⚽ Cerebellum: smooth movement
Think about catching a ball or riding a bike. You need many muscles to work together at the right time. The cerebellum coordinates this so your movements are smooth, and it helps you stay balanced.
The Human Nervous System » The Brain
What you'll learn this session
Study time: 30 minutes
AQA spec: 4.5.2.2 (biology only)
- How the brain controls complex behaviour
- The cerebral cortex, cerebellum and medulla, and what each one does
- Higher tier: how scientists have mapped the brain
- Higher tier: why the brain is so hard to investigate and treat
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Unlock This CourseThe brain: the control centre
The brain is the control centre of your body. It is the main part of the central nervous system, and it decides how your body responds to what is going on around you.
The brain controls complex behaviour. That means much more than simple reflexes. It lets you think, remember a phone number, learn a language, plan your day, feel happy or worried, and play a musical instrument.
It can do all of this because it is made of billions of interconnected neurones. Each neurone connects with many others, so a huge network of pathways carries impulses around the brain. Different regions of the brain carry out different functions.
Key terms:
- Complex behaviour: actions that involve thinking, memory, learning and decisions, not just a quick reflex.
- Cerebral cortex: the wrinkled outer layer of the brain, used for the most advanced thinking.
- Cerebellum: the part at the back of the brain that coordinates movement and balance.
- Medulla: the part at the base of the brain that controls automatic body functions.
Three regions you must know
You need to be able to identify three regions on a diagram of the brain and describe what each one does.
🧠 Cerebral cortex
The folded outer layer at the top and sides of the brain. It is the largest part. It controls consciousness, intelligence, memory and language.
⚖ Cerebellum
A smaller, ridged region at the back, underneath the cortex. It controls coordination of movement and balance.
❤ Medulla
At the base of the brain, where it joins the spinal cord. It controls unconscious activities such as heart rate and breathing.
The cerebral cortex in more detail
The cerebral cortex is where your conscious thoughts happen. Being conscious means being aware of yourself and what is around you. When you read this sentence, understand it and remember it, your cortex is at work.
Four words are worth remembering for the cortex: consciousness, intelligence, memory and language. The deep folds of the cortex give it a large surface area, so there is room for a very large number of neurones.
Different areas of the cortex have different jobs. For example, some areas receive information from the senses, and other areas control movement.
The cerebellum and the medulla
😴 Medulla: automatic jobs
You do not have to think about your heart beating or breathing in and out. The medulla controls these unconscious activities, even when you are asleep. Without it, the body could not keep going.
Common mistakes
Do not say the cerebellum controls "thinking". That is the cerebral cortex. Do not say the medulla controls "movement". It controls unconscious activities such as heart rate and breathing. The cerebellum coordinates movement.
Higher tier only: how do we know what each part does?
Higher tier only
Neuroscientists have been able to map the regions of the brain to particular functions. They did this in three main ways.
1. Studying patients with brain damage. If a person has damage to one area and loses a certain ability, such as speech or movement in one arm, that area must be involved in that function.
2. Electrically stimulating different parts of the brain. A small electrical current is applied to part of the brain. The scientists then see what the person does or feels, such as a finger twitching, and so link that area to that function.
3. MRI scanning. An MRI scanner produces images of the inside of the brain. Scientists can see the structure of the brain and which regions are active when a person does a task, without opening the skull.
Higher tier only: why is the brain so hard to investigate and treat?
Higher tier only
The complexity and delicacy of the brain makes investigating and treating brain disorders very difficult.
- It is very complex. There are billions of interconnected neurones, and many regions work together, so it is hard to work out what causes a problem.
- It is delicate. Damaging even a small number of neurones during a procedure can change how a person thinks, speaks or moves.
Higher tier only: benefits and risks of procedures on the brain
Higher tier only
You may be asked to evaluate the benefits and risks of a procedure carried out on the brain or nervous system. Weigh up both sides.
Possible benefits: a treatment could ease or cure a brain disease or disorder, and stimulation and scanning help scientists learn more about the brain.
Possible risks: a procedure may damage healthy parts of the brain, it may not work, and the patient could lose an ability they had before.
A good answer says which side matters more for the person in the question and gives a reason.
Worked example: matching damage to the region
Worked example
A person has a head injury. Afterwards they can walk, but their movements are jerky and they often lose their balance. Their heart rate and breathing are normal. They remember their friends and can talk normally.
Step 1: Heart rate and breathing normal, so the medulla is working.
Step 2: Memory and language normal, so the cerebral cortex is working.
Step 3: Jerky movement and poor balance points to damage to the cerebellum.
Exam-style question
(a) Name the part of the brain that controls heart rate and breathing. [1 mark]
(b) Describe two functions of the cerebral cortex. [2 marks]
(c) Higher tier only: a scientist electrically stimulates part of a patient's brain and the patient's hand moves. Explain how this helps the scientist to map the brain. [2 marks]
Model answer
(a) The medulla (1)
(b) Any two from: consciousness, intelligence, memory, language (1 each)
(c) Higher tier only: the area stimulated must control movement of the hand (1), so the scientist can link that region of the brain to that function (1)
Exam tip
In part (b) the question says "two functions", so give exactly two, one per mark. Use the key words: consciousness, intelligence, memory and language.