How do psychologists study which parts of the brain do which jobs?
Localisation of function and ways of studying the brain: language areas, the role of neuropsychology, Penfield's work, and scanning techniques such as CT, PET and fMRI.
A focused answer to AQA GCSE Psychology 3.7, covering localisation of function (including language areas), the role of neuropsychology and Penfield's work, and the brain scanning techniques used to study the brain such as CT, PET and fMRI.
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What this dot point is asking
AQA wants you to explain localisation of function, describe the role of neuropsychology and Penfield's work, and describe the main ways of studying the brain, including scanning techniques such as CT, PET and fMRI. In Paper 2 you are often asked to compare scans or to explain how a method provides evidence about the brain, so you must know what each technique measures and what its strengths and limitations are.
Localisation of function and language areas
The clearest evidence comes from the language areas. Broca's area, in the left frontal lobe, controls the production of fluent speech; damage to it causes Broca's aphasia, where a person understands speech but produces slow, broken sentences. Wernicke's area, in the left temporal lobe, controls the understanding of language; damage there leaves speech fluent but meaningless. Because two nearby areas can be damaged independently with very different effects, language is a textbook demonstration that functions are localised.
Neuropsychology and Penfield
Scanning techniques
- CT (computerised tomography) scan: uses a series of X-rays to produce a detailed image of the brain's structure, useful for finding physical damage such as tumours or bleeding. It gives a clear structural picture but exposes the person to radiation and shows no activity.
- PET (positron emission tomography) scan: the person is given a small amount of radioactive tracer attached to glucose; active areas use more glucose, so the scan shows which areas are active during a task. It reveals function but uses radioactivity and has lower spatial detail.
- fMRI (functional magnetic resonance imaging): measures changes in blood flow and blood oxygen to show which areas are active in real time, with no radiation. It gives good detail of both structure and activity but is expensive and the person must lie very still.
Try this
Q1. Define localisation of function. [2 marks]
- Cue. The idea that different, specific parts of the brain control different functions.
Q2. Identify the brain area responsible for the production of speech. [1 mark]
- Cue. Broca's area (in the left frontal lobe).
Q3. Explain one strength and one weakness of using fMRI to study the brain. [4 marks]
- Cue. Strength: shows activity in real time without radiation, with good detail. Weakness: expensive and the person must keep very still, so movement spoils the image.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20184 marksExplain one difference between a CT scan and an fMRI scan. (Paper 2, Section C)Show worked answer →
A 4-mark Explain item rewards an identified difference plus developed elaboration of both techniques, not just two separate descriptions.
The key difference is what they show. A CT scan uses X-rays to build a detailed image of the brain's structure, so it is good for finding physical damage such as a tumour or bleed, but it shows a static picture and uses ionising radiation. An fMRI scan measures changes in blood flow and oxygen use to show which areas are active while a person performs a task, so it reveals function in real time without radiation.
Markers reward the explicit contrast (structure versus activity) developed with detail (X-rays versus blood flow, static versus real time). Two unconnected descriptions with no stated difference cap the marks.
AQA 20213 marksDescribe Penfield's contribution to our understanding of the brain. (Paper 2, Section C)Show worked answer →
A 3-mark Describe item needs the method plus what it showed.
Wilder Penfield electrically stimulated small areas of the exposed cortex in conscious patients during surgery for epilepsy, and recorded the sensations or movements they reported. Stimulating one area produced a tingling in a particular body part, another produced a memory or a sound. From mapping these responses he built up a map of which cortical areas control which functions, providing direct evidence for localisation of function.
Markers reward the method (stimulating the cortex in awake patients), the data (patients reported sensations or movements), and the conclusion (a functional map supporting localisation).
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Sources & how we know this
- AQA GCSE Psychology (8182) specification — AQA (2017)