Brain trauma and neurological disorders: acquired brain injury, aphasia and recovery (QCE Psychology Unit 3)
“Appreciate how plasticity assists in the recovery from brain injury”
Acquired brain injury (ABI) is brain damage occurring after birth, either traumatic (a blow, as in concussion) or non-traumatic (stroke, tumour, infection). Because functions are localised, damage produces predictable deficits: frontal damage alters personality and executive function, left-hemisphere language area damage causes aphasia, hippocampal damage causes amnesia. Recovery depends on neuroplasticity, where surviving neurons reroute and reorganise, supported by rehabilitation that drives this rewiring.
Jump to a section
In the QCAA Psychology 2025 syllabus, recovery from brain injury appears in Unit 3 Topic 1 (Brain function) as science as a human endeavour subject matter, which may be assessed in the internal assessments but not the external assessment. Neural plasticity and brain damage are also Unit 1 Topic 2 subject matter. The examinable Unit 3 disorders are Parkinson's disease and Alzheimer's disease, as examples of interference in neurotransmitter function.
What this dot point is asking
QCAA wants you to explain how damage to the brain, whether through injury or disease, disrupts individual thinking, and to connect specific damaged regions to specific cognitive and behavioural changes. You then need to explain how the brain attempts to recover through neuroplasticity and rehabilitation. This dot point applies the principles of localisation and plasticity to real disruptions of cognition.
The answer
Brain trauma and neurological disorders show what happens when the structures behind individual thinking are disrupted. Because particular functions are localised to particular regions, the location of damage predicts the kind of deficit, which is why these cases also provide evidence for localisation.
Types of acquired brain injury
Acquired brain injury (ABI) refers to any brain damage that occurs after birth, as opposed to congenital conditions. It is divided into two types.
- Traumatic brain injury (TBI). Caused by an external physical force, such as a blow to the head in a fall, car accident or contact sport. Concussion is a mild TBI; severe TBI can involve bleeding, swelling and widespread axonal damage.
- Non-traumatic (internal) brain injury. Caused by internal events such as a stroke (interrupted blood supply), tumour, infection (encephalitis), oxygen deprivation, or a degenerative disease such as Alzheimer's.
How damage disrupts cognition
Specific deficits follow from the function of the damaged region, illustrating localisation in reverse.
- Frontal lobe damage disrupts executive function, planning, impulse control and personality, as in the historical Phineas Gage case.
- Damage to Broca's area (left frontal) produces Broca's aphasia: speech is non-fluent and effortful but comprehension is largely intact.
- Damage to Wernicke's area (left temporal) produces Wernicke's aphasia: speech is fluent but meaningless and comprehension is impaired.
- Hippocampal damage produces amnesia, especially the inability to form new long-term memories (anterograde amnesia), as in the famous patient HM.
- Right parietal damage can cause spatial neglect, where the person ignores the left side of space.
Neurological disorders
Neurological disorders are diseases of the nervous system that progressively or suddenly impair cognition. Examples include Alzheimer's disease, which degrades memory through neuronal loss in the hippocampus and cortex; Parkinson's disease, which affects movement through loss of dopamine-producing neurons; and epilepsy, where abnormal electrical activity can disrupt consciousness and, in severe cases, has historically been treated by severing the corpus callosum (producing split-brain patients).
Recovery through neuroplasticity
The brain is not fixed, and after injury it attempts to recover function through neuroplasticity, the same mechanism that supports learning.
- Rerouting and sprouting. Surviving neurons grow new connections and take over functions previously handled by damaged tissue.
- Reorganisation. Other, undamaged regions can adopt the lost function, especially in younger brains.
- Recovery of dormant tissue. As swelling subsides, areas that were temporarily suppressed (in a state called diaschisis) can resume working.
Recovery is generally greater when the injury occurs early in life and is supported by intensive, repeated practice through rehabilitation. Constraint-induced movement therapy, for instance, forces use of an affected limb to drive plastic rewiring.
Acquired brain injury is split into traumatic (external force, such as concussion) and non-traumatic (internal cause, such as stroke). Recovery relies on neuroplasticity through sprouting, rerouting and reorganisation, and rehabilitation works precisely because repeated, effortful practice strengthens the surviving connections that take over lost functions.
Putting it together for an exam
A strong answer names the type of injury, links the damaged region to the specific deficit using a named example, and explains recovery through a named plastic mechanism. For example: a stroke (non-traumatic ABI) damaging Broca's area causes non-fluent aphasia, and rehabilitation supports recovery as surviving neurons sprout new connections that gradually take over speech production.
- Calling all brain injury traumatic
- Traumatic means an external force; strokes, tumours and infections are non-traumatic acquired brain injuries.
- Swapping the aphasias
- Broca damage gives non-fluent speech with intact comprehension; Wernicke damage gives fluent but meaningless speech with poor comprehension.
- Saying the brain cannot recover
- Neuroplasticity allows real recovery through rerouting and reorganisation, especially in younger brains and with rehabilitation.
- Forgetting rehabilitation drives plasticity
- Recovery is not automatic; repeated, effortful practice is what strengthens the new connections.
Exam-style questions
Questions in the style of QCAA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Practice1 markFollowing a car accident, a person is uncoordinated and walking unsteadily. Identify the area of the brain that is most likely damaged.Show worked answer →
The cerebellum (1 mark).
The car accident is a traumatic acquired brain injury. The cerebellum, at the rear base of the brain, coordinates voluntary movement, balance and posture, so damage to it produces uncoordinated movement and an unsteady, staggering gait (ataxia). The specific deficit points to the damaged region, illustrating localisation of function in reverse.
Practice2 marksDescribe a function of the cerebellum in memory and identify a relevant problem associated with cerebellum damage.Show worked answer →
Function (1 mark): the cerebellum supports procedural (implicit) memory, the storage and execution of learnt motor skills and habits, such as riding a bike or a conditioned movement, which is acquired through practice rather than conscious recall.
Problem from damage (1 mark): cerebellum damage impairs procedural memory and motor learning, so the person struggles to acquire or perform smooth, coordinated skilled movements and may show poor balance and clumsy, uncoordinated actions. Acquiring new motor skills becomes slow and inaccurate.