-ordinating our responses to things we see, hear, touch and taste.

The brain is also our centre of learning. It forms and stores our memories. It's involved in speech, abstract thought and consciousness as well as informing our personality and emotions. An adult brain weighs about 1.5kg (3.3lb) and contains about 90 billion nerve cells. As well as nerve cells our brains have about 90 billion other cells, plus blood vessels to help supply the nutrients and oxygen it needs. During dementia, nerve cells in different areas of the brain become damaged and eventually die. A lot of research we're supporting aims to stop this damage and protect the brain from harm.


What it does

The largest part of our brain, the cerebrum plays a role in memory, attention, thought, language and consciousness. It's also involved with our senses and movement.

It's made up of tightly folded grey matter, giving the brain its wrinkly look, and white matter, which is made of bundles of fibres that transport information - like bundles of electrical wires.

How it's affected

Dementia with Lewy bodies (DLB) affects the cerebrum. In DLB small, round lumps of proteins build up in the grey matter. These spheres harm nerve cells, causing the symptoms of DLB including hallucinations and fluctuations in consciousness.

This area can also be affected by vascular dementia, the second most common cause of dementia after Alzheimer's. Vascular dementia is caused by blood flow to the brain being reduced. Blood carries essential oxygen and nourishment to the brain and without it brain cells die.

Frontal lobe

What it does

The frontal lobe is involved with our personality, behaviour and emotions.

It's involved in choosing between good and bad actions as well as predicting the consequences of our actions. It suppresses unacceptable social behaviour. It helps us decide on similarities and differences between things. It is also involved in storing long-term memories.

How it's affected

Frontotemporal dementia (or FTD) affects this area of the brain.

There are different types of frontotemporal dementia. Some affect the frontal lobes early on and patients behave inappropriately and often experience personality changes. It's thought that frontotemporal dementia is caused by proteins building up in the brain, harming nerve cells.

Parietal lobe

What it does

The parietal lobe helps us put things in order - like letters when we are reading and writing, and numbers in a calculation.

It is responsible for our 'body sense' e.g. knowing where our arms and legs are in relation to the rest of our bodies. It also helps us see, recognise and locate objects in three dimensions e.g. so we can pick things up.

How it's affected

This part of the brain is affected by posterior cortical atrophy (PCA) a rare type of Alzheimer's.

Because this part of the brain helps us see, when it becomes damaged in PCA patients experience difficulties seeing what and where things are. Like in the more common form of Alzheimer's disease, it's affected by proteins building up and damaging nerve cells.

Temporal lobe

What it does

The temporal lobe helps us understand things we see and hear around us. It's involved with remembering and recognising faces, objects and scenes. It is also involved in language, including naming things and remembering words.

The temporal lobe has a role in memory too - including memories of things that have happened to us. Inside the temporal lobe is an area called the hippocampus. The hippocampus makes new memories and helps us find our way, remembering places and layouts.

How it's affected

The hippocampus is affected by Alzheimer's disease.

Two proteins, amyloid and tau, build up and damage nerve cells. This build up starts in the hippocampus before spreading to other brain areas. The damaged nerve cells in the hippocampus mean this part of the brain can’t function properly, which can lead to the early symptoms of Alzheimer’s – memory loss and disorientation. The temporal lobe is affected by frontotemporal dementia, a rare type of dementia. There are different types of frontotemporal dementia. Some affect the temporal lobes early on and those affected have problems with language, speech and factual knowledge about the world.

Occiptal lobe

What it does

The occipital lobe interprets information from our eyes.

It determines the shape, colour and movement of the things we are looking at. It also produces the dreams we experience when we sleep.

How it's affected

This area of the brain is affected by a rare form of Alzheimer's called posterior cortical atrophy (PCA).

Because this part of the brain helps us see, when it becomes damaged in PCA, people can experience difficulties seeing where and what things are. Like in the more common form of Alzheimer's disease, it's affected by proteins building up and damaging nerve cells.


What it does

The cerebellum helps control our movements, including balance and posture. It's also involved in attention and language.

How it's affected

Like other areas of the brain, the cerebellum is eventually affected by Alzheimer's and other dementias.

Most dementias are 'progressive', which means they get worse over time. People's symptoms get worse as nerve cells become damaged in more and more areas of the brain. The two hallmark Alzheimer's proteins build up in this area and damage nerve cells.

Nerve cells, proteins, plaques & tangles

nerve cells

Nerve cells

Our brains have about 90 billion nerve cells. They are specialised in sending messages to each other. They allow us to sense and respond to the world around us.

During dementia, cells lose the ability to communicate with each other and eventually die. This loss of nerve cells causes the symptoms of dementia, for example memory loss, as the brain becomes unable to function in its usual way. What causes nerve cells to die in dementia is a hot topic for our research. Our scientists are finding out more every day about how we can protect brain cells from harm, moving us closer to new dementia treatments. Nerve cells have a body or hub and many long, thin branches (axons and dendrites) that extend from the body. These reach out to other nerve cells. The points where nerve cells connect to each other are called synapses. Nerve cells use both tiny electrical impulses and specialised chemicals to send messages to each other.

protein cells

Proteins, plaques & tangles

Proteins are a vital part of our bodies. They have thousands of jobs to do. Different proteins make up our skin, hair and bones. Other proteins move our muscles or digest our food.

There are different diseases that can cause dementia, including Alzheimer's disease, dementia with Lewy bodies and frontotemporal dementia. These share a common feature - an excessive build up of proteins in the brain. In Alzheimer's there are two culprit proteins, called amyloid and tau. They build up during the disease, become toxic and harm the brain and nerve cells. Amyloid makes sticky clumps or 'plaques' where as tau forms tangles, twisting inside cells and blocking them. In dementia with Lewy bodies (DLB), the culprit is a protein called 'alpha-synuclein'. It forms tiny spheres which are toxic. During frontotemporal dementia several different proteins can build up. We're supporting a lot of research looking at ways to stop these proteins from building up and causing harm.