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Unlock This CourseThe brain controls everything we do, so when part of it is damaged, something we normally do without thinking can suddenly go wrong. A person might not be able to lift an arm, keep their balance or find the words they want to say.
Psychologists study these changes because they show what each part of the brain is for. If damage to one area always causes the same problem, that area probably does that job. This links to what you learned about localisation of function.
Key terms:
Brain cells need a constant supply of blood to bring them oxygen. In a stroke, the blood supply to part of the brain is cut off by a blockage, or a blood vessel bleeds. The brain cells in that area are starved or harmed and stop working. A stroke can happen suddenly, at any age, though it is more common in older people.
A hard blow to the head can bruise or tear brain tissue. Which problems follow depends on where the damage is. A blow to the front of the head may harm different abilities from a blow to the back.
In both cases the effects depend on where the damage is and how big it is. This is why two people with strokes can have very different problems.
Motor abilities are our skills at moving the body. Damage can make them worse in different ways.
The motor area sends the signals that make muscles move. If it is damaged, the person may have weakness or paralysis. Because of the crossing over of signals, damage to the left side of the brain affects the right side of the body, and the other way round.
The cerebellum helps balance and coordination. If it is damaged, the person may be unsteady on their feet and find smooth, controlled movements hard, such as picking up a cup without shaking.
So a person who has a stroke on the left of the motor area might find their right arm and leg weak and hard to use, even though their muscles are healthy. The muscles are fine. It is the brain signals to them that are damaged.
Damage can change how a person acts, thinks and speaks as well as how they move.
Damage can change personality. A calm, careful person may become short-tempered, careless or unable to plan ahead. They may find it hard to control their behaviour (self-control).
Damage to a language area can affect speech. After damage to Broca's area, speech can become slow and hard to produce. After damage to Wernicke's area, a person may speak easily but what they say makes little sense.
These changes can make work, school and relationships hard. The person is still the same human being, but how they act has changed because the brain has changed.
Remember, Phineas Gage and HM are famous cases where brain damage changed behaviour. This lesson is about the general pattern, so you do not need to retell their stories.
There is a limit, though. Every injury is different, and damage often covers more than one area, so it can be hard to say exactly which area caused which change.
(a) Describe what is meant by a stroke. [2 marks]
(b) Explain how damage to the motor area of the brain could affect a person's movement. [2 marks]
(c) Describe one way that frontal lobe damage could change a person's behaviour. [2 marks]
(a) A stroke is when the blood supply to part of the brain is blocked (1) or a blood vessel in the brain bleeds, which damages the brain cells there (1).
(b) Damage to the motor area could cause weakness or paralysis (1) on the opposite side of the body, because the signals that move the muscles cannot be sent properly (1).
(c) Frontal lobe damage could change the person's personality (1), for example making a calm person become short-tempered or unable to control their behaviour (1).
For 'explain' questions about damage, name the area, then say the effect, then link them: 'damage to the cerebellum affects balance because this area controls coordination'.