HookThe railway foreman who lost his frontal lobe and kept walking
On 13 September 1848, a 25-year-old railway foreman named Phineas Gage was packing explosive into rock when the charge went off early and drove a metre-long tamping iron clean through his skull — in under his left cheekbone, out through the top of his head, landing yards behind him. He did not die. He did not even lose consciousness for long; within minutes he was talking, and weeks later he was walking. But the calm, dependable foreman his employers had trusted was gone. In his doctor's famous phrase, Gage 'was no longer Gage' — now impulsive, profane and unable to hold down a job. A rod through the frontal lobe had changed his personality while leaving his movement and speech intact, and in doing so it hinted at an idea that organises this entire topic: specific parts of the brain do specific jobs.
Biopsychology is the study of behaviour as biology — the physical machinery that produces every thought and feeling. AQA builds it from the ground up: the wiring diagram of the nervous system, the individual neurons and the chemical synapses that pass signals between them, the slower endocrine system of hormones, and their dramatic collaboration in the fight-or-flight response. Then it scales up to the whole brain — which functions are localised where, how the two hemispheres divide labour, and how the brain rewires itself after damage — before turning to the tools that let us see inside a living brain and the biological rhythms that clock our days. It is the most factual topic in the specification, and its marks reward precision: name the gland, the neurotransmitter, the brain area, the study.
ModelThe nervous system — the body's electrical wiring diagram
The whole nervous system splits into two, and the split is the exam's favourite starting point. The central nervous system (CNS) is the brain and spinal cord — the brain is the centre of conscious awareness and control, and the spinal cord relays messages to and from it and governs reflexes. The peripheral nervous system (PNS) is everything else: all the nerves that carry messages between the CNS and the rest of the body.
The PNS then divides again. The somatic nervous system carries sensory information in from the senses and motor commands out to the skeletal muscles — it governs voluntary movement. The autonomic nervous system (ANS) runs the involuntary, automatic processes — heartbeat, digestion, stress responses — and has two opposing branches: the sympathetic branch, which arouses the body for action ('fight or flight'), and the parasympathetic branch, which calms it and conserves energy ('rest and digest'). Draw the tree once — CNS/PNS, then somatic/autonomic, then sympathetic/parasympathetic — and any labelling or 'identify the division' question falls straight out.
MechanismNeurons and the synapse — how a signal jumps the gap
Signals travel along three types of neuron. Sensory neurons carry impulses from receptors (eyes, skin) towards the CNS; relay neurons connect neurons to one another inside the CNS; motor neurons carry commands from the CNS out to effectors such as muscles and glands. A neuron fires by an electrical action potential that sweeps down the axon (insulated by a fatty myelin sheath that speeds transmission) to the terminals at its end.
But neurons do not touch — between them is a tiny gap, the synapse, which the electrical signal cannot cross, so transmission goes chemical. The arriving impulse triggers the release of neurotransmitters from vesicles; these diffuse across the gap and bind to receptors on the next neuron, then are reabsorbed (reuptake). Crucially, the effect can be excitatory (e.g. adrenaline makes the next neuron more likely to fire) or inhibitory (e.g. serotonin makes it less likely). Whether a neuron actually fires depends on summation — the net balance of all the excitatory and inhibitory signals arriving at once. That balance, computed billions of times a second, is the physical basis of everything the brain does.
ModelThe endocrine system — the slow chemical post
Running alongside the fast electrical nervous system is the slower endocrine system, which communicates through hormones released into the bloodstream by glands. Where a nerve impulse acts in milliseconds and is gone, hormones act more slowly but their effects are widespread and longer-lasting. The pituitary gland, in the brain, is the 'master gland' — it releases hormones that direct the other glands, coordinating the whole system.
The key glands to name: the adrenal glands (on top of the kidneys) release adrenaline and cortisol for stress; the thyroid releases thyroxine, controlling metabolism; the testes and ovaries release testosterone and oestrogen. The system and the nervous system work together — the clearest example being fight or flight, where the brain, the ANS and the endocrine glands act as one coordinated chain. A common exam ask is simply to contrast the two systems: nervous is fast, electrical and short-lived; endocrine is slower, chemical, bloodstream-borne and enduring.
MechanismFight or flight — the body's emergency broadcast
When you perceive a threat, an acute stress response floods the body for action, and AQA wants the pathway in order. The hypothalamus detects the stressor and activates the sympathetic branch of the autonomic nervous system. This triggers the adrenal medulla (the inner part of the adrenal gland) to release adrenaline into the bloodstream. Adrenaline is the agent of the physical changes you feel within seconds: increased heart rate and blood pressure (pumping oxygenated blood to the muscles), faster breathing, dilated pupils, and the diversion of energy away from digestion — all preparing the body to fight the threat or flee it.
Once the threat passes, the parasympathetic branch takes over and returns the body to its resting 'rest and digest' state, slowing the heart and restoring normal function — the classic biological example of the two ANS branches acting as antagonists. Evaluation the examiner rewards: the 'fight or flight' label is criticised as androcentric, because Taylor and colleagues argued females may show a 'tend and befriend' response instead, protecting offspring and forming alliances rather than fighting or fleeing.
CaseLocalisation, lateralisation and the brain that rewires itself
Gage's rod suggested functions are localised, and specific areas confirm it: the motor area (movement), the somatosensory area (touch), the visual area (occipital lobe) and the auditory area (temporal lobe). Language is the classic case. Broca's area in the left frontal lobe governs speech production — Broca's patient 'Tan' could understand language but could only say that one syllable. Wernicke's area in the left temporal lobe governs language comprehension — damage there produces fluent but meaningless speech. Because both sit on the left, language is lateralised: the hemispheres are not identical, and some functions are dominated by one side.
Sperry's split-brain research studied patients whose corpus callosum had been cut, so the hemispheres could not communicate, and elegantly demonstrated lateralisation — an object shown only to the right hemisphere could not be named (language is left) but could be selected by the left hand. Yet the brain is not fixed: plasticity is its ability to change and adapt with experience (Maguire found London taxi drivers had enlarged hippocampi from memorising 'the Knowledge'), and functional recovery is how, after trauma, healthy areas take over lost functions through mechanisms such as axonal sprouting and recruitment of the opposite hemisphere. Localisation and plasticity look contradictory but are the two halves of a full answer: the brain has specialised regions and can reorganise them.
A worked 16-mark chunk ('Discuss research into the localisation of function in the brain', 6 AO1 + 10 AO3). AO1, precise and evidenced: 'Localisation theory holds that specific functions have specific brain locations. Language is a strong example: Broca identified an area in the left frontal lobe responsible for speech production, damage to which causes Broca's aphasia — slow, laboured speech — while Wernicke identified a left temporal area for comprehension, damage to which causes fluent but meaningless speech.' Then AO3, each point weighing evidence: 'Support comes from Sperry's split-brain studies, which showed language is processed in the left hemisphere because patients could not verbally name an object presented to the right hemisphere, strong evidence for both localisation and lateralisation. However, the theory can be challenged by plasticity: after damage, other regions can take over lost functions through functional recovery, suggesting function is not rigidly fixed to one location. Lashley's rat research further argued that higher cognitive processes are distributed rather than localised, implying the strict localisation view over-simplifies — the most defensible position is that basic functions are localised while complex ones are distributed.' Each evaluation sentence names its evidence and lands a consequence, which is what lifts an answer into the top band.
DataWays of studying the brain — four windows, four trade-offs
AQA gives you four techniques, and the marks are in their trade-offs — chiefly spatial resolution (how precisely they locate activity) versus temporal resolution (how precisely they time it). fMRI measures blood flow to active brain regions, giving excellent spatial detail and a non-invasive picture of where activity happens — but it has a delay of a few seconds, so its temporal resolution is poor. EEG records the brain's overall electrical activity through scalp electrodes, giving superb temporal resolution (millisecond-by-millisecond) and diagnostic value for conditions like epilepsy — but poor spatial precision, as it cannot pinpoint the source.
ERPs (event-related potentials) refine EEG by averaging many readings to isolate the brain's response to one specific stimulus, combining good temporal resolution with a focus on a single process. Post-mortem examinations dissect the brain after death to link damage to prior behaviour — the historic method behind Broca's and Wernicke's discoveries — but cannot establish causation and cannot be repeated or verified on the living patient. The exam-ready move is to pick the right tool for the question: fMRI to find where, EEG or ERP to find when.
MechanismBiological rhythms — the clocks that run the body
The body runs on cycles, and AQA names three by their length. Circadian rhythms last about 24 hours — the sleep-wake cycle is the key example; Siffre's cave studies, where he lived underground with no time cues, showed his internal clock free-ran to roughly 24–25 hours, proving the rhythm is internally driven but normally adjusted to exactly 24. Infradian rhythms last longer than a day — the menstrual cycle (about 28 days) and seasonal affective disorder (a yearly rhythm) are the examples. Ultradian rhythms are shorter than a day — the roughly 90-minute cycle of sleep stages through the night.
These rhythms are governed by two interacting forces. Endogenous pacemakers are internal body clocks — chiefly the suprachiasmatic nucleus (SCN) in the hypothalamus, which drives the sleep-wake cycle and, via the pineal gland and the hormone melatonin, tells the body when to sleep. Exogenous zeitgebers are external cues that reset those clocks — above all light, but also social cues like mealtimes. The interaction is the whole point: the internal clock keeps roughly 24-hour time on its own, but daily light entrains it to exactly the external day, which is why crossing time zones causes jet lag until the zeitgebers reset the pacemaker.
VocabularyKey terms the mark scheme pays for
TrapsMisconceptions that cost marks
ExamWhat examiners want
Biopsychology is the specification's most factual topic, and short-answer marks (2–6) are pure AO1 that reward precision: name the exact structure, gland, neurotransmitter or brain area rather than gesturing at it. 'A chemical is released' scores little; 'the adrenal medulla releases adrenaline' scores fully. For process questions — synaptic transmission, the fight-or-flight pathway, the divisions of the nervous system — describe the steps in the correct sequence, because examiners credit an accurate ordered chain over a scattered list of true facts.
The 16-mark essays (6 AO1 + 10 AO3) cluster on localisation/lateralisation, plasticity and biological rhythms, and the AO3 depends on named studies and clear counter-arguments: Sperry and Broca for localisation, Maguire for plasticity, Siffre for circadian rhythms. Use them as ammunition, each stated as a Point–Evidence–Explain–Link chain that ends on a consequence for the theory. The strongest evaluation move in this topic is to set two ideas that look opposed against each other — localisation versus plasticity, endogenous pacemakers versus exogenous zeitgebers — and conclude with an interactionist judgement rather than picking one side.
For the 'ways of studying the brain' questions, always answer through the resolution trade-off (spatial versus temporal) and match the technique to the aim — fMRI for where, EEG/ERP for when, post-mortem for structure — as comparison, not description, is where the marks sit. And watch out for the evaluative points AQA specifically rewards, such as the androcentrism criticism of fight or flight (Taylor's 'tend and befriend'), which turns a factual recall question into an analytical one.