HookAn iron rod went through his skull — and changed psychology forever
On 13 September 1848, a 25-year-old railway foreman named Phineas Gage was packing explosive into rock in Vermont when the charge went off early. A metre-long iron tamping rod shot upwards, entered under his left cheekbone, passed straight through the front of his brain and landed some twenty metres away. Astonishingly, Gage sat up within minutes and spoke. He lived another twelve years. But the man who walked away was not the man who had arrived that morning. The reliable, well-liked foreman became impulsive, foul-mouthed and unable to hold down a job — 'no longer Gage', his friends said. His body was intact; the damage was to who he was.
Gage is where this whole topic begins, because his case hinted at an idea that took another century to prove: that specific mental functions — planning, self-control, personality — live in specific parts of the brain. This section builds that picture from the wiring up. You will meet the nervous system that carries every signal, the neurons and synapses that pass messages one cell to the next, the lobes of the brain that Gage's rod first mapped by accident, and the modern scanning studies that now let us watch a living brain think. The thread running through all of it is localisation of function — the idea Gage's damaged frontal lobe first whispered.
ModelThe nervous system — and the fight or flight response
Your nervous system is the body's electrochemical communication network, and AQA wants you to split it two ways. The central nervous system (CNS) is the brain and the spinal cord: the brain is the seat of consciousness, decision-making and processing, while the spinal cord relays messages between the brain and the body and controls fast reflexes. Branching out from the CNS is the peripheral nervous system, and within it the part the exam cares about most — the autonomic nervous system (ANS), which runs automatic functions you never consciously choose, such as heart rate, breathing and digestion.
The ANS has two opposing branches. The sympathetic branch arouses the body for action; the parasympathetic branch calms it back down, which is why it is nicknamed 'rest and digest'. The star of the topic is what the sympathetic branch triggers under threat: the fight or flight response. When you perceive danger, the hypothalamus signals the sympathetic branch, which tells the adrenal glands to flood the bloodstream with adrenaline. Adrenaline raises heart and breathing rate, dilates the pupils, diverts blood to the large muscles and releases stored glucose for energy — all in seconds, preparing you to confront the threat or run from it. Once the danger passes, the parasympathetic branch reverses the changes and returns the body to rest.
MechanismNeurons and the synapse — how a message crosses the gap
Messages travel through the nervous system as electrical impulses carried by cells called neurons, and AQA names three types by the job they do. Sensory neurons carry impulses from sensory receptors — in the eyes, skin, ears — towards the CNS. Relay neurons sit inside the CNS and connect one neuron to another, linking sensory input to motor output. Motor neurons carry impulses from the CNS out to effectors, the muscles and glands that actually produce a response. A single neuron has dendrites that receive signals, a cell body, and an axon — often wrapped in a fatty myelin sheath that insulates it and speeds the impulse along — ending in terminals that pass the signal on.
The clever part is what happens between two neurons. They do not touch. At the synapse there is a tiny gap, the synaptic cleft, and the electrical impulse cannot jump it. Instead, when the impulse reaches the end of the first (presynaptic) neuron, it releases chemical messengers called neurotransmitters, which diffuse across the gap and bind to receptors on the next (postsynaptic) neuron — turning the message chemical, then back into electrical. Neurotransmitters come in two flavours the exam tests: excitatory ones (such as adrenaline) increase the chance the next neuron fires, while inhibitory ones (such as serotonin) decrease it. Whether a neuron fires depends on the balance of the two — a detail that returns when you study depression and its serotonin imbalance in the next section.
Here is a 4-mark application question and a model answer, annotated so you can see exactly where the marks are earned.
Question: 'Maria is walking home at night when a large dog runs at her, barking. Her heart pounds and she sprints to safety. Using your knowledge of the nervous system, explain Maria's reaction.' (4 marks)
Model answer: 'When Maria sees the dog as a threat, her sympathetic branch of the autonomic nervous system is activated and triggers the fight or flight response [this is the AO1 knowledge — the named system and response]. This causes her adrenal glands to release adrenaline into her bloodstream, which raises her heart rate — the pounding she feels — and diverts blood and glucose to her leg muscles, which is what lets her sprint away [this is the AO2 application — each bodily change is tied directly to Maria's pounding heart and her running]. Because flight, not fight, is the safer option against a large dog, her body has prepared her to escape rather than confront it [this closes by applying the fight-versus-flight choice to her exact situation].'
Notice the shape: name the system, then bolt every physical symptom in the stem — the pounding heart, the sprint — back onto the biology. The classic way to lose marks here is to describe fight or flight perfectly but never mention Maria, the dog or the specific symptoms — that is AO1 floating free of the AO2 the question actually demanded.
CaseThe map of the brain — lobes and localisation
The outer, folded surface of the brain — the cerebral cortex — is divided into four lobes, and AQA expects you to name each and its main job. The frontal lobe handles thought, planning, decision-making, personality and voluntary movement; it is the region Phineas Gage's rod destroyed, which is why his self-control and character collapsed while his senses and movement survived. The parietal lobe processes sensory information such as touch, temperature and pain. The occipital lobe, right at the back, processes vision. The temporal lobe, at the sides, processes hearing and contributes to understanding language and memory.
Beneath the lobes sits the cerebellum ('little brain'), which coordinates movement, balance and posture — damage to it produces clumsy, jerky movement and difficulty balancing, not a change in personality. Together these regions illustrate the topic's central idea, localisation of function: the claim that different mental and physical functions are handled by specific, identifiable areas rather than by the brain as an undivided whole. Gage was the accidental first evidence for it; the studies in the next block are the deliberate, modern proof.
DataNeuropsychology — scanning a living brain at work
Cognitive neuroscience is the scientific study of how the brain's structures produce mental processes such as memory, perception and attention — in effect, linking the biology of the lobes to the thinking they generate. For most of history this was guesswork, because you could only study a brain after death or after injury like Gage's. The field was transformed by brain-scanning techniques. A CT (CAT) scan uses X-rays to build a detailed structural picture, good for spotting tumours or damage but showing shape, not activity. A PET scan tracks a radioactive glucose tracer to reveal which regions are metabolically active during a task. An fMRI measures changes in blood flow and oxygen to show active areas in real time, without radiation — now the workhorse of the field.
AQA names two studies you must know. Wilder Penfield's study of the interpretive cortex stimulated the exposed brains of conscious epilepsy patients with a weak electrical current during surgery; when he touched the temporal lobe, patients reported vivid flashbacks — sounds, smells and scenes from their past — suggesting that area interprets and stores experience. Endel Tulving's 'gold' memory study injected volunteers with a radioactive gold isotope and used PET scans while they recalled two kinds of memory: episodic (personal events) and semantic (general facts). The two types produced different blood-flow patterns in different regions, supporting the idea that distinct memory types are localised in distinct parts of the brain — the same localisation principle, now proven with a scanner rather than an iron rod.
VocabularyKey terms the mark scheme pays for
TrapsMisconceptions that cost marks
ExamWhat examiners want
Brain and neuropsychology questions in AQA GCSE Psychology (8182) reward precision with biological vocabulary, so learn the labels exactly: it is the sympathetic branch that triggers fight or flight, the adrenal glands that release adrenaline, and the occipital lobe (not the temporal) that handles vision. AO1 questions ask you to describe structures and studies — practise sketching or listing the four lobes with one function each, and revise Penfield and Tulving with what each actually showed about localisation. AO2 gives you a scenario — someone startled, someone with damage to a named lobe — and expects you to apply the right structure to that person, tying each symptom in the stem back to the biology rather than reciting the theory in the abstract.
AO3 evaluation on this topic has reliable currency worth banking. Case studies like Gage are vivid but based on a single, unusual individual, so they are hard to generalise from. Scanning techniques differ in useful ways you can contrast: CT and PET involve radiation whereas fMRI does not, and structural scans show damage while functional scans show activity — a comparison examiners love. On extended-response questions worth 6 or 9 marks, use a levels-based approach: make a point, support it with a named study or structure, evaluate it, and answer the exact wording rather than emptying everything you know onto the page.