Revise The brain and behaviour for IB Psychology (1.1)

Localisation of function is the idea that specific areas of the brain are responsible for particular tasks. The occipital lobe at the back of the brain processes vision; Broca's area in the left frontal lobe is crucial for producing speech; the motor cortex controls voluntary movement. The concept has deep roots in 19th-century case studies — Phineas Gage, whose personality changed markedly after an iron rod damaged his frontal lobe, suggested that region is involved in personality and self-control.

A study often used to support localisation is HM (Milner & Scoville, 1957). After surgical removal of the hippocampus and surrounding tissue to treat epilepsy, the patient HM could no longer form new long-term memories (anterograde amnesia) yet retained older memories and could learn new motor skills. The specific loss following damage to a specific region is powerful evidence that memory formation is localised to the hippocampus. Note the direction of the argument: damage to an area removes a function, so that area is implicated in that function.

Localisation is only half the story. Neuroplasticity is the brain's ability to reorganise itself by forming, strengthening or removing neural connections throughout life. Two mechanisms matter for the exam. First, experience can STRENGTHEN and grow connections — repeatedly using a pathway (learning an instrument, memorising a city) thickens it. Second, NEURAL PRUNING removes rarely-used synapses so that the surviving, frequently-used pathways become faster and more efficient. Together these processes let the brain adapt to environmental demands and, remarkably, compensate for injury by shifting some functions to undamaged regions.

Behaviour depends on chemistry as well as structure. Neurons communicate at a junction called the synapse. When an electrical impulse reaches the axon terminal, it releases neurotransmitters into the synaptic gap; these cross the gap and bind to receptor sites on the next neuron. An EXCITATORY neurotransmitter (e.g. glutamate) makes the receiving neuron more likely to fire; an INHIBITORY one (e.g. GABA) makes it less likely to fire. A neuron sums the two influences and fires only if excitation outweighs inhibition — this balance underlies everything from muscle movement to mood.

Drugs and toxins act on this system as agonists or antagonists. An AGONIST binds to a receptor and mimics or boosts the neurotransmitter's effect; an ANTAGONIST binds to the receptor and blocks the neurotransmitter, reducing its effect. This overview matters because researchers deliberately use agonists and antagonists to test what a neurotransmitter does: if blocking a neurotransmitter impairs a behaviour, that neurotransmitter is implicated in the behaviour.

Because we cannot ethically damage a living brain to see what a region does, researchers use neuroimaging. Structural MRI produces detailed static images of anatomy — it is what Maguire used to measure hippocampal SIZE. fMRI goes further: it measures ACTIVITY by detecting changes in blood flow and oxygenation while a person performs a task — it is what Antonova used to see reduced hippocampal ACTIVATION under scopolamine. Choosing and evaluating the right technique is a mark-earning skill in itself.

Localisation, plasticity and neurotransmission are not just an opening topic — they underpin the rest of the biological approach: hormones and pheromones, genetics and behaviour, and the ethics of studying the brain all build on the research skills you practised here. In every case the winning habit is the same one this lesson drilled: describe a named study accurately, then explicitly link its findings to the behaviour the question asks about.