Main parts of the brain
- Cerebrum: the largest part. It is split into a left and a right hemisphere. Its wrinkled outer layer, the cerebral cortex, does thinking, language, senses and planned movement.
- Cerebellum: "little brain" at the back and bottom.
- Brain stem: joins the brain to the spinal cord. It controls automatic jobs like breathing, heartbeat and sleep.
Each hemisphere controls the opposite side of the body. The left motor area moves the right hand.
The four lobes and the cerebellum
| Part | Where | Main jobs |
|---|---|---|
| Frontal lobe | Front | Planning, decisions, personality, starting movement (motor area), producing speech (Broca's area) |
| Parietal lobe | Top, behind frontal | Touch, pain, temperature (somatosensory area), sense of body position |
| Temporal lobe | Sides, near ears | Hearing (auditory area), understanding language (Wernicke's area), memory |
| Occipital lobe | Back | Vision (visual area) |
| Cerebellum | Back, under the cerebrum | Balance, posture, smooth and well-timed movement |
Damage gives clues. A person with frontal damage may plan badly or change personality. Cerebellum damage causes poor balance and clumsy movement.
Localisation of function and Penfield's study
Localisation of function means that particular jobs are controlled by particular areas of the brain.
- Motor area (back of frontal lobe): sends signals to move muscles.
- Somatosensory area (front of parietal lobe): receives touch from the skin.
- Visual area (occipital lobe) and auditory area (temporal lobe).
- Language areas, usually in the left hemisphere: Broca's area (frontal) for producing speech and Wernicke's area (temporal) for understanding it.
Penfield's study
Wilder Penfield, a surgeon, operated on people with severe epilepsy. Because the brain feels no pain, patients stayed awake with only local anaesthetic. He touched the cortex with a weak electric probe and asked what they felt.
- Touching the somatosensory area made patients feel tingling in a body part.
- Touching the motor area made a body part twitch.
- Some temporal lobe points brought back sounds or memories.
He mapped the body onto the cortex. Body parts with fine control or feeling, like the hands and lips, have far more cortex than the back or legs. Limits: patients had epilepsy, so their brains may not be typical, and reports were based on what patients said.
Cognitive neuroscience: brain scanning
Cognitive neuroscience studies how brain structures produce thinking, memory and other mental processes. Scans let us study living brains without surgery.
| Scan | How it works | Shows |
|---|---|---|
| CT | Many X-ray images from different angles | Structure: tumours, bleeds, damage |
| PET | A small dose of radioactive sugar; busy areas use more | Activity, in colour |
| fMRI | Strong magnets detect oxygen-rich blood going to busy areas | Activity, very detailed, no radiation |
Strengths: they show the real living brain and help doctors. Limits: scanners are costly; PET uses radiation; lying still in a loud machine is not real life.
Tulving's gold memory study
Endel Tulving wanted to see if different kinds of long-term memory use different brain areas.
- A small group of volunteers (including Tulving himself) was injected with a safe radioactive gold tracer and given PET scans.
- They thought about either episodic memories (personal events, like a holiday) or semantic memories (facts, like capital cities). Each person did several trials.
- Result: episodic memories caused more activity at the front (frontal lobe); semantic memories caused more activity towards the back.
Conclusion: memory has a physical basis and different kinds are localised. Limits: only six people took part, and not all of them showed clear results. Episodic and semantic memories are also hard to separate.
Try it
In the free play, tap each part and say its job aloud before you read it. Then try this: stand on one foot with eyes closed for 20 seconds. Which part of your brain is working hardest? (Hint: the one at the back and bottom.)
Key formulas and definitions
- Cerebrum (2 hemispheres, cortex) · cerebellum · brain stem
- Frontal: plan, move, speak (Broca) · Parietal: touch · Temporal: hear, understand (Wernicke), memory · Occipital: see
- Cerebellum: balance and coordination
- Localisation: particular job → particular area (Penfield's stimulation maps)
- CT = structure · PET, fMRI = activity · Tulving: episodic → front, semantic → back
Worked examples
1. After an injury at the back of her head, Meena can think and speak normally but cannot see. Which lobe was damaged?
The occipital lobe, at the back of the brain, which contains the visual area.
2. A man has a stroke and can understand speech but struggles to say words. Which area is likely damaged, and in which lobe?
Broca's area, in the frontal lobe (usually on the left). It produces speech; understanding needs Wernicke's area, which is working.
3. A doctor wants to see which part of the brain becomes active when a patient reads. Should she use CT or fMRI? Why?
fMRI. CT shows only structure. fMRI shows activity by tracking oxygen-rich blood flowing to busy areas, without radiation.
Common mistakes
- Saying the occipital lobe is at the front. It is at the back and handles vision.
- Mixing up Broca (producing speech, frontal) and Wernicke (understanding speech, temporal).
- Thinking a CT scan shows brain activity. It shows structure; PET and fMRI show activity.
- Saying the left brain controls the left side of the body. Each side controls the opposite side.